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<Network Working Group>                                       A. Y. Chen
Internet Draft                                                 R. R. Ati
Intended status: Experimental                Avinta Communications, Inc.
Expires June 2019                                          A. Karandikar
                                           India Institute of Technology
                                                             David Crowe
                                  Cellular Networking Perspectives, Ltd.

                      Adaptive IPv4 Address Space
          <draft-chen-ati-adaptive-ipv4-address-space-04.txt>

Status of this Memo

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Abstract




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   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 this system.

   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 EzIP as address expansion using 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 by 512M times 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.















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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  . . . . . . . . . . . . . . . . .  8
     2.4. IP Header with Option Word  . . . . . . . . . . . . . . . . 10
     2.5. Examples of Option Mechanism  . . . . . . . . . . . . . . . 11
     2.6. EzIP Header . . . . . . . . . . . . . . . . . . . . . . . . 12
     2.7. EzIP Operation  . . . . . . . . . . . . . . . . . . . . . . 13
   3.  EzIP Deployment Strategy . . . . . . . . . . . . . . . . . . . 13
   4. Updating Servers to Support EzIP  . . . . . . . . . . . . . . . 15
   5. EzIP Enhancement and Application  . . . . . . . . . . . . . . . 16
   6. Security Considerations . . . . . . . . . . . . . . . . . . . . 20
   7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 20
   8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 20
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 21
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 21
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 22
   Appendix A EzIP Operation  . . . . . . . . . . . . . . . . . . . . 23
     A.1. Connection between EzIP-unaware IoTs  . . . . . . . . . . . 23
       A.1.1. T1a Initiates a Session Request towards T4a . . . . . . 23
       A.1.2. RG1 Forwards the Packet to SPR1 . . . . . . . . . . . . 24
       A.1.3. SPR1 Sends the Packet to SPR4 through the Internet  . . 25
       A.1.4. SPR4 Sends the Packet to T4a  . . . . . . . . . . . . . 26
       A.1.5. T4a Replies to SPR4 . . . . . . . . . . . . . . . . . . 27
       A.1.6. SPR4 Sends the Packet to SPR1 through the Internet  . . 27
       A.1.7. SPR1 Sends the Packet to RG1  . . . . . . . . . . . . . 28
       A.1.8. RG1 Forwards the Packet to T1a  . . . . . . . . . . . . 28
       A.1.9. T1a Sends a Follow-up Packet to RG1 . . . . . . . . . . 29
     A.2. Connection Between EzIP-capable IoTs  . . . . . . . . . . . 29
       A.2.1. T1z Initiates a Session Request towards T4z . . . . . . 30
       A.2.2. RG1 Forwards the Packet to SPR1 . . . . . . . . . . . . 31
       A.2.3. SPR1 Sends the Packet to SPR4 through the Internet  . . 32
       A.2.4. SPR4 Sends the Packet to T4z  . . . . . . . . . . . . . 33
       A.2.5. T4z Replies to SPR4 . . . . . . . . . . . . . . . . . . 34
       A.2.6. SPR4 Sends the Packet to SPR1 through the Internet  . . 35
       A.2.7. SPR1 Sends the Packet to RG1  . . . . . . . . . . . . . 36
       A.2.8. RG1 Forwards the Packet to T1z  . . . . . . . . . . . . 37
       A.2.9. T1z Sends a Follow-up Packet to RG1 . . . . . . . . . . 38
     A.3. Connection Between EzIP-unaware and EzIP-capable IoTs . . . 38
       A.3.1. T1a Initiates a Request to T4z  . . . . . . . . . . . . 38
       A.3.2. T1z Initiates a Request to T4a  . . . . . . . . . . . . 39
   Appendix B Internet Transition Considerations  . . . . . . . . . . 40
     B.1. EzIP Implementation . . . . . . . . . . . . . . . . . . . . 40



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       B.1.2. New IoT Operation Modes:  . . . . . . . . . . . . . . . 41
       B.1.3. End-to-End Operation: . . . . . . . . . . . . . . . . . 41
     B.2. SPR Operation Logic . . . . . . . . . . . . . . . . . . . . 41
     B.3. RG Enhancement  . . . . . . . . . . . . . . . . . . . . . . 42
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43

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
   amount of time for 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 address
   (4,294,967,296 decimal exact).

