Internet DRAFT - draft-boucadair-pcp-sip-ipv6
draft-boucadair-pcp-sip-ipv6
Network Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Informational R. Parthasarathi
Expires: May 29, 2016 Nokia Networks
November 26, 2015
Port Control Protocol (PCP) for SIP Deployments in Managed Networks
draft-boucadair-pcp-sip-ipv6-07
Abstract
This document discusses how PCP (Port Control Protocol) can be used
in SIP deployments in managed networks. This document applies for
both IPv4 and IPv6.
Status of This Memo
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This Internet-Draft will expire on May 29, 2016.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. PCP Features . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Learn External IP Address and Port Number . . . . . . . . 4
2.2. Learn and Set the Lifetime of Mapping Entries . . . . . . 6
2.3. Allow Unidirectional Media Flows . . . . . . . . . . . . 6
2.4. Preserve Port Parity . . . . . . . . . . . . . . . . . . 7
2.5. Preserve Port Contiguity . . . . . . . . . . . . . . . . 7
2.6. Learn PREFIX64 . . . . . . . . . . . . . . . . . . . . . 8
2.7. Compliant with "a=rtcp" Attribute . . . . . . . . . . . . 10
2.8. DSCP Marking Policy . . . . . . . . . . . . . . . . . . . 10
3. Avoid Crossing CGNs . . . . . . . . . . . . . . . . . . . . . 11
3.1. Avoid NAT64 . . . . . . . . . . . . . . . . . . . . . . . 11
3.2. Avoid Crossing DS-Lite AFTR . . . . . . . . . . . . . . . 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The base Port Control Protocol (PCP, [RFC6887]) specification allows
to retrieve the external IP address and external port to be conveyed
in the SIP signaling messages [RFC3261]. Therefore, SIP Proxy
Servers do not need to support means to ease the NAT traversal of SIP
messages (e.g., [RFC5626], [RFC6223], etc.). Another advantage of
using the external IP address and port is this provides a hint to the
proxy server there is no need to return a small expire timer (e.g.,
60s). In addition, the outbound proxy does not need any further
feature to be supported in order to assist the remote endpoint to
successfully establish media sessions. In particular, ALGs are not
required in the NAT for this purpose and no dedicated functions at
the media gateway are needed.
This document discusses how PCP can be used in SIP deployments
(including IPv6 considerations).
The benefits of using PCP for SIP deployments are listed below:
o Avoid embedding an ALG in the middleboxes. Note, ALGs are not
recommended since the evolution of the service would depend on the
ALG maintenance.
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o Not require any Hosted NAT Traversal function (e.g., [RFC7362]) to
be embedded in the SIP server. Intermediate NATs and firewalls
are transparent to the SIP service platform.
o Avoid overloading the network with keepalive message to maintain
the mapping in intermediate middleboxes.
Note, mechanisms such as STUN do not allow to discover the
lifetime assigned by the middleboxes; frequent keepalive messages
are therefore generated to maintain binding entries on those
middleboxes. PCP is superior to those mechanisms as it allows to
retrieve the assigned lifetime, and to provide hints to the
middleboxes in order to decide which lifetime value is to be
assigned for that particular flow.
o Work without requiring symmetric RTP/RTCP [RFC4961].
o Not require symmetric SIP to work (i.e., rport [RFC3581]).
o Easily support unidirectional sessions.
o Does not encounter issues with early media.
o The combination of PCP and ALTC [RFC6947] allows to optimize
IPv4-IPv6 interworking function resources.
o Because there is no need for connectivity checks, session
establishment delay is not impacted (pairs of ports can be pre-
reserved).
o The binding entries maintained by a flow-aware device (NAT/
Firewall) can be associated with a textual description
([RFC7220]).
Experimentation results, including SIP flow examples, are documented
in [I-D.boucadair-pcp-nat64-experiments].
In deployments where ICE [RFC5245] is required, PCP can be of great
help as discussed in [I-D.penno-rtcweb-pcp] for the WebRTC case. ICE
can be used in the context of SIP over WebSocket [RFC7118] and WebRTC
when deployed within managed networks. Because TURN suffers from
limitations in traversing NAT and firewalls over UDP, PCP is a
promising solution that can complement ICE in those deployment
contexts to soften the experienced high failure rate [ICEFailure].
