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<Network Working Group>                                      A. Y. Chen
Internet Draft                                                 R. R. Ati
Intended status: Experimental               Avinta Communications, Inc.
Expires: June 2020                                        A. Karandikar
                                          India Institute of Technology
                                                             D. R. Crowe
                                              Wireless Telcom Consultant
                                                       December 1, 2019


                        Adaptive IPv4 Address Space
             draft-chen-ati-adaptive-ipv4-address-space-06.txt


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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



   Abstract

   This document describes a solution to the Internet address depletion
   issue through the use of an existing Option mechanism that is part of
   the original IPv4 protocol. This proposal, named EzIP (phonetic for
   Easy IPv4), outlines the IPv4 public address pool expansion and the
   Internet system architecture enhancement considerations. EzIP may
   expand an IPv4 address by a factor of 256M without affecting the
   existing IPv4 based Internet, or the current private networks. It is
   in full conformance with the IPv4 protocol, and supports not only
   both direct and private network connectivity, but also their
   interoperability. EzIP deployments may coexist with existing Internet
   traffic and the IoT (Internet of Things) operations without
   perturbing their setups, while offering end-users the freedom to
   indepdently choose which service. EzIP may be implemented as a
   software or firmware enhancement to Internet edge routers or private
   network routing gateways, wherever needed, or simply installed as an
   inline adjunct hardware module between the two, enabling a seamless
   introduction. The 256M case detailed here establishes a complete
   spherical layer of routers for interfacing between the Internet fabic
   (core plus edge routers) and the end user premises. Incorporating
   caching proxy technology in the gateway, a fairly large geographical
   region may enjoy address expansion based on as little as one ordinary
   IPv4 public address utilizing IP packets with degenerated EzIP
   header. If IPv4 public pool allocations were reorganized, the
   assignable pool could be multiplied 512M fold or even more. EzIP will
   immediately resolve local IPv4 address shortages, while being
   transparent to the rest of the Internet. Under the Dual-Stack
   environment, these proposed interim facilities will relieve the IPv4
   address shortage issue, while affording IPv6 more time to reach
   maturity and to provide the availability levels required for
   delivering a long-term general service.

   Table of Contents


   1. Introduction...................................................4
      1.1. Contents of this Draft....................................5
   2. EzIP Overview..................................................6
      2.1. EzIP Numbering Plan.......................................6
      2.2. Analogy with NAT..........................................7
      2.3. EzIP System Architecture..................................9


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      2.4. IP Header with Option Word...............................11
      2.5. Examples of Option Mechanism.............................12
      2.6. EzIP Header..............................................13
      2.7. EzIP Operation...........................................14
   3. EzIP Deployment Strategy......................................14
   4. Updating Servers to Support EzIP..............................17
   5. EzIP Enhancement and Application..............................18
   6. Security Considerations.......................................22
   7. IANA Considerations...........................................22
   8. Conclusions...................................................22
   9. References....................................................23
      9.1. Normative References.....................................23
      9.2. Informative References...................................23
   10. Acknowledgments..............................................24
   Appendix A  EzIP Operation.......................................25
      A.1. Connection between EzIP-unaware IoTs.....................25
         A.1.1. T1a Initiates a Session Request towards T4a.........25
         A.1.2. RG1 Forwards the Packet to SPR1.....................26
         A.1.3. SPR1 Sends the Packet to SPR4 through the Internet..27
         A.1.4. SPR4 Sends the Packet to T4a........................28
         A.1.5. T4a Replies to SPR4.................................29
         A.1.6. SPR4 Sends the Packet to SPR1 through the Internet..30
         A.1.7. SPR1 Sends the Packet to RG1........................31
         A.1.8. RG1 Forwards the Packet to T1a......................32
         A.1.9. T1a Sends a Follow-up Packet to RG1.................32
      A.2. Connection Between EzIP-capable IoTs.....................33
         A.2.1. T1z Initiates a Session Request towards T4z.........33
         A.2.2. RG1 Forwards the Packet to SPR1.....................34
         A.2.3. SPR1 Sends the Packet to SPR4 through the Internet..35
         A.2.4. SPR4 Sends the Packet to T4z........................36
         A.2.5. T4z Replies to SPR4.................................37
         A.2.6. SPR4 Sends the Packet to SPR1 through the Internet..38
         A.2.7. SPR1 Sends the Packet to RG1........................39
         A.2.8. RG1 Forwards the Packet to T1z......................40
         A.2.9. T1z Sends a Follow-up Packet to RG1.................41
      A.3. Connection Between EzIP-unaware and EzIP-capable IoTs....42
         A.3.1. T1a Initiates a Request to T4z......................42
         A.3.2. T1z Initiates a Request to T4a......................42
   Appendix B  Internet Transition Considerations...................43
      B.1. EzIP Implementation......................................43
      B.2. SPR Operation Logic......................................44
      B.3. RG Enhancement...........................................45
   Appendix C  EzIP Realizability...................................47
      C.1. 240/4 Netblock Capable IoTs..............................47
      C.2. 240/4 Netblock Capable Routers...........................47
      C.3. Enhancing an RG..........................................48
      C.4. SPR Reference Design.....................................49


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      C.5. RAN Deployment Model.....................................49
   Appendix D  Enhancement of a Commercial RG.......................51
      D.1. Candidate Code for Modification..........................51
      D.2. Proposed Modification....................................51
      D.3. Performance Verification.................................52


   1. Introduction

   For various reasons, there is a large demand for IP addresses. It
   would be useful to have a unique address for more Internet devices,
   such that, if desired, any device may call upon any other directly.
   The Internet of Things (IoT) would also be able to make use of more
   routable addresses if they were available. Currently, these are not
   possible with the existing IPv4 configuration.

   By Year 2020, the world population and number of IoTs are expected to
   reach 7.6B (Billion) and 50B respectively, according to a 2011 Cisco
   online white paper [3].

   In addition, IP addresses are needed while client devices, such as
   mobile phones, are attached to the internet, which is an increasing
   demand due to a rapidly increasing number of devices.

   The IPv4 dot-decimal address format, consisting of four octets each
   made of 8 binary bits, provides just over 4 billion unique addresses
   (256 x 256 x 256 x 256 equals 4,294,967,296 - decimal exact). Using
   the binary / shorthand notation of 64K representing 256 x 256
   (decimal 65,536), the full IPv4 address pool of 64K x 64K may be
   expressed as 4,096M (Million), or 4.096B (or, further rounded down to
   4B for quick estimate calculations). Clearly, the predicted demand is
   more than 12 times over the inherent capacity available from the
   supply.

   IPv6, with its 128-bit hexadecimal address format, is four times as
   long as the IPv4, has 256BBBB (4B x 4B x 4B x 4B) unique addresses.
   It offers a promising solution to the address shortage. However, its
   global adoption appears to be facing significant challenges [4], [5].

   Interim relief to the IPv4 address shortage has been provided by
   Network Address and Port Translation (NAPT - commonly known simply as
   NAT) on private networks together with Carrier Grade NAT (CG-NAT or
   abbreviated further to CGN) [RFC6598] [6] over the public Internet.
   However, NAT modules slow down routers due to the state-table look-up
   process. As well, they only allow an Internet session be initiated by
   their own clients, impeding the end-to-end setup requests initiated
   from remote devices that a fully functional communication system


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   should be capable of. Being dynamic, the state-table used by CG-NAT
   increases CyberSecurity vulnerability. Since port numbers are used to
   effectively increase the size of the address pool, they introduce
   complex and suboptimal port management requirements. On the other
   hand, private network NAT as part of a Routing / Residential Gateway
   (RG) does provide a rudimentary defense against intrusion. To
   minimize confusion, we will explicitly label this NAT as RG-NAT in
   this document to distinguish from CG-NAT.

   If IPv4 capacity could be expanded without the size and efficiency
   limitations of CG-NAT, the urgency will be relaxed long enough for
   the IPv6 to mature on its own pace.

   There have been several proposals to increase the effective Internet
   public address pool in the past. They all introduced new techniques
   or protocols that ran into certain handicaps or compatibility issues,
   preventing a smooth transition.

   EzIP utilizes a long-reserved network address block (netblock) 240/4
   [7] that all of the existing Internet Core (/ backbone) Router (CR),
   Edge Router (ER) and private network Routing (/ Residential) Gateway
   (RG) as well as terminal hosts such as IoTs are not allowed to
   utilize. This is combined with the Option mechanism defined in
   [RFC791] [1] for transporting such information as the IP header
   payload that is transparent to all of these routers, except a newly
   defined category named Semi-Public Router (SPR). By inserting an SPR
   between an ER and a private premises that it serves, each publicly
   assignable address can be expanded 256M fold.

   EzIP introduces minimal perturbation by being compatible to the
   current Internet system architecture. Its deployment will start with
   an SPR providing public NAT functions to unload the burden from the
   current CG-NAT. With basic routing as an integral part of the SPR,
   directly connected individual IoTs and private networks, will be
   encouraged to migrate toward the full EzIP service which provides
   end-to-end connectivity between and among them.

        1.1. Contents of this Draft

   This draft outlines the EzIP numbering plan. An enhanced IP header,
   called EzIP header, is introduced to carry the EzIP address as
   payload using the Option word. How the Internet architecture will
   change as the result of being extended by the EzIP scheme is
   explained. How the EzIP header flows through various routers, and
   Internet update considerations are described, with details presented
   in Appendices A and B, respectively. Utilizing the EzIP approach,
   several ways to expand the publicly assignable IPv4 address pool, as


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   well as enhance Internet operations are then discussed. Appendix C
   outlines the experimental effort to demonstrate the feasibility of
   EzIP by configuring a regional area network model based on current
   networking equipment upon finite enhancements. Appendix D is a Work-
   In-Progress report about the enhancement of a specific commercial RG.