   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
   should be capable of. Being dynamic, the state-table used by CGN
   increases CyberSecurity vulnerability. Because port numbers are used
   to effectively increase the size of the address pool, they introduce
   complex and sub-optimal port management requirements

   If IPv4 capacity could be expanded without the size and efficiency
   limitations of NAT, the urgency will be relaxed long enough for the



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   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 address block 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 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 utilizing the current
   Internet system architecture. Its deployment will start with an SPR
   providing public NAT functions, in a new way, to unload the burden
   from the current CGN. With basic routing as an integral part of the
   SPR, individual IoTs, or other large networks, will be encouraged to
   migrate toward full EzIP service which provides end-to-end
   connectivity between private premises.

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, a
   several ways to expand the publicly assignable IPv4 address pool, as
   well as enhance Internet operations are then discussed.














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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) switches
   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.

   PABX extension numbers belong to a reusable private set. For example,
   extension 123 or 1234 may exist in thousands of different PABX
   switches without ambiguity. Similarly, the IPv4 private network
   address 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 192.18.K/24 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 192.18/16 block, as the factory default
   RG identification assigned by a manufacturer, is implicitly capable
   of expanding it by 256 fold for supporting a corresponding number of
   private premises.

   A key EzIP concept is to use the elusive IPv4 240/4 block (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 redesignate it for "Private Use" near 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, 240/4
   remain reserved for future use.

   Substituting the function of the third octet of 192.168.K/24 with
   addresses from the 240/4 block 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



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   factor of 256M without involving any existing router. This is because
   the 240/4 addresses are only used within the RG SPR and within the
   OPTION header extension, they are not used as IPv4 addresses within
   the  internet. These addresses are equivalent to PABX extension
   numbers, with the additional advantage that IPv4 OPTION header
   extensions can carry them through the network.

   Since the 240/4 block cannot be used by existing routers, the size of
   the 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

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

   NAT works by temporarily assigning a port number to outgoing
   communications from a private address, while converting the private
   address 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 private IPv4 address.

   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 but
   there are so many EzIP addresses that assignments can be made for a
   much longer period of time (days or months rather than seconds or
   minutes); (3) Port numbers are used for other purposes than NAT,
   further reducing the pool, but EzIP uses 240/4 addresses for only 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 with EzIP the address assignments will be long
   term and could be used for direct communications from EzIP-aware
   devices.














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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 positioned 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 block will 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.





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   2.2.1. Referring to the left-hand 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
   block 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.

   2.2.2. Part of the right-hand 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 block to T4a and T4z, respectively.
   Consequently, these IoTs are accessible through SPR4 from any other
   IoT in the Internet.

   2.2.3. 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.

   2.2.4. 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

   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
   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



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   shall be avoided in actual practice by following the 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 of [RFC791] is utilized
   to carry the addresses as 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
   hexadecimal number, "0x9A", is conventionaly written in the binary
   bit string form as "1001 1010". As Opt. Code, however, the eight bits
   are parsed into three groups of 1, 2 and 5 bits "1 00 11010" with
   meanings described in Figure 3.












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      +--------------------------------------------------------------+
      |           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).

   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.



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      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 NAT in an RG 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 (Four octet)

   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 block 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 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.






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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

   There are no security considerations relevant to this document.

   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 CGN 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 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



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   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 Deployment

   C.1. Since the size of the 240/4 block 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 [3], a 240/4 block is capable of serving nearly
   39M (256M / 6.6) people. This exceeds the population of the largest
   city on earth (33M - 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 "RAN" utilizing SPRs operating with
   one 240/4 block of addresses under one IPv4 public address. If the
   gateway for a region is configured in such a way that the entire
   region appears to be one ordinary IPv4 IoT to the rest of the
   Internet, a RAN may be deployed anywhere there is the need or desire,
   with no perturbation to the current Internet operation 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
   minimizing Internet traffic for data exchanges with the central 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 relevant
   subsets). 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 web server access, and intra-regional



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   messaging.

