< draft-ietf-rohc-ip-only-03.txt		draft-ietf-rohc-ip-only-04.txt >
	Network Working Group Lars-Erik Jonsson, Ericsson		Network Working Group Lars-Erik Jonsson, Ericsson
	INTERNET-DRAFT Ghyslain Pelletier, Ericsson		INTERNET-DRAFT Ghyslain Pelletier, Ericsson
	Expires: March 2004		Expires: March 2004
	September 12, 2003		September 25, 2003
	RObust Header Compression (ROHC):		RObust Header Compression (ROHC):
	A Compression Profile for IP		A Compression Profile for IP
	<draft-ietf-rohc-ip-only-03.txt>		<draft-ietf-rohc-ip-only-04.txt>
	Status of this memo		Status of this memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that other		Task Force (IETF), its areas, and its working groups. Note that other
	groups may also distribute working documents as Internet-Drafts.		groups may also distribute working documents as Internet-Drafts.
	skipping to change at page 2, line 16 ¶		skipping to change at page 2, line 16 ¶
	1. Introduction..................................................2		1. Introduction..................................................2
	2. Terminology...................................................3		2. Terminology...................................................3
	3. ROHC IP Compression (Profile 0x0004)..........................3		3. ROHC IP Compression (Profile 0x0004)..........................3
	3.1. Static chain termination...............................3		3.1. Static chain termination...............................3
	3.2. Handling multiple levels of IP headers.................3		3.2. Handling multiple levels of IP headers.................3
	3.3. Constant IP-ID.........................................4		3.3. Constant IP-ID.........................................4
	3.4. Additional mode transition logic.......................6		3.4. Additional mode transition logic.......................6
	3.5. Initialization.........................................7		3.5. Initialization.........................................7
	3.6. Packet types...........................................8		3.6. Packet types...........................................8
			3.7. The CONTEXT_MEMORY feedback option.....................9
	4. Security Considerations.......................................9		4. Security Considerations.......................................9
	5. IANA Considerations...........................................9		5. IANA Considerations...........................................9
	6. Intellectual Property Right Claim Considerations..............9		6. Intellectual Property Right Claim Considerations.............10
	7. Acknowledgements.............................................10		7. Acknowledgements.............................................10
	8. References...................................................10		8. References...................................................10
	9. Authors' Addresses...........................................10		9. Authors' Addresses...........................................11
	Appendix A. Detailed procedures for canceling mode transitions..11		Appendix A. Detailed procedures for canceling mode transitions..12
	A.1. Transition from Optimistic to Reliable mode................11		A.1. Transition from Optimistic to Reliable mode................12
	A.2. Transition from Unidirectional to Reliable mode............12		A.2. Transition from Unidirectional to Reliable mode............13
	A.3. Transition from Reliable to Optimistic mode................12		A.3. Transition from Reliable to Optimistic mode................13
	A.4. Transition back to Unidirectional mode.....................13		A.4. Transition back to Unidirectional mode.....................14
	1. Introduction		1. Introduction
	The original RObust Header Compression (ROHC) RFC [RFC-3095] defines		The original RObust Header Compression (ROHC) RFC [RFC-3095] defines
	a framework for header compression, along with compression protocols		a framework for header compression, along with compression protocols
	(profiles) for IP/UDP/RTP, IP/ESP, IP/UDP, and also a profile for		(profiles) for IP/UDP/RTP, IP/ESP, IP/UDP, and also a profile for
	uncompressed packet streams. The profile for uncompressed data was		uncompressed packet streams. The profile for uncompressed data was
	defined to provide means to encapsulate all traffic over a link		defined to provide means to encapsulate all traffic over a link
	within ROHC packets. Through this profile, the lower layers do not		within ROHC packets. Through this profile, the lower layers do not
	have to provide multiplexing for different packet types, but instead		have to provide multiplexing for different packet types, but instead
	skipping to change at page 6, line 22 ¶		skipping to change at page 6, line 22 ¶
	For the IP profile defined in this document, the Mode parameter for		For the IP profile defined in this document, the Mode parameter for
	the value mode = 0 (packet types UOR-2, IR and IR-DYN) is redefined		the value mode = 0 (packet types UOR-2, IR and IR-DYN) is redefined
	to allow the compressor to decline a mode transition requested by the		to allow the compressor to decline a mode transition requested by the
	decompressor:		decompressor:
	Mode: Compression mode. 0 = (C)ancel Mode Transition		Mode: Compression mode. 0 = (C)ancel Mode Transition
	Upon receiving the Mode parameter set to '0', the decompressor MUST		Upon receiving the Mode parameter set to '0', the decompressor MUST
	stay in its current mode of operation and SHOULD refrain from sending		stay in its current mode of operation and SHOULD refrain from sending
	further mode transition requests for a certain amount of time.		further mode transition requests for the declined mode for a certain
			amount of time.