   2. EzIP Overview

       2.1. EzIP Numbering Plan

   EzIP uses the reserved private network address pools in very much the
   same way that Private Automatic Branch eXchange (PABX) switching
   machines utilize locally assigned "extension numbers" to expand the
   Public Switched Telephone Network (PSTN) capacity, by replicating a
   public telephone line to multitudes of reusable private telephone
   numbers, each to identify a local instrument.

   At the first sight, this correlation may seem odd, because the PABX
   extension numbers belong to a reusable private set separate from that
   of the public telephone numbers and both are independently
   expandable, while private network IP address is a specific subset
   reserved from the overall IPv4 pool that is otherwise all public and
   finite. However, the fact that neither of the latter two is allowed
   to operate in the other's domain the same as in the telephony
   practice suggests that the proposed EzIP numbering plan indeed may
   mirror the PABX. For example, extension 123 or 1234 may exist in
   thousands of different PABX switches without ambiguity. Similarly,
   the IPv4 private network address (10/8, 172.16/12 and 192.168/16) may
   also be re-used in many networks without ambiguity.

   The key EzIP concept is the partitioning of a finite public address
   pool to put aside a block of special (called "Semi-Public" in the
   presentation below) addresses that extends each remaining public
   address to multitudes of sub-addresses, resulting in an effectively
   much larger assignable public address resource.

   In fact, the initial EzIP analysis identified the untold two-stage
   subnetting process of 192.168/16 that has been practiced routinely
   for a long time. End-users are commonly accustomed to an RG choosing
   one out of 256 values from the fourth octet of the 192.168.K/24
   address block for identifying an IoT on a private premises. They
   mostly are, however, unaware of the preceeding stage of selecting the
   value "K" from the third octet of the 192.168/16 block, as the
   factory default RG identification assigned by a manufacturer, is
   implicitly capable of expanding it by 256 fold for supporting a


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   corresponding number of private premises. A key EzIP concept is to
   use the elusive IPv4 240/4 netblock (240/8 - 255/8), that has been
   "RESERVED" for "Future use" since 1981-09, as the result of the
   historical address assignment evolution. It was proposed to be
   redesignated to "Private Use" over a decade ago [2]. However, as
   pointed out by its own authors in Section 2, Caveats of Use, "Many
   implementations of the TCP/IP protocol stack have the 240.0.0.0/4
   address block marked as experimental, and prevent the host from
   forwarding IP packets with addresses drawn from this address block."
   That proposal did not get advanced. Therefore, to this date, the
   240/4 netblock remains reserved for future use.

   Substituting the function of the third octet of 192.168.K/24 with
   addresses from the 240/4 netblock in the first stage RG and
   redefining it as a new category of router, called SPR, the EzIP
   scheme circumvents the earlier hurdles to achieve the address
   multiplication factor of 256M without involving any existing router.
   This is because the 240/4 addresses are only used within the SPR and
   within the Option word header extension. They are not recognized as
   IPv4 addresses anywhere within the current Internet. These addresses
   are equivalent to PABX extension numbers that IPv4 Option word
   mechanism can carry them through the network.

   Since the 240/4 netblock cannot be used by existing routers, the size
   of the maximum assignable IPv4 public pool has actually been only
   3.84B (4.096B - 256M). So, the overall assignable pool resulted from
   the EzIP approach is about 983MB (3.84B x 256M), which is over 19M
   times of the expected Year 2020 IoTs. This size certainly has the
   potential to support the short- to mid-term public IP address needs.



       2.2. Analogy with NAT

   NAT generally works by temporarily assigning a port number to
   outgoing communications from a local / private address, while
   converting it into a public IPv4 address for external communications.
   When responses to messages are received, the public IPv4 address plus
   port number is converted back into the local / private IPv4 address.

   EzIP possesses similarities to NAT, but also has some important
   differences.

   There are a number of limitations of NAT that are not present with
   EzIP. (1) There are only 65,536 port numbers but 256M 240/4 EzIP
   addresses; (2) Due to the limited number of ports, assignments are
   only temporary and will be reclaimed after a period of inactivity,


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   but there are so many EzIP addresses that assignments will be made
   permanent; (3) Port numbers are used for other purposes than NAT,
   further reducing the pool, but EzIP uses 240/4 addresses solely for
   one purpose; (4) Due to the limited time during which a port number
   is assigned, the NAT port numbers cannot be used for incoming
   communications, but the EzIP address assignments will be long term
   and can be used for direct communications between EzIP-aware devices.
   (5) Intriguingly, while RG-NAT provides rudimental defense agaist
   intrusion, the dynamic nature of CG-NAT opens up the Internet
   vulnerability to cyber attacks, due to its inherent lack of forensic
   traceability. EzIP will eventually replace CG-NAT for a transparent
   path.





































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       2.3. EzIP System Architecture



                                       +------+
                        Web Server     | WS0z |
                                       +--+---+
                                          |69.41.190.145
                                          |
                                          |  +-----+
                                          +--+ ER0 |
                                             +--+--+
                                                |
                                         +------+-------+
                                 +-------+ Core Routers +--------+
                                 |       | (CR/Internet)|        |
                              +--+--+    +--------------+     +--+--+
                        +-----+ ER1 |                   +-----+ ER4 |
                        |     +-----+                   |     +-----+
                        |                               |
                        |69.41.190.110                  |69.41.190.148
          240.0.0.0  +--+--+                         +--+--+
         +-----------+     +-------+       +---------+     +------+
         |     +-----+ SPR1|       |       |   +-----+ SPR4+--+   |
         |     |     +-----+       |       |...|     +-----+  |...|
         | 240.0.0.1   ... 255.255.255.255 |   |    +---------+   |
         +-----+                           |   |    |             |
        Public |                     240.0.0.0 |    |    255.255.255.255
   Demarc. ----+-------------------------------+----+-------------------
       Private |Premises 1          +----------+    |
            +--+--+                 |   Premises 4  |
        +---+ RG1 +--+              |               |
        |   +-----+  |              |               |
        |            |              |               |
        |192.168.1.3 |192.168.1.9   |240.0.0.10     |246.1.6.40
     +--+--+      +--+--+        +--+--+         +--+--+
     | T1a | .... | T1z |        | T4a | ....... | T4z |
     +-----+      +-----+        +-----+         +-----+


                    Figure 1  EzIP System Architecture

   The new category of router, SPR is to be positoned inline between an
   ER and the customer premises that it serves. After the original path
   is re-established, the remaining addresses in the 240/4 netblock will


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   be used by the SPR to serve additional premises. Figure 1 shows a
   general view of the enhanced Internet system architecture with two
   SPRs, SPR1 and SPR4, deployed. Note that the "69.41.190.x" are static
   addresses. In particular, the "69.41.190.145" is the permanent public
   Internet address assigned to Avinta.com.

   2.3.1.   Referring to the lefthand portion labeled "Premises 1" of
   Figure 1, instead of assigning each premises a public IPv4 address as
   in the current practice, an SPR like SPR1, is inserted between an ER
   (ER1) and its connections to private network Routing Gateways like
   RG1, for utilizing 240.0.0.0 through 255.255.255.255 of the 240/4
   netblock to identify respective premises. The RG1, serving either a
   business LAN (Local Area Network) or a residential HAN (Home Area
   Network), uses addresses from one of the three private network
   [RFC1918] [8] blocks, 10/8, 172.16/12 and 192.168/16, such as
   192.168.1.3 and 192.168.1.9 to identify the IoTs, T1a and T1z,
   respectively.

   2.3.2.   Part of the righthand portion of Figure 1 is labeled
   "Premises 4". Here SPR4 directly assigns addresses 240.0.0.10 and
   246.1.6.40 from the 240/4 netblock to T4a and T4z, respectively.
   Consequently, these IoTs are accessible through SPR4 from any other
   IoT in the Internet.

   2.3.3.   Since the existing physical connections to subscriber's
   premises terminate at the ER, it would be natural to have SPRs
   collocated with their ER for streamlining the interconnections. It
   follows that the simple routing function provided by the new SPR
   modules may be absorbed into the ER through a straightforward
   operational firmware enhancement. Consequently, the public / private
   demarcation line (Demarc.) will remain at the RG where currently all
   utility services enter a subscriber's premises.

   2.3.4.   To fully tag each of these devices, we may use a
   concatenated three-part address notation: "Public - Semi-Public: TCP
   Port". The following is how each of the IoTs in Figure 1 may be
   uniquely identified in the Internet.

            RG1: 69.41.190.110-240.0.0.0

            T1a: 69.41.190.110-240.0.0.0:3

            T1z: 69.41.190.110-240.0.0.0:9

            T4a: 69.41.190.148-240.0.0.10

            T4z: 69.41.190.148-246.1.6.40


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   Note that to simplify the presentation, it is assumed at this
   juncture that the conventional TCP (Transmission Control Protocol)
   [RFC793] [9] Port Number, normally assigned to T1a and T1z by RG1's
   RG-NAT module upon initiating a session, equals to the fourth octet
   of that IoT's private IP address that is assigned by the RG1's DHCP
   (Dynamic Host Configuration Protocol) [RFC2123] [10] subsystem as
   ":3" and ":9", respectively. Such numbers are unique within each
   respective /24 private network such as the 192.168.1/24 here. They
   are adequate for the discussion purpose in this document. However,
   considering security, as well as allowing each IoT to have multiple
   simultaneous sessions, etc., this direct and singular correlation
   shall be avoided in actual practice by following the RG-NAT operation
   conventions as depicted by the examples in Appendix A.

