Internet DRAFT - draft-johansson-sip-he-connection
draft-johansson-sip-he-connection
SIPCORE O. Johansson
Internet-Draft Edvina AB
Intended status: Standards Track G. Salgueiro
Expires: April 24, 2017 Cisco Systems
D. Worley
Ariadne
October 21, 2016
Setting up a SIP (Session Initiation Protocol) connection in a dual
stack network using connection oriented transports
draft-johansson-sip-he-connection-01
Abstract
The Session Initiation Protocol (SIP) supports multiple transports
running both over IPv4 and IPv6 protocols. In more and more cases, a
SIP user agent (UA) is connected to multiple network interfaces. In
these cases setting up a connection from a dual stack client to a
dual stack server may suffer from the issues described in RFC 6555
[RFC6555] - Happy Eyeballs - significant delays in the process of
setting up a working flow to a server. This negatively affects user
experience.
This document builds on RFC 6555 and explains how a RFC3261 [RFC3261]
compliant SIP implementation can quickly set up working flows to a
given hostname (located by using DNS NAPTR and SRV lookups) in a dual
stack network using connection oriented transport protocols. A
solution for connectionless transport protocols is discussed in a
separate document.
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
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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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 24, 2017.
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Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Conventions Used in This Document . . . . . . 3
3. Background: DNS Procedures in a Dual-Stack Network . . . . . 4
4. Setting up the connection . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The core SIP [RFC3261] RFCs were written with support for both IPv4
and IPv6 in mind, but they were not fully equipped to handle highly
hybridized environments during this transitional phase of migration
from IPv4 to IPv6 networks, where many server and client
implementations run on dual stack hosts. In such environments, a
dual-stack host will likely suffer greater connection delay, and by
extension an inferior user experience, than an IPv4-only host. The
need to remedy this diminished performance of dual-stack hosts led to
the development of the Happy Eyeballs [RFC6555] algorithm, that has
since been implemented in many applications.
This document updates RFC 3261[RFC3261] procedures so that a dual-
stack client using connection oriented transport SHOULD set up
multiple connections in parallell, based on the result of DNS
queries. This document starts at the point where a SIP
implementation has a hostname that resolves in A and AAAA records.
This can either be part of a SIP URI including a port number or the
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result of a lookup using DNS NAPTR and SRV records as described in
RFC 3263[RFC3261], updated by RFC 7984[RFC7984]
Procedures for connectionless transport protocols for SIP will be
described in a separate document.
While this document use the term "dual-stack" based on RFC 6555 and
earlier terminology, the authors acknowledge that the same solution
can be applied to multi-interface environments as well as future
versions of IP alongside with the current ones.
2. Terminology and Conventions Used in This Document
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 RFC 2119 [RFC2119].
RFC 3261 [RFC3261] defines additional terms used in this document
that are specific to the SIP domain such as "proxy"; "registrar";
"redirect server"; "user agent server" or "UAS"; "user agent client"
or "UAC"; "back-to-back user agent" or "B2BUA"; "dialog";
"transaction"; "server transaction".
This document uses the term "SIP Server" that is defined to include
the following SIP entities: user agent server, registrar, redirect
server, a SIP proxy in the role of user agent server, and a B2BUA in
the role of a user agent server.
This document also uses the following terminology to make clear
distinction between SIP entities supporting only IPv4, only IPv6 or
supporting both IPv4 and IPv6.
IPv4-only UA/UAC/UAS: An IPv4-only UA/UAC/UAS supports SIP signaling
and media only on the IPv4 network. It does not understand IPv6
addresses.
IPv6-only UA/UAC/UAS: An IPv6-only UA/UAC/UAS supports SIP signaling
and media only on the IPv6 network. It does not understand IPv4
addresses.
IPv4/IPv6 UA/UAC/UAS: A UA/UAC/UAS that supports SIP signaling and
media on both IPv4 and IPv6 networks; such a UA/UAC/UAS is known
(and will be referred to in this document) as a "dual-stack"
[RFC4213] UA/UAC/UAS.
Discussion: Do we need special handling of websocket transport?
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3. Background: DNS Procedures in a Dual-Stack Network
SIP used DNS to find a server based on a SIP URI. This process is
described in RFC 3263[RFC3263] and updated in draft-ietf-sipcore-dns-
dual-stack. Using these procedures, a host name is selected and DNS
lookups of address records for all address families will generate a
list of IP addresses to connect to. This list will be used as input
for setting up a connection.
4. Setting up the connection
The Happy Eyeballs RFC [RFC6555] does not specify the algorithm used,
but requirements on algorithms used for quickly setting up a working
connection for the user. The reader is encouraged to read the
available documentation as well as study Open Source implementations
in order to learn from experience since the publishing of RFC 6555 in
2012.
In short, the SIP client is expected to set up two connections, with
some head start for one address family (which possibly should be
configurable) and then select the first working connection and close
the other one. The SIP message is sent on the selected connection
only.
The reason behind this is to avoid the timeout on one connection
before another address will be tested - which in the case of SIP with
default timers is 32 seconds. Waiting for timeout before trying with
a secondary address will lead to a very poor user experience.
5. Security Considerations
This document makes two normative changes to the existing procedures
in the SIP protocol. The specific security vulnerabilities, attacks
and threat models of the various protocols discussed in this document
(SIP, DNS, SRV records, etc.) are well documented in their respective
specifications.
6. IANA Considerations
This document does not require any actions by IANA.
7. Acknowledgements
The author would like to acknowledge the support and contribution of
the SIP Forum IPv6 Working Group. This document is based on a lot of
tests and discussions at SIPit events, organized by the SIP Forum.
Acknowledgements for reviews and input: Your name can be here!
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8. References
8.1. Normative References
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April
2012, <http://www.rfc-editor.org/info/rfc6555>.
8.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Protocol (SIP): Locating SIP Servers", RFC 3263,
DOI 10.17487/RFC3263, June 2002,
<http://www.rfc-editor.org/info/rfc3263>.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213,
DOI 10.17487/RFC4213, October 2005,
<http://www.rfc-editor.org/info/rfc4213>.
[RFC7984] Johansson, O., Salgueiro, G., Gurbani, V., and D. Worley,
Ed., "Locating Session Initiation Protocol (SIP) Servers
in a Dual-Stack IP Network", RFC 7984,
DOI 10.17487/RFC7984, September 2016,
<http://www.rfc-editor.org/info/rfc7984>.
Authors' Addresses
Olle E. Johansson
Edvina AB
Runbovaegen 10
Sollentuna SE-192 48
SE
Email: oej@edvina.net
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Gonzalo Salgueiro
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: gsalguei@cisco.com
Dale R. Worley
Ariadne Internet Services
738 Main St.
Waltham, MA 02451
US
Email: worley@ariadne.com
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