The document targets SIP deployments in managed networks. It can
also be used as part of SIP-based services delivery in the context of
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network-located residential gateway effort [WT-317]. Typical
deployment scenarios are shown in Figure 1.
(a) SIP UA behind a NAT/FW communicating with a Proxy Server
__________
+----------+ +----------+ / \ +------------+
| SIP UA |___| NAT/FW |____| Network |___| SIP Proxy |
|PCP Client| |PCP Server| | | | Server |
+----------+ +----------+ \__________/ +------------+
(b) SIP UA behind a NAT/FW communicating with a remote SIP UA
__________
+----------+ +----------+ / \ +------------+
| SIP UA |___| NAT/FW |____| Network |___| SIP UA |
|PCP Client| |PCP Server| | | | |
+----------+ +----------+ \__________/ +------------+
(c) SIP UAs behind a NATs/FWs
__________
+----------+ +----------+ / \ +----------+ +----------+
| SIP UA |__| NAT/FW |__| Network |__| NAT/FW |__| SIP UA |
|PCP Client| |PCP Server| | | |PCP Server| |PCP Client|
+----------+ +----------+ \__________/ +----------+ +----------+
(d) SIP UA behind a CPE: PCP Proxy
+----------+ +---------+ +----------+
| SIP UA |____| CPE |__________| CGN/FW |
|PCP Client| |PCP Proxy| |PCP Server|
+----------+ +---------+ +----------+
Figure 1: Typical deployment scenarios
The PCP server can be provisioned using a variety of means (e.g.,
[RFC7291]) or rely on the discovery method specified in [RFC6887].
This document does not make any assumption whether the PCP client is
implemented as an OS service or whether it is integrated in the SIP
User Agent (UA). Those considerations are implementation-service.
2. PCP Features
2.1. Learn External IP Address and Port Number
The PCP base specification allows to create mappings in PCP-
controlled devices and therefore prepare for receiving incoming
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packets. A SIP UA can use PCP to create one mapping for SIP
signalling messages and other mappings for media session purposes.
The SIP UA uses the external IP address and port number to build SIP
headers. In particular, this information is used to build the VIA
and CONTACT headers.
Figure 2 shows an example of the flow exchange that occurs to
retrieve the external IP address and an external IP address assigned
by the NAT, while Figure 2 provides an excerpt of the SIP REGISTER
message issued by the SIP UA; only the assigned IP address and port
number are present in the SIP headers.
+---------+ +-------+ +------------+
| SIP UA | | NAT | | IPv4 SIP |
| PCP | |+ PCP | |Proxy Server|
| Client | |Server | | "Mysip.fr" |
+---------+ +-------+ +------------+
| (a) PCP MAP | |
|Suggested External IP@ | |
| ::ffff:0.0.0.0| |
|Suggested External Port| |
| 5060| |
|======================>| |
| (b) PCP MAP | |
|Suggested External IP@ | |
| ::ffff:192.0.2.1| |
|Suggested External Port| |
| 3938| |
|<======================| |
| (1)SIP REGISTER |(2)SIP REGISTER |
|======================>|===============>|
| (4) SIP 200 OK | (3) SIP 200 OK |
|<======================|<===============|
| | |
Figure 2: SIP REGISTER Call Flow
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SIP Message:
REGISTER sip:mysip.fr SIP/2.0
Via: SIP/2.0/UDP 192.0.2.1:3938;branch=z9hG4bK1572043597
From: <sip:client4@mysip.fr:5070>;tag=893886783
To: <sip:client4@mysip.fr:5070>
Call-ID: 1271173454
CSeq: 2 REGISTER
Contact: <sip:client4@192.0.2.1:3938;line=b3433a7df33282d>
Authorization: Digest username="client4", realm="asterisk",
nonce="09f75e47", uri="sip:mysip.fr",
response="826fcff4c6e84ee45fbfa52c351e6316", algorithm=MD5
Max-Forwards: 70
User-Agent: Linphone/3.4.0 (eXosip2/unknown)
Expires: 3600
Figure 3: Example of REGISTER messager
The external IP address and port(s) instantiated for media streams,
are used to build the SDP offer/answer. In particular, the "c" line
and "m" lines.