  Figure 2 groups IoTs, routers and servers into two separate columns,
  EzIP-unaware or EzIP-capable, to facilitate discussions that are to
  follow.

     +--------------------------+-----------------+----------------+
     |                          |   EzIP-unaware  |  EzIP-capable  |
     +--------------------------+-----------------+----------------+
     | Internet Core Router (CR)|       CR        |  ------------  |
     +--------------------------+-----------------+----------------+
     | Internet Edge Router (ER)|  ER0, ER1, ER4  |  ------------  |
     +--------------------------+-----------------+----------------+
     | Internet of Things (IoT) |    T1a, T4a     |    T1z, T4z    |
     +--------------------------+-----------------+----------------+
     | Routing Gateway (RG)     |       RG1       |  ------------  |
     +--------------------------+-----------------+----------------+
     | Semi-Public Router (SPR) |  -------------  |   SPR1, SPR4   |
     +--------------------------+-----------------+----------------+
     | Web Server (WS)          |  -------------  |      WS0z      |
     +--------------------------+-----------------+----------------+

                     Figure 2  EzIP System Components

       2.4. IP Header with Option Word

   To transport the EzIP Extension Addresses through existing devices
   without being recognized as such and consequently acted upon, the IP
   Header Option mechanism defined by Figure 9 in Appendix A of [RFC791]
   is utilized to carry it as the payload. One specific aspect of its
   format deserves some attention. The meanings of the leading eight
   bits of each Option word, called "Opt. Code" or "Option-type octet",
   are summarized on Page 15 of [RFC791]. They are somewhat confusing
   because the multiple names used in the literature, and how the octet
   is parsed into functional bit groups. For example, a two digit


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   hexadecimal number, "0x9A", is conventionaly written in the binary
   bit string form as "1001 1010". As Opt. Code, however, the eight bits
   here are parsed into three groups of 1, 2 and 5 bits as "1 00 11010"
   with meanings described in Figure 3.

      +--------------------------------------------------------------+
      |           Meaning of EzIP ID = 0x9A (Example)                |
      +--------------+------------------+----------------------------+
      |   Copy Bit   |      Class       |   Option Value / Number    |
      +--------------+------------------+----------------------------+
      |    1 (Set)   |   00 (Control)   |     11010 (26 - base 10)   |
      +--------------+------------------+----------------------------+


                        Figure 3  Option Type Octet

   A value of "1" for the first bit instructs all routers that this
   Option word is to be copied upon packet fragmentation. This preserves
   the Option word through such a process, if it is performed.

   The value of "00" for the next two bits indicates that this Option
   word is for "Control" purpose.

   The decimal "Option Value" of the last five bits, equaling to "26" is
   defined as the "Option Number" that is listed in the  "Number" column
   of the Internet Protocol Version 4 (IPv4) Parameters list [11]. As
   can be seen there, "26" has not been assigned. Thus, it is
   temporarily used in this document to facilitate the EzIP
   presentation. The next unassigned Option Code, "0x9B" or Number "27"
   will also be tentatively utilized in this document.

       2.5. Examples of Option Mechanism

   The Option mechanism has been used for various cases. Since they were
   mostly for utility or experimental purposes, however, their formats
   may be remote from the incident topic. There were two cases
   specifically dealt with the address pool issues. They are referenced
   here to assist the appreciation of the Option mechanism.

      A. EIP (Extended Internet Protocol) - Figure 1 of [RFC1385] [12]
   (Assigned but now deprecated Option Number = 17) by Z. Wang: This
   approach proposed to add a new network layer on top of the existing
   Internet for increasing the addressable space. Although equipment
   near the end-user would stay unchanged, those among the CRs
   apparently had to go through rather extensive upgrading procedures,
   perhaps due to the flexible length of the extended address (could be
   much longer than that of the IPv6).


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      B. EnIP (Enhanced IPv4) - Figure 1 of Internet Draft [13]
   (temporarily utilizing Option Number = 26) by W. Chimiak: This work
   made use of the three existing private network blocks to extend the
   public pool by trading the private network operation for end-to-end
   connectivity. The fully deployed EnIP will eliminate the current
   private networks which may be against the preference of end-users who
   have found the private network configuration quite desirable. For
   example, the RG-NAT serves as a rudimentary deterrent against
   intrusion. In addition, the coexistence of private RG-NAT and public
   EnIP router functions in the same EnIP devices (N1 & N2), could lead
   to certain logistic inconsistency concerns.

       2.6. EzIP Header

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|      Total Length (32)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |                      Source Host Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |                    Destination Host Number                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |     No.-1     |     No.-2     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |     No.-3     |     No.-4     |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |     No.-1     |     No.-2     |     No.-3     |     No.-4     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 4  Full EzIP Header

   The proposed EzIP header format shown in Figure 4 can transport the
   full 4 octet (32 bit) extension addresses of both ends of an Internet
   link. The extension address in the 240/4 netblock utilized in the
   EzIP scheme described herein has 28 significant bits. It is possible
   for EzIP to use addresses having other lengths of significant bits


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   for different multiplication factors. To prepare for such variations,
   two separate EzIP ID codes, "0x9A" and "0x9B" are proposed to
   distinguish between Source and Destination Option words,
   respectively, as basic examples.



       2.7. EzIP Operation

   To convey the general scheme, Appendix A presents examples of IP
   header transitions through routers, between IoTs with or without EzIP
   capability.

   To introduce the EzIP approach into an environment where EzIP-unaware
   IoTs like T1a and T4a will be numerous for a long time to come, an
   SPR must be able to follow certain decision branches to determine how
   to provide the appropriate routing service for a smooth transition to
   the long term operation. Appendix B outlines such logic and related
   considerations.



   3. EzIP Deployment Strategy

   Although the eventual goal of the SPR is to support both web server
   access by IoTs from behind private networks and direct end-to-end
   connectivity between IoTs, the former should be dealt with first to
   immediately mitigate the address shortage induced daily issues. In
   the process, the latter would be built up naturally.

   A. Architecturally

   Since the design philosophy of the SPR is an inline module between an
   ER and the private premises (RG or directly connected IoTs) that it
   serves, SPR introduction process can be flexible.

      A.1.  An SPR may be deployed as an inline module right after an ER
   to begin providing the CG-NAT equivalent function. This could be done
   immediately without affecting any of the existing Internet
   components, CR, ER and RG. EzIP-capable IoTs will then take advantage
   of the faster bi-directional routing service through the SPRs by
   initiating communication sessions utilizing EzIP headers to contact
   other EzIP-capable IoTs.

      A.2.  Alternatively, an SPR may be deployed as an adjunct module
   just before an existing RG or a directly connected IoT to realize the
   same EzIP functions on the private premises, even if the serving


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   Internet Access Provider (IAP) has not enhanced its ERs with the EzIP
   capability.

      This approach will empower individual communities to enjoy the new
   EzIP capability on their own by upgrading all Internet subscribers
   within a good sized region to have publicly accessible EzIP addresses
   for intra-community peer-to-peer communication, starting from just
   using one existing public IPv4 address to identify the entire region
   through a gateway to the rest of the world. See sub-section C. below
   for more specific considerations.

   B. Functionally

      B.1.  First, an IAP should install SPRs in front of business web
   servers so that new routing branches may be added to support the
   additional web servers for expanding business activities.
   Alternatively, this may be achieved if businesses on their own deploy
   new web servers with the SPR capability built-in.

      B.2.  On the subscriber side, SPRs should be deployed to
   disseminate static addresses to the public, and to facilitate the
   access to new web servers.

   C. Regional Area Network

      C.1.  Since the size of the 240/4 netblock is significant, a
   region mentioned in sub-section A.2. above could actually be fairly
   large. Based on the assumption that each person, on the average, may
   have 6.6 IoTs by Year 2020 Error! Reference source not found., a
   240/4 netblock is capable of serving nearly 39M (256M / 6.6)
   individual devices, even before using any private network. This
   exceeds the population of the largest city on earth (38M - Tokyo
   Metro.) and 75% of the countries around the world (most of the 233
   countries other than the top 35). Therefore, any finite sized region
   can immediately begin to enjoy EzIP addressing by deploying a
   Regional Area Network (RAN) utilizing SPRs operating with one 240/4
   netblock of addresses from one IPv4 public address. With the gateway
   for a region configured in such a way that the entire region appears
   to be one ordinary IPv4 IoT to the rest of the Internet, a self-
   contained RAN may be deployed anywhere there is the need or desire,
   with no perturbation to the current Internet operations whatsoever.

      C.2. This gateway may be constructed with a matured networking
   technology called Caching Proxy [14], popularized by data-intensive
   web services such as Google, Amazon, Yahoo, etc. Developed for
   speeding up response to repetitive queries on the same topic, while
   consolidating Internet traffic for data exchanges with the central


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   data bank, caching proxies are placed at strategic locations close to
   potential inquirers, essentially cloning the central data bank into
   distributed copies (not necessarily a full set, but containing all
   relevant subsets pertaining to the local community). This
   architecture meshs with the EzIP-based RAN very well, because the
   address translation between the IPv4 in the Internet and the EzIP in
   the RAN can be accomplished transparently through the two ports of a
   caching proxy (For such matter, even could be between the IPv6 and
   the EzIP if desired!). Consequently, existing Internet routers, such
   as CR and ER may not see any IP packet with EzIP header at all,
   during the initial phase of the RAN deployment which will primarily
   consist of basic intra-regional messaging and web service access in a
   primarily local operation mode.

      C.3.  This configuration actually mimicks the PABX environment
   almost exactly. Since the entire region is only accessible through
   the gateway that performs the address translation, degenerated EzIP
   header (conventional IP header with words 4 and 5 using 240/4
   netblock addresses) will be suffice for the intra RAN traffic. This
   mirrors the dialing procedure of using only extension numbers among
   stations served by the same PABX, circumventing the unnecessary and
   wasteful overhead of including the dialing of the common public
   telephone number prefix whose only purpose is to identify the PABX to
   the PSTN which is not involved in such intra- communications.

