Skip to main content

Peer-to-Peer Session Initiation Protocol

Document Charter Peer-to-Peer Session Initiation Protocol WG (p2psip)
Title Peer-to-Peer Session Initiation Protocol
Last updated 2007-02-09
State Approved
WG State Concluded
IESG Responsible AD Alissa Cooper
Charter edit AD (None)
Send notices to (None)

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.