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Concluded WG Peer-to-Peer Session Initiation Protocol (p2psip)

Note: The data for concluded WGs is occasionally incorrect.

WG Name Peer-to-Peer Session Initiation Protocol
Acronym p2psip
Area Applications and Real-Time Area (art)
State Concluded
Charter charter-ietf-p2psip-03 Approved
Document dependencies
Additional resources Issue tracker, Wiki
Personnel Chairs Brian Rosen, Carlos J. Bernardos
Area Director Alissa Cooper
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Final Charter for Working Group

The Peer-to-Peer (P2P) Session Initiation Protocol working group
(P2PSIP WG) is chartered to develop protocols and mechanisms for the
use of the Session Initiation Protocol (SIP) in settings where the
service of establishing and managing sessions is principally handled
by a collection of intelligent endpoints, rather than centralized
servers as in SIP as currently deployed. A number of cases where such
an architecture is desirable have been documented.

The work focuses on collections of nodes called "P2PSIP peers" and
"P2PSIP clients". P2PSIP peers manifest a distributed namespace in
which overlay users are identified and provides mechanisms for
locating users or resources within the P2PSIP overlay. P2PSIP clients
differ from P2PSIP peers primarily in that they do not store
information in the overlay, but only use it to locate users and
resources. P2PSIP clients and peers use the resolution services of the
peers as an alternative to the SIP discovery process of RFC 3263. In
this way, P2PSIP offers an alternative mechanism for determining the
correct destination for SIP requests. The working group's initial
charter scope will be to produce protocols to enable this alternate
mechanism for RFC 3263 functionality. Session management, messaging,
and presence functions are performed using conventional SIP.

This group's primary tasks are to produce:

  1. An overview document explaining concepts, terminology, rationale,
    and illustrative use cases for the remaining work.

  2. A proposed standard defining a P2PSIP Peer Protocol. This protocol
    is used between P2PSIP overlay peers, some of which may be behind
    NATs. This protocol will define how the P2PSIP peers collectively
    provide for user and resource location in a SIP environment with no or
    minimal centralized servers. This protocol may or may not be
    syntactically based on SIP, a decision to be made by the WG. The group
    will identify and require one base P2P algorithm (likely a particular
    Distributed Hash Table (DHT) algorithm), while allowing for additional
    optional algorithms in the future.

  3. Optionally, a proposed standard defining a P2PSIP Client Protocol
    for use by P2PSIP clients, some of which may be behind NATs. This
    protocol will define how the P2PSIP clients query and/or modify, the
    resource location information of the overlay. While clearly a logical
    subset of the P2PSIP Protocol, the WG will determine if the P2PSIP
    Client Protocol is a syntactic subset of the P2PSIP Peer Protocol, and
    whether the P2PSIP Client Protocol builds on the SIP protocol.

  4. A usage document. This document will address how the protocols
    defined above, along with existing IETF protocols, can be used to
    produce systems to locate a P2PSIP peer or client, identify appropriate
    resources to facilitate communications (for example media relays), and
    establish communications between the users of these P2PSIP peers or
    clients, without relying on centralized servers. Additionally, the
    document will explain how P2PSIP and conventional SIP entities can

The initial work will assume the existence of some enrollment process
that provides a unique user name, credentials, and an initial set of
bootstrap nodes if that is required by the protocols. Developing a
non-centralized enrollment process is not in scope.

The work planned for the P2PSIP working group is distinct from, but
requires close participation with other IETF WGs, particularly SIP,
SIPPING, SIMPLE, BEHAVE and MMUSIC. The group cannot modify the
baseline SIP behavior, define a new version of SIP, or attempt to
produce a parallel protocol for session establishment. If the group
determines that any capabilities requiring an extension to SIP are
needed, the group will seek to define such extensions within the SIP
working group using the SIP change process (RFC 3427). Similarly,
existing tools developed in the BEHAVE and MMUSIC groups will be used
for NAT traversal, with extensions or changes desired to support P2PSIP
presented to the BEHAVE or MMUSIC working groups.

The working group will assume that NATs and firewalls exist in the
Internet, and will ensure that the protocols produced work in their
presence as much as possible. Similarly, the WG will avoid making
protocol design decisions that would preclude the creation of anonymous
communications systems using techniques such as onion routing to
conceal the IP addresses of P2PSIP peers.

P2P networks pose unique security and privacy problems because an
adversarial relationship may exist between nodes. Attackers can mount
both integrity attacks on the stored data and denial of service
attacks on the system as a whole. The WG will not attempt a solution
to these issues for P2P networks in general. In order to simplify this
problem, the WG will assume that all participants in the system are
issued unique identities and credentials through some mechanism not in
the scope of this working group, such as a centralized server, and
that the data stored in the network will be authenticated by the
storing entity in order to address the integrity issue and to some
extent alleviate the DoS issue. Because signaling dialogs may be
routed through intermediate P2PSIP peers which may be untrusted by the
originating SIP UA, the WG will address the issue of establishing
authenticated signaling dialogs through such untrusted relays.

P2P systems also have privacy issues because the nodes that store data
objects and route requests are unrelated to the clients which want to
communicate. In the design of the P2PSIP protocol, the WG will assess
these privacy issues and determine to what extent they need to be
alleviated. The protocol document will contain a complete description
of the privacy properties of P2PSIP.

The following topics are excluded from the Working Group's scope:

  1. Issues specific to applications other than locating users and
    resources for SIP-based communications and presence.

  2. Solving "research" type questions related to P2PSIP or P2P in
    general. The WG will instead forward such work to the IRTF P2PRG or
    other RG as appropriate. Examples include fully distributed schemes for
    assuring unique user identities and the development of P2P-based
    replacements for DNS.

  3. Locating resources based on something other than URIs. In other
    words, arbitrary search of attributes is out of scope, but locating
    resources based on their URIs is in scope. Using URIs need not imply
    using the DNS or having a record in the DNS for the URI.

  4. Multicast and dynamic DNS based approaches as the core lookup
    mechanism for locating users and resources. Approaches based on these
    technologies may be reasonable ways to solve similar problems but that
    is not the focus of this WG. These techniques may be in-scope for
    locating bootstrap peers/servers or for interoperation with
    conventional SIP.


Date Milestone Associated documents
Oct 2013 Submit P2PSIP Concepts document to the IESG (Informational)
Oct 2013 Submit P2PSIP SIP Usage document to the IESG (PS)
Jul 2013 Submit P2PSIP Service Discovery document to the IESG (PS)
Jul 2013 Submit P2PSIP Self-Tuning document to the IESG (PS)
Jul 2013 WGLC of P2PSIP SIP Usage document
Jul 2013 WGLC of P2PSIP Concepts document
Jul 2013 Submit P2PSIP Diagnostics document to the IESG (PS)
Feb 2013 Submit P2PSIP Peer Protocol document to the IESG (PS)
Feb 2013 WGLC of P2PSIP Self-Tuning document
Feb 2013 WGLC of P2PSIP Service Discovery document
Feb 2013 Submit -00 draft on Configuration of Access Control Policy in RELOAD

Done milestones

Date Milestone Associated documents
Done WGLC of P2PSIP Relay Response Draft
Done WGLC of P2PSIP Direct Response Draft
Done WGLC of P2PSIP Diagnostics document
Done WGLC of P2PSIP Peer Protocol document