      C.4.  The full EzIP header format will only be used when an EzIP-
   capable IoT intends to directly interact with an EzIP-capable IoT in
   another RAN. The last part is equivalent to the DID (Direct Inward
   Dialing) conventions when a call is made through the PSTN to a
   station in another PABX.

      C.5.  The RAN would streamline the CIR (Country-based Internet
   Registry) model proposed by ITU-T [18] as well. Instead of allocating
   a block of public IPv6 addresses to an ITU-T authorized entity
   (essentially the sixth RIR - Regional Internet Registry) to
   administrate on behalf of individual countries, the EzIP RAN
   configuration enables each member state to start her own CIR with up
   to 256M IoTs, based on just one of the IPv4 public address already
   allocated to that country from the responsible RIR. Consequently,
   each CIR is coordinated by its parent RIR, yet its operation can
   conform to local preferences. This configuration will establish a
   second Internet service parallel to the existing one for
   demonstrating their respective merits independently, offering
   subscribers true options to choose from.

   D. Permanently



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   In the long run, it would be best if SPRs are integrated into their
   host ER by upgrading the latter's firmware to minimize the hardware
   and to streamline the equipment interconnections.

   Appendix B details the considerations in implementing these outlines.



   4. Updating Servers to Support EzIP

   Although the IP header Option mechanism utilized by EzIP was defined
   a long time ago as part of the original IPv4 protocol [RFC 791] [1],
   it has not been used much in daily traffic. Compatibility with
   current Internet facilities and conventions may need be reviewed.
   Since the EzIP data is transported as part of the IP header payload,
   it is not expected to affect higher layer protocols. However, certain
   facilities may have been optimized without considering the Option
   mechanism. They need be adjusted to provide the same performance to
   EzIP packets. There are also utility type of servers that need be
   updated to support the longer EzIP address. For example;

   A. Fast Path

   Internet Core Routers (CRs) are currently optimized to only provide
   the "fast-path" (through hardware line card) routing service to
   packets without Option word in the IP header [15]. This puts EzIP
   packets at a disadvantage, because EzIP packets will have to go
   through the "slow path" (processed by CPU's software before giving to
   the correct hardware line card to forward), resulting in a slower
   throughput. Since the immediate goal of the EzIP is to ease the
   address pool exhaustion affecting web server access, subscribers not
   demanding high throughput performance may be migrated to the EzIP
   supported facility first. This gives CRs the time to update so that
   EzIP packets with authorized Option numbers will eventually be
   recognized for receiving the "fast-path" service. On the other hand,
   an alternative logic may be applied for the CR. That is, it should by
   default ignore any Option word in an IP header so that all IP packets
   will be processed through the "fast-path", unless a recognizable
   Option word requiring action is detected. This approach would
   mitigate the security issues caused by the "source routing" attack,
   as well.

   B. Connectivity Verification

   One frequently used probing utility for verifying baseline
   connectivity, commonly referred to as the "ping" function in PC
   terminology, needs be able to transport the full EzIP address that is


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   64 bits long instead of the current 32 bit IPv4 address. There is an
   example of an upgraded TCP echo server in [RFC862] [16].

   C. Domain Name Server (DNS)

   Similarly, the DNS needs to expand its data format to transport the
   longer IP address created by the EzIP. This already can be done under
   IPv6. Utilizing the experimental IPv6 prefix 2001:0101 defined by
   [RFC2928] [17], EzIP addresses may be transported as standardized
   AAAA records.

   These topics are discussed in more detail under an IETF Draft RFC,
   Enhanced IPv4 - V.03 [13].



   5. EzIP Enhancement and Application

   To avoid disturbing any assigned addresses, deployed equipment and
   current operation, etc., the EzIP scheme is derived under the
   constraint of utilizing only the reserved 240/4 address block. If
   such restriction were removed by allowing the entire IPv4 address
   pool be freely re-allocatable, the assignable public address pool
   could be expanded significantly more, as outlined below.

   A. If the 240/4 netblock were doubled to 224/3, each existing IPv4
   public address would be expanded by 512M fold. Since this block of
   512M addresses have to be first reserved from the basic public pool,
   the resultant total addresses will be (4.096B - 512M) x 512M, or
   1,835MB. This is over 36M times of the predicted number of IoTs (50B)
   by Year 2020. This calculation leads to additional possibilities.

   B. The EzIP header in Figure 4, capable of transporting the full 32
   bit IPv4 address, allows the extension number to be as long as
   practical. That is, we can go to the extreme of reserving only one
   bit for the network number, and using all the rest of bits for the
   extension address. With this criterion, the basic IPv4 pool may be
   divided into two halves, reserving one half of it (about 2B
   addresses) as a semi-public network with the network number prefix
   equal to "1". Each of the remaining 2B public addresses (with prefix
   equal to "0") of the basic IPv4 pool may then be extended 2B fold
   through the EzIP process, resulting in a 4BB address pool. This is
   roughly 80M times of the Year 2020 IoT needs.

   C. If the EzIP technique were applied through several layers of SPRs
   in succession, the address expansion could be even more. For example,
   let's divide the IPv4 pool equally into four blocks, each with about


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   1B addresses. Apply the first 1B address block to the public routers.
   Set up three layers of SPRs, each makes use of one of the remaining
   three 1B addresses. The resultant assignable pool will have 1BBBB
   addresses. Under this configuration, the full length of an IoT's
   identification code will be the concatenation of four segments of 32
   bit IPv4 address, totalling 128 bits, the same as that of the IPv6.
   The first two bits of each segment, however, being used to
   distinguish from the other three address blocks, are not significant
   bits. This 8-bits difference makes the IPv6 pool 256 times larger.
   This ratio is immaterial, because even the 1BBBB address pool is
   alreaby 20MBB times of the foreseeable need. It is the hierarchical
   addressing characteristics, made possible by the EzIP scheme, that
   will enhance the Internet, such as truncating out the common address
   prefix for communicating within a local community, and associating an
   address with the geographical position, thus mitigating the
   GeoLocation related issues.

   D. Along this line of reasoning, we could combine two 1B address
   blocks togther to be the basic public address. The overall assignable
   pool becomes 2BBB which is still 40MB times of the expected IoT
   need(50B). With this pool, we can divide the entire globe into 2B
   regions, each served by one public router. Each region can then be
   divided into 1B sections, identified by the first group of SPRs.
   Next, each section will have the second group of SPRs to manage upto
   1B RGs and IoTs. Since the basic 2B public addresses are already more
   than half of the current total assignable IPv4 public addresses
   (3.84B), their potential GeoLocation resolution capabilities are
   comparable. With additional two layers of SPR routing, 1B for each,
   the address grid granuality will be so refined that locating the
   source of an IP packet becomes a finite task, leaving perpetrators
   little room to hide.

   E. The following outlines a possible procedure for optimizing the use
   of the EzIP address resource by transforming the current Internet to
   be a GeoLocation-capable address system while maintaining the
   existing IPv4 addressing and operation conventions:

      a. Quantitative Reference: IETF [RFC6598] [6] reserved the
   100.64/10 block with 4M addresses for supporting IAP's CG-NAT
   service. Applying all of these to the entire IPv4 pool of 4B
   addresses, the maximum effective CG-NAT supported IPv4 address pool
   could be 16MB. This is 0.32M times of the expected number (50B) of
   IoTs by Year 2020.

      b. Employing the 240/4 netblock with 256M addresses in the EzIP
   extension scheme, a /6 block with 64M addresses from the IPv4 basic



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   public pool is sufficient to replicate the above 16MB capacity. This
   frees up the majority of the IPv4 public pool.

      c. Since this will be a temporary holding pool to release the
   current addresses for new assignments, it should occupy as few public
   addresses as possible to leave the maximum number of addresses for
   facilitating the long term planning. To just support the expected 50B
   IoTs need, only 200 IPv4 public addresses are required (200 x 256M =
   50B). Thus, a /24 block with 256 addresses is more than enough to
   accommodate this entire migration process. This frees up even more
   IPv4 public addresses.

      d. Although a single /24 public address block is sufficient for
   migrating all currently perceived IPv4 address needs into one compact
   temporary EzIP pool, world-wide coordination of new address
   assignments and routing table updates will be required. It will be
   more expeditious to carry out this preparatory phase on an individual
   country or geographical region basis utilizing public IPv4 addresses
   already assigned to that area and actively served by existing CR
   routing tables. Since 200 public addresses are enough to port the
   entire IoT addresses, most of the 233 countries other than the top 35
   (about 75%) countries should be able to port all of their respective
   predicted IoTs to be under one 240/4 netblock, each represented by
   one gateway to the Internet. If this is managed according to
   geographical disciplines, each participating region will begin to
   enjoy the benefits of the EzIP approach, such as plentiful assignable
   public addresses, robust security due to inherent GeoLocation ability
   to spot hackers from within, so that efforts may be focused only on
   screening suspicious packets originated from outside.

      e. As IoTs are getting migrated to the temporary pool, the IPv4
   addresses they originally occupy shall be released to re-populate the
   public address pool for establishing full scale EzIP operation.

      f. Upon the completion of the EzIP based world-wide public address
   allocation map, each country can simply give up the few temporary
   public addresses in exchange for the permanent assignments. Since the
   latter is likely more than the former, addresses in one 240/4
   netblock will be served by two (or more) 240/4 netblocks. Then, each
   of such 240/4 netblock will have more than half of its capacity
   available to serve the growth of additional IoTs.

      g. This last step is very much the same as the traditional PSTN
   "Area Code Split" practice, whereby telephone numbers of a service
   area are split into two (or more) blocks, upon introducing one (or
   more) new area code(s) into the area. All subscribers will continue
   to use their original local telephone numbers for calling among


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   neighbors daily, except some may be assigned with a new area code
   prefix. Upon the split, each area code will have more than half of
   its assignable telephone numbers availabe to support the future
   subscriber growth within its service area. Mimicking the PSTN, the
   EzIP based Internet will have similar GeoLocation capability as the
   former's caller identification based services, such as the 911
   emergency caller location system in US, mitigating the root cause to
   the cybersecurity vulnerability.

