Protocol Extensions for Header Compression over MPLS
RFC 4901
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RFC - Proposed Standard
(June 2007; No errata)
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Last updated |
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2015-10-14
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draft-ash-avt-hc-over-mpls-protocol
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IETF
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RFC 4901 (Proposed Standard)
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Responsible AD |
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Cullen Jennings
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pwe3-chairs@ietf.org, townsley@cisco.com
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Network Working Group J. Ash, Ed.
Request for Comments: 4901 J. Hand, Ed.
Category: Standards Track AT&T
A. Malis, Ed.
Verizon Communications
June 2007
Protocol Extensions for Header Compression over MPLS
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 IETF Trust (2007).
Abstract
This specification defines how to use Multi-Protocol Label Switching
(MPLS) to route Header-Compressed (HC) packets over an MPLS label
switched path. HC can significantly reduce packet-header overhead
and, in combination with MPLS, can also increases bandwidth
efficiency and processing scalability in terms of the maximum number
of simultaneous compressed flows that use HC at each router). Here
we define how MPLS pseudowires are used to transport the HC context
and control messages between the ingress and egress MPLS label
switching routers. This is defined for a specific set of existing HC
mechanisms that might be used, for example, to support voice over IP.
This specification also describes extension mechanisms to allow
support for future, as yet to be defined, HC protocols. In this
specification, each HC protocol operates independently over a single
pseudowire instance, very much as it would over a single point-to-
point link.
Ash, et al. Standards Track [Page 1]
RFC 4901 Header Compression over MPLS Protocol June 2007
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................3
3. Header Compression over MPLS Protocol Overview ..................6
4. Protocol Specifications ........................................11
4.1. MPLS Pseudowire Setup and Signaling .......................13
4.2. Header Compression Scheme Setup, Negotiation, and
Signaling .................................................14
4.2.1. Configuration Option Format [RFC3544] ..............15
4.2.2. RTP-Compression Suboption [RFC3544] ................17
4.2.3. Enhanced RTP-Compression Suboption [RFC3544] .......18
4.2.4. Negotiating Header Compression for Only TCP
or Only Non-TCP Packets [RFC3544] ..................19
4.2.5. Configuration Option Format [RFC3241] ..............20
4.2.6. PROFILES Suboption [RFC3241] .......................21
4.3. Encapsulation of Header Compressed Packets ................22
4.4. Packet Reordering .........................................23
5. HC Pseudowire Setup Example ....................................24
6. Security Considerations ........................................29
7. Acknowledgements ...............................................29
8. IANA Considerations ............................................29
9. Normative References ...........................................30
10. Informative References ........................................31
11. Contributors ..................................................33
Ash, et al. Standards Track [Page 2]
RFC 4901 Header Compression over MPLS Protocol June 2007
1. Introduction
Voice over IP (VoIP) typically uses the encapsulation
voice/RTP/UDP/IP. When MPLS labels [RFC3031] are added, this becomes
voice/RTP/UDP/IP/MPLS-labels. MPLS VPNs (e.g., [RFC4364]) use label
stacking, and in the simplest case of IPv4 the total packet header is
at least 48 bytes, while the voice payload is often no more than 30
bytes, for example. When IPv6 is used, the relative size of the
header in comparison to the payload is even greater. The interest in
header compression (HC) is to exploit the possibility of
significantly reducing the overhead through various compression
mechanisms, such as with enhanced compressed RTP (ECRTP) [RFC3545]
and robust header compression (ROHC) [RFC3095, RFC3095bis, RFC4815],
and also to increase scalability of HC. MPLS is used to route HC
packets over an MPLS label switched path (LSP) without
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