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Versions: (draft-boucadair-pcp-rtp-rtcp) 00 01 02 03 04 05 06

Internet Engineering Task Force                                   Q. Sun
Internet-Draft                                             China Telecom
Intended status: Standards Track                            M. Boucadair
Expires: May 24, 2014                                     France Telecom
                                                            S. Sivakumar
                                                           Cisco Systems
                                                                 C. Zhou
                                                     Huawei Technologies
                                                                 T. Tsou
                                               Huawei Technologies (USA)
                                                            S. Perreault
                                                                Viagenie
                                                       November 20, 2013


     Port Control Protocol (PCP) Extension for Port Set Allocation
                       draft-ietf-pcp-port-set-04

Abstract

   This document defines an extension to the Port Control Protocol (PCP)
   allowing clients to manipulate sets of ports as a whole.  This is
   accomplished by a new MAP option: PORT_SET.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Applications Using Port Sets  . . . . . . . . . . . . . .   3
     1.2.  Lightweight 4over6  . . . . . . . . . . . . . . . . . . .   3
     1.3.  Firewall Control  . . . . . . . . . . . . . . . . . . . .   3
     1.4.  Discovering Stateless Port Set Mappings . . . . . . . . .   3
   2.  The need for PORT_SET . . . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  The PORT_SET Option . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Client Behavior . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Server Behavior . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Port Set Renewal and Deletion . . . . . . . . . . . . . .   7
       4.3.1.  Overlap Conditions  . . . . . . . . . . . . . . . . .   8
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Simple Request on NAT44 . . . . . . . . . . . . . . . . .   8
     5.2.  Stateless Mapping Discovery . . . . . . . . . . . . . . .   9
     5.3.  Resolving Overlap . . . . . . . . . . . . . . . . . . . .  10
   6.  Operational Considerations  . . . . . . . . . . . . . . . . .  11
     6.1.  Limits and Quotas . . . . . . . . . . . . . . . . . . . .  11
     6.2.  High Availability . . . . . . . . . . . . . . . . . . . .  11
     6.3.  Idempotence . . . . . . . . . . . . . . . . . . . . . . .  11
     6.4.  What should a PCP client do when it receives fewer ports
           than requested? . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  13
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     11.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   This document extends PCP [RFC6887] with the ability to retrieve a
   set of ports using a single request.  It does so by defining a new
   PORT_SET option.





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   This section describes a few (and non-exhaustive) envisioned use
   cases.  Note that the PCP extension defined in this document is
   generic and is expected to be applicable to other use cases.

1.1.  Applications Using Port Sets

   Some applications require not just one port, but a port set.  One
   example is a Session Initiation Protocol (SIP) User Agent Server
   (UAS) [RFC3261] expecting to handle multiple concurrent calls,
   including media termination.  When it receives a call, it needs to
   signal media port numbers to its peer.  Generating individual PCP MAP
   requests for each of the media ports during call setup would
   introduce unwanted latency.  Instead, the server can pre-allocate a
   set of ports such that no PCP exchange is needed during call setup.

1.2.  Lightweight 4over6

   In the Lightweight 4over6 (lw4o6) [I-D.ietf-softwire-lw4over6]
   architecture, shared global addresses can be allocated to customers.
   It allows moving the Network Address Translation (NAT) function,
   otherwise accomplished by a Carrier-Grade NAT (CGN) [RFC6888], to the
   Customer-Premises Equipment (CPE).  This provides more control over
   the NAT function to the user, and more scalability to the ISP.

   In the lw4o6 architecture, the PCP-controlled device corresponds to
   the lwAFTR, and the PCP client corresponds to the lwB4.  The PCP
   client sends a PCP MAP request containing a PORT_SET option to
   trigger shared address allocation on the lwAFTR.  The PCP response
   contains the shared address information, including the port set
   allocated to the lwB4.

1.3.  Firewall Control

   Port sets are often used in firewall rules.  For example, defining a
   range for RTP [RFC3550] traffic is common practice.  The MAP request
   can already be used for firewall control.  The PORT_SET option brings
   the additional ability to manipulate firewall rules operating on port
   sets instead of single ports.

1.4.  Discovering Stateless Port Set Mappings

   A MAP request can be used to retrieve a mapping from a stateless
   device (i.e., one that does not establish any per-flow state, and
   simply rewrites the address and/or port in a purely algorithmic
   fashion, including no rewriting).  Similarly, a MAP request with a
   PORT_SET request can be used to discover a port set mapping from a
   stateless device.  See Section 5.2 for an example.