   F. With the IPv4 address shortage issue resolved, potential system
   configurations utilizing the EzIP enhanced address pool may be
   explored.

      a. Although the entire predicted number (50B) of IoTs by Year 2020
   may be served by just one /24 IPv4 public address block utilizing the
   EzIP scheme with a 240/4 netblock, let's replace it with a /8 block
   (16M addresses), resulting in about 4MB (16M x 256M) assignable
   addresses. This is 80K times of the expected 50B IoTs. Or, each and
   every person (of predicted 2020 population) would have to own over
   500K IoTs to use up this address pool. It is apparent that the spares
   in this allocation should be sufficient to support the growth of the
   IoTs for some years to come.

      b. Next, the IPv4 pool originally has 256 blocks of /8 addresses.
   After the above allocation, there are still 239 blocks of /8
   addresses available to support additional digital communication
   systems, each having the same size of address pool as the allocation
   above. Consequently, many world-wide communication networks may
   coexist under the same IPv4 protocol framework in the form of groups
   of RANs as described earlier, with arm's-length links among them.

      c. For example, a satellite based Internet that is being proposed
   [19], can start fresh with one EzIP RAN served by one SPR having the
   capacity of 256M IoTs, under one ER capable of managing one /8 block
   of IPv4 public address. Utilizing a caching proxy as the gateway to
   handle the data exchange with other RAN, this satellite based
   Internet with 256M hosts can operate pretty much as an isolated
   system by using 240/4 addresses in the basic IP headers for intra-RAN
   communications, most of the time. Only when direct communication with
   another RAN (such as the one for the existing Internet) is needed,
   will the full EzIP header be required. As users grow, additional RANs
   (each with 256M IoTs capacity), may be incrementally added to support
   the expansion.

   G. In summary, utilizing the 240/4 netblock, the EzIP scheme may
   expand the IPv4 based Internet to be a collection of up to 240 groups
   of 16M RANs each managed by one SPR with 256M IoTs capacity that are


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   inter-operable digital communication systems, normally operate at
   arm's-lenghth to one another. Each of these groups has the address
   capacity of at least 80K times of the number of predicted (50B) IoTs
   by Year 2020.



   6. Security Considerations

   The EzIP solution is based on an inline module called SPR that is
   intended to be as transparent to Internet traffic as possible. The
   proposed address assignment rule is deterministic and systematic.
   Thus, no overall system security degradation is expected.



   7. IANA Considerations

   This draft does not create a new registry nor does it register any
   values in existing registries; no IANA action is required.



   8. Conclusions

   To resolve the IPv4 public address pool exhaustion issue, a technique
   called EzIP (phonetic for Easy IPv4) making use of a long reserved
   address block 240/4, is proposed.

   This draft RFC describes an enhancement to IPv4 operation utilizing
   the IP header Option mechanism defined in [RFC791]. Because the
   design criterion is to enhance IPv4 by extending instead of altering
   it, the impact on already in-place routers and security mechanisms is
   minimized.

   The basic EzIP philosophy includes maintaining the existing public
   and private network structure. Upon reclassifying the "RESERVED for
   Future use" 240/4 netblock to be the Semi-Public address pool, it
   will only be usable by the new SPR (Semi-Public Router) as the EzIP
   extension address. This pool can multiply each current IPv4 public
   address 256M fold, while all existing public network and subscriber
   premises setups (private networks as well as directly connected IoTs)
   may remain unchanged. A subscriber is encouraged to upgrade his
   IoT(s) to be EzIP-capable so as to enjoy the enhanced router service
   by EzIP. This particular manifestation of the EzIP scheme appears to
   be the optimal solution to our needs.



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   The 240/4 netblock based EzIP scheme will not only relieve the IPv4
   address shortage, but also improve the defense against cybersecurity
   intrusion by virtue of systematic and deterministic address
   management. The EzIP RAN (Regional Area Network) configuration will
   also support the desire to establish CIR (Country-based Internet
   Registry) operation expressed by ITU-T, as a parallel local parallel
   facility providing services equivalent to the current global
   Internet.

   Furthermore, EzIP will help the IPv4 based Internet to become the
   common backbone for multiple world-wide digital communication systems
   that normally may operate in arm's-length from one another.



   9. References

   9.1. Normative References

   [1]   https://tools.ietf.org/html/rfc791

   [2]   https://tools.ietf.org/html/draft-wilson-class-e-02

   9.2.  Informative References

   [3]   https://www.cisco.com/c/dam/en_us/about/ac79/docs/innov/IoT_IBS
         G_0411FINAL.pdf

   [4]   http://stats.labs.apnic.net/ipv6

   [5]   https://stats.ams-ix.net/sflow/ether_type.html

   [6]   https://tools.ietf.org/html/rfc6598

   [7]   http://www.iana.org/assignments/ipv4-address-space/ipv4-
         address-space.xhtml

   [8]   https://tools.ietf.org/html/rfc1918

   [9]   https://tools.ietf.org/html/rfc793

   [10]  https://www.ietf.org/rfc/rfc2131.txt

   [11]  http://www.iana.org/assignments/ip-parameters/ip-
         parameters.xhtml

   [12]  https://tools.ietf.org/html/rfc1385


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   [13]  https://tools.ietf.org/html/draft-chimiak-enhanced-ipv4-03

   [14]  https://en.wikipedia.org/wiki/Proxy_server#Improving_performanc
         e

   [15]  http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.477.19
         42&rep=rep1&type=pdf

   [16]  https://tools.ietf.org/html/rfc862

   [17]  https://tools.ietf.org/html/rfc2928

   [18]  https://www.nro.net/wp-content/uploads/nro-response-to-ls-5.pdf

   [19]  https://www.commerce.senate.gov/public/index.cfm/2017/10/the-
         commercial-satellite-industry-what-s-up-and-what-s-on-the-
         horizon






   10. Acknowledgments

   The authors would express their deep appreciation to Dr. W. Chimiak
   for the enlightening discussions about his team's efforts and
   experiences through the EnIP development.

   This document was prepared using 2-Word-v2.0.template.dot.



















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Appendix A  EzIP Operation

   To demonstrate how EzIP could support and enhance the Internet
   operations, the following are three sets of examples that involve
   SPRs as shown in Figure 1. These present a general perspective of how
   IP header transitions through the routers may look like.

   1. The first example is between EzIP-unaware IoTs, T1a and T4a. This
   operation is very much the same as the conventional TCP/IP packet
   transmission except with SPRs acting as an extra pair of routers
   providing the CG-NAT service.

   2. The second one is between EzIP-capable IoTs, T1z and T4z. Here,
   the SPRs process the extended semi-public IP addresses in router
   mode, avoiding the drawbacks due to the CG-NAT type of operations
   above.

   3. The last one is between EzIP-unaware and EzIP-capable IoTs. By
   initiating and responding with a conventional IP header, EzIP-capable
   IoTs behave like EzIP-unaware IoTs. Thus, all packet exchanges use
   the conventional IP headers, just like case 1. above.

A.1. Connection between EzIP-unaware IoTs

A.1.1. T1a Initiates a Session Request towards T4a

   T1a sends a session request to SPR4 that serves T4a by a plain IP
   packet with header as in Figure 5, to RG1. There is no TCP port
   number in this IP header yet.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (20)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.3)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 5  IP Header: From T1a to RG1




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A.1.2. RG1 Forwards the Packet to SPR1

     RG1, allowing be masqueraded by T1a, relays the packet toward SPR1
   by assigning the TCP Source port number, 3N, to T1a, with a header as
   in Figure 6,. Note that the suffix "N" denotes the actual TCP port
   number assigned by the RG1's RG-NAT. This could assume multiple
   values, each represents a separate communications session that T1a is
   engaged in. A corresponding entry is created in the RG1 state table
   for handling the reply packet from the Destination site. Since T4a's
   TCP port number is not known yet, it is filled with all 1's.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (240.0.0.0)                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (3N)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 6  TCP/IP Header: From RG1 to SPR1





















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A.1.3. SPR1 Sends the Packet to SPR4 through the Internet

   SPR1, detecting no EzIP Option word, acts like a CG-NAT. It allows
   being masqueraded by RG1 (with the Source Host Number changed to be
   SPR1's  own and the TCP port number changed to 0C, where "0" is the
   last octet of RG1's IP address, and "C" stands for CG-NAT) and sends
   the packet as in Figure 7 out through the Internet towards SPR4. The
   packet traverses through the Internet (ER1, CR and ER4) utilizing
   only the Destination Host Number (word 5) in the header.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (0C)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 7  TCP/IP Header: From SPR1 to SPR4

   Note that although schematically shown in Figure 1 as one public IPv4
   address serving one SPR capable of a full 240/4 address block, the
   PCP port number has a theoretical limit of 64K (256 x 256) because it
   consists of 16 bits. This is much smaller than a full 240/4 pool.
   Even with dynamic assignments, it will take quite a few public
   address to serve the CG-NAT need if many IoTs are EzIP-unaware. So,
   IoTs are encouraged to become EzIP-capable as soon as possible to
   avoid straining the SPR's CG-NAT capability. This should not be an
   issue for emerging regions currently having very little facility and
   IoTs. As new ones are deployed, they should be enabled as EzIP-
   capable by factory default. For the rural area of developed countries
   with existing EzIP-unaware IoTs, the need for CG-NAT service will be
   greater. Multiple IPv4 public addresses would be needed initially to
   support smaller sub- 240/4 netblocks. This is probably workable
   because the latter does have more public IPv4 addresses. The CG-NAT
   techniques developed under [RFC6598] [6] may be incorporated here to
   facilitate the transition.