2.2. Learn and Set the Lifetime of Mapping Entries
PCP allows to discover and to set the lifetime of mapping
instantiated in intermediate middleboxes.
The discovery of the lifetime of a mapping avoids overloading the
network and SIP servers with frequent messages. This is in
particular important for cellular devices. According to [Power], the
consumption of a cellular device with a keep-alive interval equal to
20 seconds (that is the default value in [RFC3948] for example) is 29
mA (2G)/34 mA (3G). This consumption is reduced to 16 mA (2G)/24 mA
(3G) when the interval is increased to 40 seconds, to 9.1 mA (2G)/16
mA (3G) if the interval is equal to 150 seconds, and to 7.3 mA
(2G)/14 mA (3G) if the interval is equal to 180 seconds. When no
keep-alive is issued, the consumption would be 5.2 mA (2G)/6.1 mA
(3G). The impact of keepalive messages would be more severe if
multiple applications are issuing those messages (e.g., SIP, IPsec,
etc.).
2.3. Allow Unidirectional Media Flows
As a consequence of instantiating mappings for media/session flows,
incoming packets can be successfully forwarded to the appropriate SIP
UA. Particularly, unidirectional media flows (e.g., announcement
server) will be forwarded accordingly.
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2.4. Preserve Port Parity
For deployments relying on classic RTP/RTCP odd/even port numbers
assignment scheme, PORT_SET option [I-D.ietf-pcp-port-set] can be
used by a SIP UA to request port parity be preserved by the PCP
server.
An example is depicted in Figure 4.
2.5. Preserve Port Contiguity
For deployments assuming RTCP port number can be deduced from the RTP
port number, PORT_SET option [I-D.ietf-pcp-port-set] can be used by a
SIP UA to retrieve a pair of contiguous ports from the PCP server.
A flow example is shown in Figure 4.
+---------+ +-------+ +------------+
| SIP UA | | NAT | | IPv4 SIP |
| PCP | |+ PCP | |Proxy Server|
| Client | |Server | | "Mysip.fr" |
+---------+ +-------+ +------------+
| (a) PCP MAP | |
|Suggested External IP@ | |
| ::ffff:192.0.2.1| |
|Suggested External Port| |
| 6000| |
| PORT_SET: | |
| "P" bit set to 1 | |
| Port Set Size=2 | |
|======================>| |
| (b) PCP MAP | |
|Assigned External IP@ | |
| ::ffff:192.0.2.1| |
|Assigned External Port | |
| 7076| |
| PORT_SET: | |
| "P" bit set to 1 | |
| Port Set Size=2 | |
|<======================| |
| | |
Figure 4: Retrieve a pair of ports that preserves port parity
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2.6. Learn PREFIX64
If the SIP UA is located behind a NAT64 device [RFC6146], the option
defined in [RFC7225] can be used to retrieve the PREFIX64 used by
that NAT64 device.
The retrieved prefix will be used to locally build an IPv6-converted
IPv4 address ([RFC6052]) corresponding to the IPv4 address included
in the SDP message received from a remote IPv4-enabled SIP UA; the
SDP message can be an SDP offer or an answer.