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2.  The need for PORT_SET

   Multiple MAP requests can be used to manipulate a set of ports,
   having roughly the same effect as a single use of a MAP request with
   a PORT_SET option.  However, use of the PORT_SET option is more
   efficient when considering the following aspects:

   Network Traffic:  A single request uses less network resources than
      multiple requests.

   Latency:  Even though MAP requests can be sent in parallel, we can
      expect the total processing time to be longer for multiple
      requests than a single one.

   Client-side simplicity:  The logic that is necessary for maintaining
      a set of ports using a single port set entity is much simpler than
      that required for maintaining individual ports, especially when
      considering failures, retransmissions, lifetime expiration, and
      re-allocations.

   Server-side efficiency:  Some PCP-controlled devices can allocate
      port sets in a manner such that data passing through the device is
      processed much more efficiently than the equivalent using
      individual port allocations.  For example, a CGN having a "bulk"
      port allocation scheme (see [RFC6888] section 5) often has this
      property.

   Server-side scalability:  The number of state table entries in PCP-
      controlled devices is often a limiting factor.  Allocating port
      sets in a single request can result in a single mapping entry
      being used, therefore allowing greater scalability.

   Therefore, while it is functionally possible to obtain the same
   results using plain MAP, the extension proposed in this document
   allows greater efficiency, scalability, and simplicity, while
   lowering latency and necessary network traffic.

   In addition, PORT_SET supports parity preservation.  Some protocols
   (e.g. RTP [RFC3550]) assign meaning to a port number's parity.  When
   mapping sets of ports for the purpose of using such kind of protocol,
   preserving parity can be necessary.

3.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].




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4.  The PORT_SET Option

   Option Name:  PORT_SET

   Number:  TBD

   Purpose:  To map sets of ports.

   Valid for Opcodes:  MAP

   Length:  5 bytes

   May appear in:  Both requests and responses

   Maximum occurrences:  1

   The PORT_SET Option indicates that the PCP client wishes to reserve a
   set of ports.  The requested number of ports in that set is indicated
   in the option.

   Note that the option number is in the "optional to process" range
   (128-255), meaning that a MAP request with a PORT_SET option will be
   interpreted by a PCP server that does not support PORT_SET as a
   single-port MAP request, as if the PORT_SET option was absent.

   The PORT_SET Option is formatted as shown in Figure 1.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Option Code=TBD|   Reserved    |        Option Length=5        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Port Set Size          |      First Internal Port      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Reserved   |P|
   +-+-+-+-+-+-+-+-+

                         Figure 1: PORT_SET Option

   The fields are as follows:

   Port Set Size:  Number of ports requested.  MUST NOT be zero.

   First Internal Port:  In a request, this field MUST be set equal to
      the Internal Port field in the MAP opcode by the PCP client.  In a
      response, this field indicates the first internal port of the port
      set mapped by the PCP server, which may differ from the value sent
      in the request.  That is to be contrasted to the Internal Port



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      field, which by necessity is always identical in matched requests
      and responses.

   Reserved:  MUST be set to zero when sending, MUST be ignored when
      receiving.

   P: 1 if parity preservation is requested, 0 otherwise.  See
      [RFC4787], Section 4.2.2.

   The Internal Port Set is defined as being the range of Port Set Size
   ports starting from the First Internal Port.  The External Port Set
   is respectively defined as being the range of Port Set Size ports
   starting from the Assigned External Port.  The two ranges always have
   the same size (i.e., the Port Set Size returned by the PCP server).

4.1.  Client Behavior

   To retrieve a set of ports, the PCP client adds a PORT_SET option to
   its PCP MAP request.  If port preservation is required, the PCP
   Client MUST set the parity bit (to 1) to ask the PCP server to
   preserve the port parity.

   The PCP Client MUST NOT include more than one PORT_SET option in a
   MAP request.  If several port sets are needed, the PCP client MUST
   issue separate MAP requests, each potentially including a PORT_SET
   option.  These individual MAP requests MUST include distinct Internal
   Port.

   If the PCP Client does not know the exact number of ports it
   requires, it MAY then set the Port Set Size to 0xffff, indicating
   that it is willing to accept as many ports as the PCP server can
   offer.

   If no PORT_SET option is present in the response, the PCP client
   cannot conclude that the PCP server does not support the PORT_SET
   option.  It may just be that the PCP server does support PORT_SET but
   decided to allocate only a single port, for reasons that are its own.
   If the client wishes to obtain more ports, it MAY send additional MAP
   requests (see Section 6.4), which the PCP server may or may not grant
   according to local policy.  The presence or absence of the PORT_SET
   attribute in those requests MUST NOT depend on the presence or
   absence of the PORT_SET attribute in previous responses.