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A.1.4. SPR4 Sends the Packet to T4a

   Since the packet has a conventional TCP/IP header without Destination
   TCP port number, SPR4 would ordinarily drop it due to the CG-NAT
   function. However, for this example, let's assume that there exists a
   state-table that was set up by a DMZ (De-Militaried Zone) process for
   redirecting this packet to T4a with a CG-NAT TCP port number 10C
   (Here, "10" is the fourth octet of T4a's Extension address, and "C"
   stands for CG-NAT.). After constructing the Destination Host Number
   accordingly, SPR4 sends the packet to T4a with a header as in Figure
   8.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (240.0.0.10)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (0C)        |      Destination Port (10C)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 8  TCP/IP Header: From SPR4 to T4a


















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A.1.5. T4a Replies to SPR4

   T4a interchanges the Source and Destination identifications in the
   incoming TCP/IP packet to create a header as in Figure 9, for the
   reply packet to SPR4.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (240.0.0.10)                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (10C)        |     Destination Port (0C)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 9  TCP/IP Header: From T4a to SPR4
























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A.1.6. SPR4 Sends the Packet to SPR1 through the Internet

   SPR4, allowing being masqueraded by T4a, sends the packet toward SPR1
   with the header in Figure 10, through the Internet (ER4, CR and ER1)
   who will simply relay the packet according to the information in word
   5 (Destination Host Number):

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (10C)        |     Destination Port (0C)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 10 TCP/IP Header: From SPR4 to SPR1























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A.1.7. SPR1 Sends the Packet to RG1

   Using the stored data in the CG-NAT state-table, SPR1 reconstructes a
   header as in Figure 11, for sending the packet to RG1.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (240.0.0.0)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (10C)       |     Destination Port (3N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 11 TCP/IP Header: From SPR1 to RG1

























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A.1.8. RG1 Forwards the Packet to T1a

   From the state-table in RG1's RG-NAT, T1a address is reconstructed
   based on Destination Port (3N), as in Figure 12.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.3)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (10C)        |     Destination Port (3N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 12 TCP/IP Header: From RG1 to T1a

A.1.9. T1a Sends a Follow-up Packet to RG1

   To carry on the communication, T1a constructs a full TCP/IP header as
   in Figure 13 for sending the follow-up packet to RG1.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |                Source Host Number (192.168.1.3)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (69.41.190.148)            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (3N)        |    Destination Port (10C)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 13 TCP/IP Header: Follow-up Packets From T1a to RG1


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A.2. Connection Between EzIP-capable IoTs

   The following is an example of EzIP operation between T1z and T4z
   shown in Figure 1, with full "Public - EzIP : Private" network
   addresses, "69.41.190.110-240.0.0.0:9" and "69.41.190.148-
   246.1.6.40", respectively. Note that T4z, without the private portion
   (TCP port number) in the concatenated address, is directly
   addressable from the Internet. For T1z to initiate a session, it
   needs to know the full address of T4z, but only it's own private
   address.

A.2.1. T1z Initiates a Session Request towards T4z

   T1z sends an EzIP packet, as in Figure 14, to RG1. There is no TCP
   port number word, because T4z does not have such while that for T1z
   is waiting for assignment from the RG1's RG-NAT. Also, the Extended
   Source No. is filled with all "1's", waiting for being specified by
   SPR1.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.9)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (255)  |  No.-2 (255)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |  No.-3 (255)  |  No.-4 (255)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (246)  |   No.-2 (1)   |   No.-3 (6)   |  No.-4 (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 14 EzIP Header: From T1z to RG1



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A.2.2. RG1 Forwards the Packet to SPR1

     RG1, allowing to be masqueraded by T1z, relays a packet as in
   Figure 15,  toward SPR1 by assigning the TCP Source port number, 9N,
   to T1z. Not knowing whether T4z is behind an RG, "All 1's" is used to
   fill the Destination Port part of the TCP word.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (240.0.0.0)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (255)  |  No.-2 (255)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |  No.-3 (255)  |  No.-4 (255)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (246)  |   No.-2 (1)   |   No.-3 (6)   |  No.-4 (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |       Source Port (9N)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 15 TCP/EzIP Header: From RG1 to SPR1











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A.2.3. SPR1 Sends the Packet to SPR4 through the Internet

   SPR1 replaces the Source Host Number with its own as well as fills in
   the Extended Source No. information, and then sends the packet, with
   a header as in Figure 166, out into the Internet towards SPR4. The
   packet traverses through ER1, CR and ER4, utilizing only the
   Destination Host Number (Word 5) in the IP Header.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (240)  |   No.-2 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (0)   |   No.-4 (0)   |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (246)  |   No.-2 (1)   |   No.-3 (6)   |  No.-4 (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |       Source Port (9N)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




               Figure 16 TCP/EzIP Header: From SPR1 to SPR4





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A.2.4. SPR4 Sends the Packet to T4z

   SPR4 reconstructs T4z address from the Option number 0X9B and the
   Extended Destination No. then sends the packet, with the header as in
   Figure 17, to T4z.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (246.1.6.40)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (240)  |   No.-2 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (0)   |   No.-4 (0)   |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (246)  |   No.-2 (1)   |   No.-3 (6)   |  No.-4 (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |       Source Port (9N)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                Figure 17 TCP/EzIP Header: From SPR4 to T4z











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A.2.5. T4z Replies to SPR4

   Making use of the information in the incoming TCP/EzIP header, T4z
   replies to SPR4 with a full header, as in Figure 18.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (246.1.6.40)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (246)  |   No.-2 (1)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (6)   |   No.-4 (40)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (240)  |   No.-2 (0)   |   No.-3 (0)   |   No.-4 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |     Source Port (All 1's)     |     Destination Port (9N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





                Figure 18 TCP/EzIP Header: From T4z to SPR4









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A.2.6. SPR4 Sends the Packet to SPR1 through the Internet

   SPR4 replaces the Source Host Number with its own, and sends the
   packet with the header, as in Figure 19, towards SPR1. The Internet
   (ER4, CR, and ER1) simply relays the packet according to the TCP/EzIP
   header word 5 (Destination Host Number):

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (246)  |   No.-2 (1)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (6)   |   No.-4 (40)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (240)  |   No.-2 (0)   |   No.-3 (0)   |   No.-4 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |     Source Port (All 1's)     |     Destination Port (9N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





               Figure 19 TCP/EzIP Header: From SPR4 to SPR1







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A.2.7. SPR1 Sends the Packet to RG1

   SPR1 reconstructs RG1 address from the Option number 0X9B and the
   Extended Destination No. Then, sends packet with a header as in
   Figure 20 toward RG1.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (240.0.0.0)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (246)  |   No.-2 (1)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (6)   |   No.-4 (40)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (240)  |   No.-2 (0)   |   No.-3 (0)   |   No.-4 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |     Source Port (All 1's)     |     Destination Port (9N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





                Figure 20 TCP/EzIP Header: From SPR1 to RG1






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A.2.8. RG1 Forwards the Packet to T1z

   RG1 reconstructs T1z address from RG1's RG-NAT state-table based on
   Destination Port (9N), then sends the packet to T1z with a header as
   in Figure 21.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.9)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (246)  |   No.-2 (1)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (6)   |   No.-4 (40)  |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (240)  |   No.-2 (0)   |   No.-3 (0)   |   No.-4 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |     Source Port (All 1's)     |     Destination Port (9N)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




                Figure 21 TCP/EzIP Header: From RG1 to T1z







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A.2.9. T1z Sends a Follow-up Packet to RG1

      With all fields filled with needed information from the incoming
   TCP/EzIP header, T1z sends a follow-up packet to RG1 as in Figure 22.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|       Total Length (36)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.9)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |          Destination Host Number (69.41.190.148)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |  No.-1 (240)  |   No.-2 (0)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |   No.-3 (0)   |   No.-4 (0)   |     (0X9B)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |  No.-1 (246)  |   No.-2 (1)   |   No.-3 (6)   |  No.-4 (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     9 |       Source Port (9N)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




       Figure 22 TCP/EzIP Header: Follow-up Packets from T1z to RG1








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A.3. Connection Between EzIP-unaware and EzIP-capable IoTs

A.3.1. T1a Initiates a Request to T4z

   Since T1a can create only conventional format IP header, the SPRs
   will provide CG-NAT type of services to the TCP/IP packets. And,
   assuming SPR4 has a state-table set up by DMZ for forwarding the
   request to T4z, the packet will be delivered to T4z. Seeing the
   incoming packet with conventional TCP/IP header, T4z should respond
   with the same so that the session will be conducted with conventional
   TCP/IP headers. The interaction will follow the same behavior as in
   Appedix A.1.

A.3.2. T1z Initiates a Request to T4a

   Knowing T4a is not capable of EzIP header, T1z purposely initiates
   the request packet using conventional IP header. It will be treated
   by SPRs in the same manner as the T1a initiated case as in Appedix
   A.1. so that the packet will be recognizable by T4a.