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+---------+ +-----+ +------------+ +---------+
|IPv6-only| |NAT64| | IPv4 SIP | |IPv4-only|
| SIP UA | | | |Proxy Server| | SIP UA |
+---------+ +-----+ +------------+ +---------+
| (a) PCP MAP Request | | |
|Suggested External IP@ | | |
| ::ffff:192.0.2.1| | |
|Suggested External Port| | |
| 6000| | |
| PORT_SET | | |
| PREFIX64 | | |
|======================>| | |
| (b) PCP MAP Response | | |
|Assigned External IP@ | | |
| ::ffff:192.0.2.1| | |
|Assigned External Port | | |
| 7076| | |
| PORT_SET | | |
| PREFIX64: | | |
| 2001:db8:122::/48 | | |
|<======================| | |
| (1) SIP INVITE | (2) SIP INVITE | (3) SIP INVITE |
|======================>|===============>|================>|
| (6) SIP 200 OK | (5) SIP 200 OK | (4) SIP 200 OK |
|<======================|<===============|<================|
| (7) SIP ACK | (8) SIP ACK | (9) SIP ACK |
|======================>|===============>|================>|
| | | |
|src port: dst port:|src port: dst port:|
|6000 port_B|7076 port_B|
|<======IPv6 RTP=======>|<============IPv4 RTP============>|
|<===== IPv6 RTCP======>|<============IPv4 RTCP===========>|
|src port: dst port:|src port: dst port:|
|6001 port_B+1|7077 port_B+1|
| | |
Figure 5: Example of IPv6 to IPv4 SIP-Initiated Session
Figure 6 shows the content of the SIP INVITE message sent by the
IPv6-only SIP UA. This message uses the retrieved external IP
address and external port numbers in SIP headers and SDP lines. This
message is translated by the NAT64 without altering the SIP/SDP
content.
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INVITE sip:13@mysip.fr:5070 SIP/2.0
Via: SIP/2.0/UDP 192.0.2.1:56252;branch=z9hG4bK1876803184
From: <sip:client4@mysip.fr:5070>;tag=631384602
To: <sip:13@mysip.fr:5070> Call-ID: 1377792765 CSeq: 21 INVITE
Contact: <sip:client4@192.0.2.1:56252>
Authorization: Digest username="client4", realm="asterisk",
nonce="3358d80b", uri="sip:13@mysip.fr:5070",
response="41442e94f6610e6f383a355a1bdf3e48", algorithm=MD5
Content-Type: application/sdp Allow: INVITE, ACK, CANCEL, OPTIONS,
BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO
Max-Forwards: 70
User-Agent: Linphone/3.4.0 (eXosip2/unknown)
Subject: Phone call Content-Length: 443
v=0
o=client4 2487 2487 IN IP4 192.0.2.1
s=Talk c=IN IP4 192.0.2.1
b=AS:256
t=0 0
m=audio 7076 RTP/AVP 111 110 3 101
a=rtpmap:111 speex/16000
a=fmtp:111 vbr=on a=rtpmap:110 speex/8000
a=fmtp:110 vbr=on a=rtpmap:3 GSM/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-11
m=video 9076 RTP/AVP 102 99
a=rtpmap:102 H264/90000
a=fmtp:102 profile-level-id=428014
a=rtpmap:99 MP4V-ES/90000
a=fmtp:99
profile-level-id=3
Figure 6: Content of the INVITE message
2.7. Compliant with "a=rtcp" Attribute
The base PCP specification can be used to retrieve the port number to
be singled if "a=rtcp" attribute is in use [RFC3550].
2.8. DSCP Marking Policy
PCP can be used to discover the DSCP value to be used when sending
real-time flows or to create a mapping that matches a DSCP marking.
This can be achieved using the DSCP option defined in
[I-D.boucadair-pcp-extensions]. DSCP setting value is configured by
the network and not the SIP UA.
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This feature can be used as an input for DSCP marking in some
deployments such as [I-D.ietf-tsvwg-rtcweb-qos].
3. Avoid Crossing CGNs
3.1. Avoid NAT64
Because an IPv6-only SIP UA is not aware of the connectivity
capabilities of the remote UA, the IPv6-only SIP UA uses the ALTC
attribute [RFC6947] to signal the assigned IPv6 address and the IPv4
address learned via PCP.
If the remote SIP UA is IPv6-enabled, IPv6 transfer capabilities will
be used to place the session. If the remote SIP UA is IPv4-only,
IPv4 transfer capabilities will be used. NAT64 devices will be
crossed only if the remote UA is IPv4-only.
Figure 7 provides an except of a SIP INVITE message that encloses
both the local IPv6 address and the IPv4 address/port number assigned
by a NAT64 device.