   When the PCP-controlled device supports multiple port-sets delegation
   for a given PCP client, the PCP client MAY re-initiate a PCP request
   to get another port set when it has exhausted all the ports within
   the port-set.




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4.2.  Server Behavior

   In addition to regular MAP request processing, the following checks
   are made upon receipt of a PORT_SET option with non-zero Requested
   Lifetime:

   o  If multiple PORT_SET options are present in a single MAP request,
      a MALFORMED_OPTION error is returned.

   o  If the Port Set Size is zero, a MALFORMED_OPTION error is
      returned.

   If the PREFER_FAILURE option is present and the PCP server is unable
   to map all ports in the requested External Port Set or is unable to
   preserve parity (P = 1), the CANNOT_PROVIDE_EXTERNAL error is
   returned.

   If the PREFER_FAILURE option is absent, the PCP server MAY map fewer
   ports than the value of Port Set Size from the request.  It MUST NOT
   map more ports than the PCP client asked for.  Internal ports outside
   the range of Port Set Size ports starting from the Internal Port MUST
   NOT be mapped by the PCP server.

   If the requested port set cannot be fully satisfied, the PCP server
   SHOULD map as many ports as possible, and SHOULD map at least one
   port (which is the same behavior as if Port Set Size is set to 1).

   If the PCP server ends up mapping only a single port, for any reason,
   the PORT_SET option MUST NOT be present in the response.

   If the PREFER_FAILURE option is absent and port parity preservation
   is requested (P = 1), the PCP server MAY preserve port parity.  In
   that case, the External Port is set to a value having the same parity
   as the First Internal Port.

   If the mapping is successful, the MAP response's Assigned External
   Port is set to the first port in the External Port Set, and the
   PORT_SET option's Port Set Size is set to number of ports in the
   mapped port set.  The First Internal Port field is set to the first
   port in the Internal Port Set.

4.3.  Port Set Renewal and Deletion

   Port set mappings are renewed and deleted as a single entity.  That
   is, the lifetime of all port mappings in the set is set to the
   Assigned Lifetime at once.





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   A PCP client attempting to refresh or delete a port set mapping MUST
   include the PORT_SET option in its request.

4.3.1.  Overlap Conditions

   Port set map requests can overlap with existing single port or port
   set mappings.  This can happen either by mistake or after a PCP
   client becomes out of sync with server state.

   If a PCP server receives a MAP request, with or without a PORT_SET
   option, that tries to map one or more internal ports or port sets
   belonging to already existing mappings, then the request is
   considered to be a refresh request applying those mappings.  Each of
   the matching port or port set mappings is processed independently, as
   if a separate refresh request had been received.  The processing is
   as described in Section 15 of [RFC6887].  The PCP server sends a
   Mapping Update message for each of the mappings.

5.  Examples

5.1.  Simple Request on NAT44

   An application requires a range of 100 IPv4 UDP ports to be mapped to
   itself.  The application running on the host has created sockets
   bound to IPv4 UDP ports 50,000 to 50,099 for this purpose.  It does
   not care about which external port numbers are allocated.  The PCP
   client sends a PCP request with the following parameters over IPv4:

   o  MAP opcode

      Mapping Nonce:  <a random nonce>

      Protocol:  17

      Internal Port:  50,000

      Suggested External Port:  0

      Suggested External IP Address:  ::ffff:0.0.0.0

   o  PORT_SET Option

      Port Set Size:  100

      First Internal Port:  50,000

      P:    0




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   The PCP server is unable to fulfill the request fully: it is
   configured by local policy to only allocate 32 ports per user.  Since
   the PREFER_FAILURE option is absent from the request, it decides to
   map UDP ports 37,056 to 37,087 on external address 192.0.2.3 to
   internal ports 50,000 to 50,031.  After setting up the mapping in the
   NAT44 device it controls, it replies with the following PCP response:

   o  MAP opcode

      Mapping Nonce:  <copied from the request>

      Protocol:  17

      Internal Port:  50,000

      Assigned External Port:  37,056

      Assigned External IP Address:  ::ffff:192.0.2.3

   o  PORT_SET Option

      Port Set Size:  32

      First Internal Port:  50,000

      P:    0

   Upon receiving this response, the host decides that 32 ports is good
   enough for its purposes.  It closes sockets bound to ports 50,032 to
   50,099, sets up a refresh timer, and starts using the port range it
   has just been assigned.