Note that to maximize the combination in the EzIP System Architecture
diagram (Figure 1) for demonstrating the possible variations, there is
no RG on Premises 4. IoTs, such as T4a and T4z, are thus directly
connected to a SPR, like SPR4 and there is no corresponding TCP port
number in word 9 of the above TCP/EzIP headers. This spare facility in
the header suggests that an RG may be installed if desired, to establish
the similar private network environment as that on Premises 1.

In brief, the steps outlined above are very much the same as the
conventional TCP/IP header transitions through the Internet with the SPR
providing the CG-NAT service. Except, when a TCP/EzIP header is
detected, the SPR switches to the router mode for forwarding the packet
to improve the performance.

In essence, with the EzIP system architecture very much the same as
today's Internet, the SPR starts with assuming the current CG-NAT duty,
while ready to perform the new EzIP routing function for EzIP-aware
IoTs. This strategy offers a simple transition path for the Internet to
evolve toward the future.

It is important to note that both SPR and CG-NAT are inline devices with
respect to ER. However, since CG-NAT provides soft / ephemeral TCP
ports, it is positioned between a CR and ERs, while SPR is located
between an ER and RGs to assign hard / static physical addresses.





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Appendix B  Internet Transition Considerations

   To enhance a large communication system like the Internet, it is
   important to minimize the disturbance to the existing equipments and
   processes due to any required modification. The basic EzIP plan is to
   confine all actionable enhancements within the new SPR module. The
   following outlines the considerations for supporting the transition
   from the current Internet to the one enhanced by the EzIP technique.

B.1. EzIP Implementation

   B.1.1.   Introductory Phase:

   A. Insert an SPR in front of a web-server that desires to have
   additional subnet addresses for offering diversified activities. For
   the long term, a new web server may be designed with these two
   functional modules combined.

      .  The first address of a private network address pool, e.g.,
   242.0.0.0, used by the SPR should be reserved as a DMZ channel
   directing the initial incoming service requesting packets to the
   existing web server. This will maintain the same current operation
   behavior projected to the general public.

      .  The additional addresses, up to 255.255.255.255 may be used for
   EzIP address extension purposes. Each may be assigned to an
   additional web server representing one of the business's new
   activities. Each of these new servers will then respond with EzIP
   header to messages forwarded from the main server, or be directly
   accessible through its own EzIP address.

   B. Insert an SPR in front of a group of subscribers who are to be
   served with the EzIP capability. The basic service provided by this
   SPR will be the CG-NAT equivalent function. This will maintain the
   same current baseline user experience in accessing the Internet.

   C. Session initiating packets with basic IPv4 header will be routed
   by SPRs to a business's existing server at the currently published
   IPv4 public address (discoverable through existing DNS). The server
   should respond with the basic IPv4 format as well. Essentially, this
   maintains the existing user experience between a customer and a web
   server within an EzIP-unaware environment.

      So far, neither the web-server nor any subscriber's IoTs needs to
   be enhanced, because the operations remain pretty much the same as
   today's common practice utilizing CG-NAT assisted connectivity. See
   Appendix A.1. for an example.


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   D. Upon connection to the main web server, if a customer
   intentionally selects one of the new services, the main web server
   should ask the customer to confirm the selection.

      .  If confirmed, implying that the customer is aware of the fact
   that his IoT is being served by an SPR, the web server forwards the
   request to a branch server for carrying on the session via an EzIP
   address.

      .  The SPR on the customer side, recognizing the EzIP header from
   the branch web-server, replaces the CG-NAT service with the EzIP
   routing.

      .  For all subsequent packets exchanged, the EzIP headers will be
   used in both directions. This will speed up the transmission
   throughput performance for the rest of the session. See Appendix A.2.
   for an example.

   B.1.2.   New IoT Operation Modes:

   A. EzIP-capable IoT will create EzIP header in initiating a session,
   to directly reach a specific EzIP-capable web-server, instead of the
   manual interaction steps of going through the DMZ port then making
   the selection from the main web server. This will speed up the
   initial handshake process. See Appendix A.2. for an example.

   B. To communicate with an EzIP-unaware IoT, an EzIP-capable IoT
   should purposely initiate a session with conventional IP header. This
   will signal the SPRs to provide just the CG-NAT type of connection
   service. See Appendix A.1. for an example.

   B.1.3.   End-to-End Operation:

   Once EzIP-capable IoTs become wide spread among the general public,
   direct communication between any pair of such IoTs will be
   achievable. An EzIP-capable IoT, knowing the other IoT's full EzIP
   address, may initiate a session by creating an EzIP header that
   directs SPRs to provide EzIP service, bypassing the CG-NAT process.
   See Appendix A.2. for an example.

B.2. SPR Operation Logic

   To support the above scenarios, the SPR should be designed with the
   following decision process:

   B.2.1. Sending an IP packet out for an IoT or a RG



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   If the IP header contains EzIP Option word, SPR will route it forward
   by using the EzIP mechanism (replacing Source Host Number by SPR's
   own and filling in Extended Source No. if not already there).
   Otherwise, the SPR provides the CG-NAT service (assigning TCP Source
   Port number and allowing the packet to masquerade with the SPR's own
   IP address, plus creating an entry to the state (port-forward / look-
   up / hash) table in anticipation of the reply packet).

   B.2.2.   Receiving an IP packet from the ER

   If a received IP packet includes a valid EzIP Option word, SPR will
   provide the EzIP routing service (utilizing the Extended Destination
   No. as the Destination Host Number). If only Destination Port number
   is present, CG-NAT service will be provided. For a packet with plain
   IP header (with neither EzIP nor CG-NAT information), it will be
   dropped.

B.3. RG Enhancement

   With IPv4 address pool expanded by the EzIP schemes, there will be
   sufficient publicly assignable addresses for IoTs wishing to be
   directly accessible from the Internet. On the other hand, the
   existing private networks may continue their current behavior of
   blocking session-request packets from the Internet. In-between,
   another connection mode is possible. The following describes such an
   option in the context of the existing RG operation conventions.

   B.3.1.   Initiating Session request for an IoT

   Without regard to whether the IP header is a conventional type or an
   EzIP one, a RG allows a packet to masquerade with the RG's own IP
   address by assigning a TCP port number to the packet and creating an
   entry to the state (port-forward / look-up / hash) table. This is the
   same as the current RG-NAT practice.

   B.3.2.   Receiving a packet from the SPR

   The "Destination Port" value in the packet is examined:

      A. If it matches with an entry in the RG-NAT's state-table, the
   packet is forwarded to the corresponding address. This is the same as
   the normal RG-NAT processes in a conventional RG.

      B. If it matches with the IP address of an active IoT on the
   private network, the packet is assigned with a TCP port number and
   then forwarded to that IoT.



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   Note that there is certain amount of increased security risk with
   this added last step, because a match between a guessed destination
   identity and either of the above two lists could happen by chance. To
   address this issue, the following proactive mechanism should be
   incorporated in parallel:

      C. If the "Destination Port" number is null or matches with
   neither of the above two lists, the packet is dropped and an alarm
   state is activated to monitor for possible ill-intended follow-up
   attempts. A defensive mechanism should be triggered when the number
   of failed attempts has exceeded the preset threshold within a
   predetermined finite time interval.

   In brief, if the IP header of a session requesting packet indicates
   that the sender knows the identity of the desired destination IoT on
   a private network, the common RG screening process will be bypassed.
   This facilitates the direct end-to-end connection, even in the
   presence of the RG-NAT. Note that this process is very much the same
   as the AA (Automated Attendant) capability in a PABX telephone
   switching system that automatically makes the connection for a caller
   who indicates (via proper secondary dialing or an equivalent means)
   knowing the extension number of the destination party. Such process
   effectively screens out most of the unwanted callers while serving
   the acquaintance expeditiously.

























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Appendix C  EzIP Realizability

   The EzIP scheme proposes a new type of network router, called SPR,
   capable of utilizing 240/4 address transported via the Option word
   mechanism in the EzIP Header. In particular, EzIP may optimally be
   first deployed in the form of a Regional Area Network (RAN) wherever
   desired. Each RAN starts from one IPv4 public address to serve up to
   256M IoTs. For such a configuration, an SPR will operate with the
   degenerated EzIP Header which is identical to the basic IPv4 Header,
   except the addresses are from the 240/4 netblock. Since this can be
   accomplished by simply expanding the scope of the accessible address
   pool within the IPv4 protocol, there is hardly any need to modify the
   design of existing routers.

   Having been "Reserved for Future Use" for so long (since 1981-09),
   however, it is a challenge to identify current equipments that may be
   conducive to the use of the 240/4 netblock. Un-documented behaviors,
   observed through extensive research and testing of products in-use
   and on-the-market as well as public domain firmware, confirm that
   certain pairs of router and IoT / PC OS are already partially
   supporting this mode of operation. This unexpected discovery sets the
   baseline for the following interim report.

C.1. 240/4 Netblock Capable IoTs

   A. Open source Xubuntu OS (V.18.04.1) enables a PC to assume both
   dynamic and static IP addresses, simultaneously. The former operates
   in the default DHCP client mode, while the latter accepts manually
   set static addresses including those from the 240/4 netblock. Making
   use of this "dual personality", connectivity between two similarly
   equipped PCs can be established first through a compatible router
   (described in the next subsection) by "ping"ing each other with the
   dynamic address. Using the static 240/4 addresses, the additional
   networking channel through the same router can then be confirmed.

   B. Several other PC OSs, such as Chrome (V.74.0.3729.125), LinuxMint
   V.19 tara (Ubuntu V.4.15.0), Mojave (OSX 10.14.1) and Ubuntu 19.04
   (Ubuntu 5.0.0), have been found to behave similarly, although
   partially and not as conveniently.