INVITE sip:13@mysip.fr:5070 SIP/2.0
Via: SIP/2.0/UDP 192.0.2.1:35011;branch=z9hG4bK702695557
From: <sip:client4@mysip.fr:5070>;tag=641336337
To: <sip:13@mysip.fr:5070>
Call-ID: 1532307201
CSeq: 20 INVITE
Contact: <sip:client4@192.0.2.1:35011>
Content-Type: application/sdp
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY,
MESSAGE, SUBSCRIBE, INFO
Max-Forwards: 70
User-Agent: Linphone/3.4.0 (eXosip2/unknown)
Subject: Phone call
Content-Length: 538
v=0
o=client4 3867 3867 IN IP4 192.0.2.1
s=Talk
c=IN IP4 192.0.2.1
b=AS:256
t=0 0
m=audio 7056 RTP/AVP 111 110 3 101
a=altc:1 IP6 2001:db8:1f94:3000:6c73:ea54:cef:2730 45678
a=altc:2 IP4 192.0.2.1 7056
Figure 7: Content of the INVITE message (with ALTC Attribute)
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3.2. Avoid Crossing DS-Lite AFTR
SIP UAs co-located with the B4 [RFC6333] or located behind the CPE
can behave as dual-stack UAs:
o Native IPv6 address is assigned locally.
o The external IPv4 address and port is retrieved using PCP.
To avoid unnecessary invocation of AFTR resources, ALTC attribute is
used to signal both IPv4 and IPv6 addresses. If the remote SIP UA is
IPv6-enabled, IPv6 transfer capabilities will be used to place the
session (i.e., the flows will avoid crossing the DS-Lite AFTR
device). If the remote SIP UA is IPv4-only, IPv4 transfer
capabilities will be used. AFTR devices will be crossed only if the
remote UA is IPv4-only.
4. Security Considerations
PCP-related security considerations are discussed in [RFC6887].
Security considerations related to the discovery of PREFIX64 are
discussed in Section 7 of [RFC7225] and those related to retrieving a
set of ports are discussed in Section 7 of [I-D.ietf-pcp-port-set].
An attacker that wants to intercept media flows, without requiring
intercepting SIP signalling message, can insert a fake PCP server
that will influence the content of SIP messages so that an
illegitimate node is inserted in the media path. Such behavior is
not desirable. Means to prevent the PCP client from discovering
illegitimate PCP servers must be enforced. Within the context of
this document, the network on which the PCP messages are to be sent
is fully trusted. For example, access control lists (ACLs) can be
installed on the PCP client, PCP server, and the network between
them, so those ACLs allow only communications from a trusted PCP
client to the PCP server.
5. IANA Considerations
This document does not require any action from IANA.
6. Acknowledgements
Many thanks for T. Reddy and S. Kiesel for their review.
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7. References
7.1. Normative References
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>.
[RFC3581] Rosenberg, J. and H. Schulzrinne, "An Extension to the
Session Initiation Protocol (SIP) for Symmetric Response
Routing", RFC 3581, DOI 10.17487/RFC3581, August 2003,
<http://www.rfc-editor.org/info/rfc3581>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013,
<http://www.rfc-editor.org/info/rfc6887>.
7.2. Informative References
[I-D.boucadair-pcp-extensions]
Boucadair, M., Penno, R., and D. Wing, "Some Extensions to
Port Control Protocol (PCP)", draft-boucadair-pcp-
extensions-03 (work in progress), April 2012.
[I-D.boucadair-pcp-nat64-experiments]
Abdesselam, M., Boucadair, M., Hasnaoui, A., and J.
Queiroz, "PCP NAT64 Experiments", draft-boucadair-pcp-
nat64-experiments-00 (work in progress), September 2012.
[I-D.ietf-pcp-port-set]
Qiong, Q., Boucadair, M., Sivakumar, S., Zhou, C., Tsou,
T., and S. Perreault, "Port Control Protocol (PCP)
Extension for Port Set Allocation", draft-ietf-pcp-port-
set-13 (work in progress), October 2015.
[I-D.ietf-tsvwg-rtcweb-qos]
Dhesikan, S., Jennings, C., Druta, D., and P. Jones, "DSCP
and other packet markings for WebRTC QoS", draft-ietf-
tsvwg-rtcweb-qos-05 (work in progress), October 2015.
[I-D.penno-rtcweb-pcp]
Penno, R., Reddy, T., Wing, D., and M. Boucadair, "PCP
Considerations for WebRTC Usage", draft-penno-rtcweb-
pcp-00 (work in progress), May 2013.