   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 addresses
   from the 240/4 block) will be suffice for intra RAN traffic. This
   mirrors the dialing procedure 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 that identifies the PABX to the PSTN.

   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 that have been used in the PABX field for many
   years.

   C.5. The above would streamline the CIR (Country-based Internet
   Registry) model proposed by ITU-T [18]. 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 conforms to local preferences. This
   scheme estqablishes a second Internet service parallel to the
   existing one for demonstrating their respective merits independently,
   offering subscribers true options to choose from.

   D. Permanently

   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



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   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 position, 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 for 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
   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 [12].

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



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   pool be freely re-allocatable, the assignable public address pool
   could be expanded significantly more, as outlined below.

   A. If the 240/4 block 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 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 of the rest 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
   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 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.



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   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 CGN
      service. Applying all of these to the entire IPv4 pool of 4B
      addresses, the maximum effective CGN 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 block with 256M addresses in the EzIP
      extension scheme, a /6 block with 64M addresses from the IPv4
      basic 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 by carrying out this preparatory phase on
      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 (about 190 out of
      233, or about 80%) countries should be able to port all of their
      respective predicted IoTs to be under one 240/4 block, 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



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      plentifull 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 without.

      e. As IoTs getting migrated to the temporary pool, the IPv4
      addresses they originally occupy shall be released to re-populate
      the public address pool for establishing the 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
      block will be served by two (or more) 240/4 blocks. Then, each of
      such 240/4 block 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 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 block, 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



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      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 caching proxy as the
      gateway to handle the data exchange with other RAN, this satellite
      based Internet with 256M hosts will 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, full EzIP header will be used. 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 address block, 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
   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
   intends to be as transparent to the Internet traffic as possible.
   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



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   impact on already in-place routers and security mechanisms is
   minimized.

   The basic EzIP philosophy includes maintaining the existing private
   network configuration. Upon reclassifying the "RESERVED for Future
   use" 240/4 block 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 by
   256M times, 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.

   The 240/4 block based EzIP scheme will not only relief the IPv4
   address shortage issue, but also improve the defense against
   cybersecurity intrusion by virtue of systematic address management.
   The EzIP' RAN (Regional Area Network) configuration will also support
   the desire to establish CIR operation expressed by ITU-T, as a
   parrellel facility to provide Internet type services by individual
   entities versus the current global model.

   Furthermore, the EzIP will transcend the IPv4 based Internet to
   become the common backbone for multiple world-wide digital
   communication systems that normally may operate at 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_IBSG_0411FINAL.pdf

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

   [5] https://ams-ix.net/technical/statistics/sflow-stats/ether-type

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

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



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   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

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

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

   [15]
   http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.477.1942&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 and 3-
   nroff.template.














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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 CGN 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 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 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 CGN. 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 CGN) 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 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 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 blocks. This is probably workable because
   the latter does have more public IPv4 addresses. The CG-NAT
   techniques developed under RFC6264 [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 CGN
   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 CGN TCP port number 10C (Here,
   "10" is the fourth octet of T4a's Extension address, and "C" stands
   for CGN.). 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

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 CGN state-table, SPR1 reconstructs 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

A.1.8. RG1 Forwards the Packet to T1a

   From the state-table in RG1's 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










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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


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.



















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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 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 16, 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 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 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

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 CGN 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.





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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 CGN 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 CGN 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 CGN are inline devices with
   respect to ER. However, since CGN 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 CGN 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 CGN assisted connectivity. See
   Appendix A.1.  for an example.




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   D. Upon connected 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 CGN 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.

      in 3
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 CGN 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 CGN 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 CGN 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, CGN service will be provided.
      For a packet with plain IP header (with neither EzIP nor CGN
      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 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 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:

      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 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 has effectively
      screened out most of the unwanted callers while serves the
      acquaintance expeditiously.

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 Crowe
      Wireless Telecom Consultant and Forensic Expert Witness



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      102 Point Drive NW, Calgary, Alberta, T3B 5B3, Canada
      Phone: _+1(403)289-6609
      Email: David.Crowe@cnp-wireless.com
















































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