C.2. 240/4 Netblock Capable Routers

   A. Open source router firmware OpenWrt (V.18.06.1) currently does not
   utilize the 240/4 netblock in its DHCP operation, while it would not
   reject the process of specifying such. Yet, it transports 240/4
   addressed "ping" packets between two 240/4 capable PCs, anyway.



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   B. Also, a common RG, TP-Link Archer C20 AC750 (F/W V4_170222 /
   0.9.13.16 v0348.0) rejects setting its DHCP pool to use the 240/4
   netblock, but transports 240/4 addressed "ping" packets, nonetheless.

   C. Similarly, Verizon FiOS-G1100 RG (H/W: 1.03, F/W: 02.02.00.14 UI
   Ver: v1.0.388) will not allow its DHCP server to utilize the 240/4
   netblock, but transports the 240/4 addressed "ping" packets, just
   fine.

   D. Other routers, such as LinkSys E3000 (DD-WRT v24-sp2 (05/27/13)
   mini (SVN Rev. 21676), have been found to exhibit similar behavior.

   E. Furthermore, test data suggest that 240/4 addressed "ping" and
   "traceroute" packets from some of the above setups could have
   propagated through an ISP's ER (108.30.229.xxx, Verizon's Edge
   Router) into the Internet. The addresses (130.81.171.xxx) that they
   arrrived at appear to be Verizon's internal routers. If these are not
   CRs (Core Routers), at least they are ARs (Aggregate Routers).

C.3. Enhancing an RG

   The above observations suggest that Xubuntu OS based PCs are likely
   ready to network as 240/4 addressed DHCP clients. To complement this
   capability, we need a router that can function as a 240/4 DHCP
   server. Although the OpenWrt firmware appears to be closer to this
   desired functionality than the TP-Link Router, the source code of the
   latter being hardware specific would better facilitate the firmware
   enhancement efforts. Accordingly, the following outlines the steps
   being planned to bring TP-Link Router and Xubuntu OS based PCs up to
   a state for performing the essential SPR functions:

   C.3.1.   Enhance the TP-Link Router firmware to include the 240/4
   netblock in its DHCP pool.

   C.3.2.   Verify that Xubuntu OS based PCs will accept 240/4 based
   DHCP assignment from the enhanced Router above. With this, deactivate
   the static address settings in the PCs.

   C.3.3.   Send 240/4 destined traffic between two Xubuntu PCs to be
   sure that it is transported through the Router. Three tests will be
   conducted; sending "ping" and "traceroute" packets to confirm the
   basic connectivity as well as file transfer to verify TCP/IP
   capability.

   C.3.4.   A separate second TP-Link Router will then be plugged into
   this first Router as a client IoT to verify that it would accept a
   240/4 address as its WAN port designation. Based on this, the second


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   Router will serve as an RG providing the conventional private network
   environment (10/8, 172.16/12 and 192.168/16 netblocks) to common
   IoTs, allowing them to continue their current operations without
   modification, at all.

C.4. SPR Reference Design

   The above pair of enhanced Routers can be used as the SPR model for
   enahancing industrial grade routers that are capable of the daily
   traffic level expected by a RAN.

   Note that including 240/4 netblock in the DHCP pool for the LAN of
   the first Router and accepting the 240/4 address assignment on the
   WAN port of the second Router are two orthogonal capabilities. They
   can be implemented in the same physical Router, consolidating both
   modifications into one single SPR module.

C.5. RAN Deployment Model

   The above SPR reference design is essentially an existing common IPv4
   RG with two simple enhancements:

   I. Upstream (WAN) port capable of being a DHCP client accepting 240/4
   address assignment, in addition to the ordinary IPv4 public address.

   II.   Downstream (LAN) port providing DHCP service to client IoTs
   using the 240/4 netblock, in addition to the three conventional
   private netblocks.

   By selectively activating these capabilities, three versions of SPRs
   can be derived for completing a functional RAN model:

   C.5.1.   Root / Gateway SPR:     This is the first SPR for starting a
   RAN from an IPv4 public address. As such, the upstream port of this
   SPR should accept a public IPv4 address. And, its downstream port
   will use the 240/4 netblock in its DHCP pool.

   Note that this particular type of SPR is only needed for a RAN
   demonstration setup. In an actual RAN deployment, a proxy gateway
   that caches the Internet traffic for improving the operation
   efficiency will naturally perform the same function of this Root SPR,
   by virtue of being a more capable two-port device.

   C.5.2.   Intermediate SPRs:   To optimize the performance
   requirements on the routing processor, a practical SPR is not
   expected to handle all 256M IoTs in a single module. A RAN should
   have several layers of SPRs in a tree structure, each handles a


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   subset of the 240/4 netblock. This architecture enables processing
   local traffic locally. Only communications with distance parties need
   be consoliated by going through the higher layers of SPRs for
   delivery. For this type of SPRs, both their upstream DHCP client port
   and downstream DHCP Server pool will operate on sub-240/4 netblocks,
   segregated according to the numbering plan in the RAN system design.

   C.5.3.   RG SPR:  To serve existing IoTs on customer premises, this
   SPR will be configured to accept a 240/4 address on its upstream
   port, while the downstream port assigns addresses from the three
   conventional private netblocks to its DHCP client IoTs.






































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Appendix D  Enhancement of a Commercial RG

   Since the 240/4 netblock is just one part of the full IPv4 address
   pool, there is nothing special about it. In principle, all we need to
   do to utilize it is to include it within the usable ranges of a
   router's addresses. However, perhaps because it has been reserved for
   so long, hardly anyone has been paying attention to how the 240/4
   netblock has been treated in current router programs. An intuitive
   assumption is that there may be a database that lists all acceptable
   address ranges or netblocks. If so, the EzIP enhancement would entail
   adding the 240/4 netblock to the list. On the other hand, the current
   approach maybe is based on singling out specific unusable IP
   addresses. Then, eliminationg such process is sufficient. It turns
   out that a commercial RG product appears to be operating with the
   latter approach. From such, the task would become simply commenting
   out the program statements that are rejecting the 240/4 netblock.

D.1. Candidate Code for Modification

   The following short JavaScript function named "ifip" in the TP-Link
   Archer C20 V4 source code has been shown to selectively reject
   specific ranges of IP addresses. In particular, Line 1047 uses a "2's
   Complement" technique to identify the 240/4 netblock as "PRESERVED",
   thus rejecting it. A quick scan of the firmware code in the router
   indicates that this function is a popular utility because there are
   numerous processes calling for it. So, this should be the best
   candidate to start testing our concept.

   lib.js:1040:ifip: function(ip, unalert) {
   lib.js-1041-if ((ip = $.ip2num(ip)) === false) return $.alert(ERR_IP_FORMAT, unalert);
   lib.js-1042-if (ip == -1) return $.alert(ERR_IP_BROADCAST, unalert);
   lib.js-1043-var net = ip >> 24;
   lib.js-1044-if (net == 0) return $.alert(ERR_IP_SUBNETA_NET_0, unalert);
   lib.js-1045-if (net == 127) return $.alert(ERR_IP_LOOPBACK, unalert);
   lib.js-1046-if (net >= -32 && net < -16) return $.alert(ERR_IP_MULTICAST, unalert);
   lib.js-1047-if (net >= -16 && net < 0) return $.alert(ERR_IP_PRESERVED, unalert);
   lib.js-1048-return 0;
   lib.js-1049-},

D.2. Proposed Modification

   To stop rejecting the 240/4 netblock addressed packets, below is a
   modification that comments out Line 1047, a modification that has
   been shown to eliminate javascript pre-validation of 240/4 IP
   addresses, allowing them to be sent within the router, where a second
   layer of validation rejects them in a different way.



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   lib.js:1040:   ifip: function(ip, unalert) {
   lib.js-1041- if ((ip = $.ip2num(ip)) === false) return $.alert(ERR_IP_FORMAT, unalert);
   lib.js-1042- if (ip == -1) return $.alert(ERR_IP_BROADCAST, unalert);
   lib.js-1043-   var net = ip >> 24;
   lib.js-1044- if (net == 0) return $.alert(ERR_IP_SUBNETA_NET_0, unalert);
   lib.js-1045- if (net == 127) return $.alert(ERR_IP_LOOPBACK, unalert);
   lib.js-1046- if (net >= -32 && net < -16) return $.alert(ERR_IP_MULTICAST, unalert);
   lib.js-1047- //if (net >= -16 && net < 0) return $.alert(ERR_IP_PRESERVED, unalert);
   lib.js-1048- return 0;
   lib.js-1049-},

D.3. Performance Verification

   Initially, the TP-Link Archer C20 router's GPL source code package
   from the manufacturer would not go through compilation process. A
   revised version allowed us to build a firmware file. Yet, it failed
   in load into the hardware. Interactions continue with the
   manufacturer hoping to resolve this basic issue soon.































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Authors' Addresses

   Abraham Y. Chen
   Avinta Communications, Inc.
   142 N. Milpitas Blvd., #148, Milpitas, CA 95035-4401 US

   Phone: _+1(408)942-1485
   Email: AYChen@Avinta.com


   Abhay Karandikar
   Director, India Institute of Technology Kanpur
   Kanpur - 208 016, U.P., India

   Phone: _(+91)512 256 7220
   Email: Director@IITK.ac.in


   Ramamurthy R. Ati
   Avinta Communications, Inc.
   142 N. Milpitas Blvd., #148, Milpitas, CA 95035-4401 US

   Phone: _+1(408)458-7109
   Email: rama_ati@outlook.com


   David R. Crowe
   Wireless Telecom Consultant and Forensic Expert Witness
   102 Point Drive NW, Calgary, Alberta, T3B 5B3, Canada

   Phone: _+1(403)289-6609__
   Email: David.Crowe@CNP-wireless.com

















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