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[ICEFailure]
Telemetry Dashboard, "WEBRTC_ICE_SUCCESS_RATE", March
2015, <http://telemetry.mozilla.org/#filter=beta%2F36%2FWE
BRTC_ICE_SUCCESS_RATE%2Fsaved_session%2FFirefox&aggregates
=multiselect-all!Submissions&evoOver=Builds&locked=true&sa
nitize=true&renderhistogram=Graph>.
[Power] Haverinen, H., Siren, J., and P. Eronen, "Energy
Consumption of Always-On Applications in WCDMA Networks",
April 2007, <http://ieeexplore.ieee.org/xpl/
articleDetails.jsp?arnumber=4212635>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>.
[RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
Stenberg, "UDP Encapsulation of IPsec ESP Packets",
RFC 3948, DOI 10.17487/RFC3948, January 2005,
<http://www.rfc-editor.org/info/rfc3948>.
[RFC4961] Wing, D., "Symmetric RTP / RTP Control Protocol (RTCP)",
BCP 131, RFC 4961, DOI 10.17487/RFC4961, July 2007,
<http://www.rfc-editor.org/info/rfc4961>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245,
DOI 10.17487/RFC5245, April 2010,
<http://www.rfc-editor.org/info/rfc5245>.
[RFC5626] Jennings, C., Ed., Mahy, R., Ed., and F. Audet, Ed.,
"Managing Client-Initiated Connections in the Session
Initiation Protocol (SIP)", RFC 5626,
DOI 10.17487/RFC5626, October 2009,
<http://www.rfc-editor.org/info/rfc5626>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010,
<http://www.rfc-editor.org/info/rfc6052>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>.
Boucadair & Parthasarathi Expires May 29, 2016 [Page 14]
Internet-Draft PCP & SIP November 2015
[RFC6223] Holmberg, C., "Indication of Support for Keep-Alive",
RFC 6223, DOI 10.17487/RFC6223, April 2011,
<http://www.rfc-editor.org/info/rfc6223>.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
<http://www.rfc-editor.org/info/rfc6333>.
[RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S.
Veikkolainen, "The Session Description Protocol (SDP)
Alternate Connectivity (ALTC) Attribute", RFC 6947,
DOI 10.17487/RFC6947, May 2013,
<http://www.rfc-editor.org/info/rfc6947>.
[RFC7118] Baz Castillo, I., Millan Villegas, J., and V. Pascual,
"The WebSocket Protocol as a Transport for the Session
Initiation Protocol (SIP)", RFC 7118,
DOI 10.17487/RFC7118, January 2014,
<http://www.rfc-editor.org/info/rfc7118>.
[RFC7220] Boucadair, M., Penno, R., and D. Wing, "Description Option
for the Port Control Protocol (PCP)", RFC 7220,
DOI 10.17487/RFC7220, May 2014,
<http://www.rfc-editor.org/info/rfc7220>.
[RFC7225] Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the
Port Control Protocol (PCP)", RFC 7225,
DOI 10.17487/RFC7225, May 2014,
<http://www.rfc-editor.org/info/rfc7225>.
[RFC7291] Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
the Port Control Protocol (PCP)", RFC 7291,
DOI 10.17487/RFC7291, July 2014,
<http://www.rfc-editor.org/info/rfc7291>.
[RFC7362] Ivov, E., Kaplan, H., and D. Wing, "Latching: Hosted NAT
Traversal (HNT) for Media in Real-Time Communication",
RFC 7362, DOI 10.17487/RFC7362, September 2014,
<http://www.rfc-editor.org/info/rfc7362>.
[WT-317] Broadband Forum, "Network Enhanced Residential Gateway
(NERG)", 2015, <https://www.broadband-forum.org/technical/
technicalwip.php>.
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Internet-Draft PCP & SIP November 2015
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Parthasarathi Ravindran
Nokia Networks
Manyata Embassy Business park
Bangalore, Karnataka 560045
India
Email: partha@parthasarathi.co.in
Boucadair & Parthasarathi Expires May 29, 2016 [Page 16]