5.2.  Stateless Mapping Discovery

   A host wants to discover a stateless NAT44 mapping pointing to it.
   To do so, it sends the following request over IPv4:

   o  MAP opcode

      Mapping Nonce:  <a random nonce>

      Protocol:  0

      Internal Port:  1

      Suggested External Port:  0

      Suggested External IP Address:  ::ffff:0.0.0.0



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   o  PORT_SET Option

      Port Set Size:  65,535

      First Internal Port:  1

      P:    0

   The PCP server sends the following response:

   o  MAP opcode

      Mapping Nonce:  <copied from the request>

      Protocol:  0

      Internal Port:  1

      Assigned External Port:  26,624

      Assigned External IP Address:  ::ffff:192.0.2.5

   o  PORT_SET Option

      Port Set Size:  2048

      First Internal Port:  26,624

      P:    0

   From this response, the host understands that a 2048-port stateless
   mapping is pointing to itself, starting from port 26,624 on external
   IP address 192.0.2.5.

5.3.  Resolving Overlap

   This example relates to Section 4.3.1.

   Suppose internal port 100 is mapped to external port 100 and port set
   101-199 is mapped to external port set 201-299.  The PCP server
   receives a MAP request with Internal Port = 100, External Port = 0,
   and a PORT_SET option with Port Set Size = 100.  The request's
   Mapping Nonce is equal to those of the existing single port and port
   set mappings.  This request is therefore treated as two refresh
   requests, the first one applying to the single port mapping and the
   second one applying to the port set mapping.  The PCP server updates
   both mapping's lifetimes as usual then sends two responses: the first
   one contains Internal Port = 100, External Port = 100, and no



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   PORT_SET option, while the second one contains Internal Port = 101,
   External Port = 201, and a PORT_SET option with Port Set Size = 99.

6.  Operational Considerations

6.1.  Limits and Quotas

   It is up to the PCP server to determine the port-set quota, if any,
   for each PCP client.

   If the PCP server is configured to allocate multiple port-set
   allocations for one subscriber, the same Assigned External IP Address
   SHOULD be assigned to the subscriber in multiple port-set responses.

   To optimize the number of mapping entries maintained by the PCP
   server, it is RECOMMENDED to configure the PCP server to assign the
   maximum allowed port set size in a single response.  This policy
   SHOULD be configurable.

6.2.  High Availability

   The failover mechanism in MAP [section 14 in [RFC6887]] can also be
   applied to port sets.

6.3.  Idempotence

   A core, desirable property of the PCP protocol is idempotence.  In a
   nutshell, requests produce the same results whether they are executed
   once or multiple times.  This property is preserved with the PORT_SET
   attribute, with the following caveat: the order in which the PCP
   server receives requests with overlapping Internal Port Sets will
   affect the mappings being created and the responses received.

   For example suppose these two requests are sent by a PCP client:

   Request A:  Internal Port Set 1-10

   Request B:  Internal Port Set 5-14

   The PCP server's actions will depend on which request is received
   first.  Suppose that A is received before B:

   Upon reception of A:  Internal ports 1-10 are mapped.  A success
      response containing the following fields is sent:

      Internal Port:  1

      First Internal Port:  1



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      Port Set Size:  10

   Upon reception of B:  The request matches mapping A.  The request is
      interpreted as a refresh request for mapping A, and a response
      containing the following fields is sent:

      Internal Port:  5

      First Internal Port:  1

      Port Set Size:  10

   If the order of reception is reversed (B before A), the created
   mapping will be different, and the First Internal Port in both
   responses would then be 5.

   To avoid surprises, PCP clients MUST ensure that port set mapping
   requests do not inadvertently overlap.  For example, a host's
   operating system could include a central PCP client process through
   which port set mapping requests would be arbitrated, Alternatively,
   individual PCP clients running on the same host would be required to
   acquire the internal ports from the operating system (e.g., a call to
   the bind() function from the BSD API) before trying to map them with
   PCP.

6.4.  What should a PCP client do when it receives fewer ports than
      requested?

   Suppose a PCP client asks for 16 ports and receives 8.  What should
   it do?  Should it consider this a final answer?  Should it try a
   second request, asking for 8 more ports?  Should it fall back to 8
   individual MAP requests?  This document does not try to answer those
   questions, but describes issues to be considered when doing so.

