Session Description Protocol (SDP) Source Filters
RFC 4570
Document | Type | RFC - Proposed Standard (July 2006; Errata) | |
---|---|---|---|
Authors | Bob Quinn , Ross Finlayson | ||
Last updated | 2013-03-02 | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4570 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jon Peterson | ||
Send notices to | <jo@acm.org>, <csp@csperkins.org> |
Network Working Group B. Quinn Request for Comments: 4570 BoxnArrow.com Category: Standards Track R. Finlayson Live Networks, Inc. July 2006 Session Description Protocol (SDP) Source Filters Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document describes how to adapt the Session Description Protocol (SDP) to express one or more source addresses as a source filter for one or more destination "connection" addresses. It defines the syntax and semantics for an SDP "source-filter" attribute that may reference either IPv4 or IPv6 address(es) as either an inclusive or exclusive source list for either multicast or unicast destinations. In particular, an inclusive source-filter can be used to specify a Source-Specific Multicast (SSM) session. 1. Introduction The Session Description Protocol [SDP] provides a general purpose format for describing multimedia sessions in announcements or invitations. SDP uses an entirely textual data format (the US-ASCII subset of [UTF-8]) to maximize portability among transports. SDP does not define a protocol, but only the syntax to describe a multimedia session with sufficient information to discover and participate in that session. Session descriptions may be sent using any number of existing application protocols for transport (e.g., Session Announcement Protocol (SAP), SIP, Real Time Streaming Protocol (RTSP), email, and HTTP). Typically, session descriptions reference an IP multicast address for the "connection-address" (destination), though unicast addresses or fully qualified domain names (FQDNs) MAY also be used. The "source- Quinn, et al. Standards Track [Page 1] RFC 4570 SDP Source Filters July 2006 filter" attribute defined in this document qualifies the session traffic by identifying the address (or FQDN) of legitimate sources (senders). The intent is for receivers to use the source and destination address pair(s) to filter traffic, so that applications receive only legitimate session traffic. Receiver applications are expected to use the SDP source-filter information to identify traffic from legitimate senders, and discard traffic from illegitimate senders. Applications and hosts may also share the source-filter information with network elements (e.g., with routers using [IGMPv3]) so they can potentially perform the traffic filtering operation further "upstream," closer to the source(s). The "source-filter" attribute can appear at the session level and/or the media level. 1.1. Motivation The purpose of a source-filter is to help protect receivers from traffic sent from illegitimate source addresses. Filtering traffic can help to preserve content integrity and protect against Denial of Service (DoS) attacks. For multicast destination addresses, receiver applications MAY apply source-filters using the Multicast Source Filter APIs [MSF-API]. Hosts are likely to implement these APIs using protocol mechanisms to convey the source filters to local multicast routers. Other "upstream" multicast routers MAY apply the filters and thereby provide more explicit multicast group management and efficient utilization of network resources. The protocol mechanisms to enable these operations are beyond the scope of this document, but their potential provided motivation for SDP source-filters. 2. 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 RFC 2119 [REQMNT]. 3. The "source-filter" Attribute The SDP source-filter attribute does not change any existing SDP syntax or semantics, but defines a format for additional session description information. Specifically, source-filter syntax can prescribe one or more unicast addresses as either legitimate or illegitimate sources for any (or all) SDP session description "connection-address" field values. Quinn, et al. Standards Track [Page 2] RFC 4570 SDP Source Filters July 2006 Note that the unicast source addresses specified by this attributeShow full document text