   First, the PCP server has decided to allocate 8 ports for some
   reason.  It may be that allocation sizes have been limited by the PCP
   server's administrator.  It may be that the PCP client has reached a
   quota.  It may be that these 8 ports were the last contiguous ones
   available.  Depending on the reason, asking for more ports may or may
   not be likely to actually yield more ports.  However, the PCP client
   has no way of knowing.










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   Second, not all PCP clients asking for N ports actually need all N
   ports to function correctly.  For example, a DNS resolver could ask
   for N ports to be used for source port randomization.  If fewer than
   N ports are received, the DNS resolver will still work correctly, but
   source port randomization will be slightly less efficient, having
   fewer bits to play with.  In that case, it would not make much sense
   to ask for more ports.

   Finally, asking for more ports could be considered abuse.  External
   ports are a resource that is to be shared among multiple PCP clients.
   A PCP client trying to obtain more than its fair share could trigger
   countermeasures according to local policy.

   In conclusion, it is expected that for most applications, asking for
   more ports would not yield benefits justifying the additional costs.

7.  Security Considerations

   The security considerations discussed in [RFC6887] apply to this
   extension.

8.  IANA Considerations

   IANA has allocated value TBD (note to IANA: to be allocated from the
   range 128-191) in the "PCP Options" registry at http://www.iana.org/
   assignments/pcp-parameters for the new PCP option defined in
   Section 4.

9.  Contributors

   The following are extended authors who contributed to the effort:

   Yunqing Chen

   China Telecom

   Room 502, No.118, Xizhimennei Street

   Beijing 100035

   P.R.China

   Chongfeng Xie

   China Telecom

   Room 502, No.118, Xizhimennei Street




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   Beijing 100035

   P.R.China

   Yong Cui

   Tsinghua University

   Beijing 100084

   P.R.China

   Phone: +86-10-62603059

   Email: yong@csnet1.cs.tsinghua.edu.cn

   Qi Sun

   Tsinghua University

   Beijing 100084

   P.R.China

   Phone: +86-10-62785822

   Email: sunqibupt@gmail.com

   Gabor Bajko

   Nokia

   Email: gabor.bajko@nokia.com

   Xiaohong Deng

   France Telecom

   Email: xiaohong.deng@orange-ftgroup.com

10.  Acknowledgements

   The authors would like to show sincere appreciation to Alain Durand,
   Cong Liu, Dan Wing, Dave Thaler, Peter Koch, Reinaldo Penno, Sam
   Hartman, Stuart Cheshire, Ted Lemon, and Yoshihiro Ohba, for their
   useful comments and suggestions.





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11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.

11.2.  Informative References

   [I-D.cheshire-recursive-pcp]
              Cheshire, S., "Recursive PCP", draft-cheshire-recursive-
              pcp-02 (work in progress), March 2013.

   [I-D.ietf-softwire-lw4over6]
              Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and
              I. Farrer, "Lightweight 4over6: An Extension to the DS-
              Lite Architecture", draft-ietf-softwire-lw4over6-03 (work
              in progress), November 2013.

   [I-D.tsou-stateless-nat44]
              Tsou, T., Liu, W., Perreault, S., Penno, R., and M. Chen,
              "Stateless IPv4 Network Address Translation", draft-tsou-
              stateless-nat44-02 (work in progress), October 2012.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC4787]  Audet, F. and C. Jennings, "Network Address Translation
              (NAT) Behavioral Requirements for Unicast UDP", BCP 127,
              RFC 4787, January 2007.

   [RFC6888]  Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
              and H. Ashida, "Common Requirements for Carrier-Grade NATs
              (CGNs)", BCP 127, RFC 6888, April 2013.

Authors' Addresses





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Internet-Draft                PCP PORT_SET                 November 2013


   Qiong Sun
   China Telecom
   P.R.China

   Phone: 86 10 58552936
   Email: sunqiong@ctbri.com.cn


   Mohamed Boucadair
   France Telecom
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com


   Senthil Sivakumar
   Cisco Systems
   7100-8 Kit Creek Road
   Research Triangle Park, North Carolina  27709
   USA

   Phone: +1 919 392 5158
   Email: ssenthil@cisco.com


   Cathy Zhou
   Huawei Technologies
   Bantian, Longgang District
   Shenzhen  518129
   P.R. China

   Email: cathy.zhou@huawei.com


   Tina Tsou
   Huawei Technologies (USA)
   2330 Central Expressway
   Santa Clara, CA 95050
   USA

   Phone: +1 408 330 4424
   Email: Tina.Tsou.Zouting@huawei.com








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   Simon Perreault
   Viagenie
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Phone: +1 418 656 9254
   Email: simon.perreault@viagenie.ca











































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