	More specifically, with reference to the parameters C_TRANS, C_MODE,		More specifically, with reference to the parameters C_TRANS, C_MODE,
	D_TRANS and D_MODE defined in [ROHC, section 5.6.1.], the following		D_TRANS and D_MODE defined in [ROHC, section 5.6.1.], the following
	modifications apply when the compressor cancels a mode transition:		modifications apply when the compressor cancels a mode transition:
	Parameters for the compressor side:		Parameters for the compressor side:
	- C_MODE:		- C_MODE:
	This value must not be changed when sending mode information		This value must not be changed when sending mode information
	within packets when the mode parameter set to '0' (as a		within packets when the mode parameter set to '0' (as a
	skipping to change at page 8, line 7 ¶		skipping to change at page 8, line 7 ¶
	For ROHC IP, the dynamic part of an IR or IR-DYN packet is similar to		For ROHC IP, the dynamic part of an IR or IR-DYN packet is similar to
	the one for ROHC UDP, with a two-octet field containing the SN		the one for ROHC UDP, with a two-octet field containing the SN
	present at the end of the dynamic chain in IR and IR-DYN packets. It		present at the end of the dynamic chain in IR and IR-DYN packets. It
	should be noted that the static and dynamic chains have an arbitrary		should be noted that the static and dynamic chains have an arbitrary
	length, and the SN is added only once, at the end of the dynamic		length, and the SN is added only once, at the end of the dynamic
	chain in IR and IR-DYN packets.		chain in IR and IR-DYN packets.
	3.6. Packet types		3.6. Packet types
	The only packet format that differs from ROHC UDP is the general		Except for one new feedback option (see section 3.7), the only packet
	format for compressed packets, which has no UDP checksum in the end.		format that differs from ROHC UDP is the general format for
	Instead, it ends with a list of dynamic header portions, one for each		compressed packets, which has no UDP checksum in the end. Instead, it
	IP header above the initial two (if any, as indicated by the presence		ends with a list of dynamic header portions, one for each IP header
	of corresponding header portions in the static chain).		above the initial two (if any, as indicated by the presence of
			corresponding header portions in the static chain).
	The general format for a compressed header is thus as follows:		The general format for a compressed header is thus as follows:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	--- --- --- --- --- --- --- ---		--- --- --- --- --- --- --- ---
	: Add-CID octet : |		: Add-CID octet : |
	+---+---+---+---+---+---+---+---+ |		+---+---+---+---+---+---+---+---+ |
	| first octet of base header | |		| first octet of base header | |
	+---+---+---+---+---+---+---+---+ |		+---+---+---+---+---+---+---+---+ |
	: : |		: : |
	skipping to change at page 9, line 9 ¶		skipping to change at page 9, line 9 ¶
	--- --- --- --- --- --- --- ---		--- --- --- --- --- --- --- ---
	: List of :		: List of :
	/ Dynamic chains / variable, given by static chain		/ Dynamic chains / variable, given by static chain
	: for additional IP headers : (includes no SN)		: for additional IP headers : (includes no SN)
	--- --- --- --- --- --- --- ---		--- --- --- --- --- --- --- ---
	Note that the list of dynamic chains for the additional IP headers in		Note that the list of dynamic chains for the additional IP headers in
	compressed packets do not have a sequence number at the end of the		compressed packets do not have a sequence number at the end of the
	chain, as SN is present within compressed base headers.		chain, as SN is present within compressed base headers.
			3.7. The CONTEXT_MEMORY feedback option
			The CONTEXT_MEMORY option informs the compressor that the
			decompressor does not have sufficient memory resources to handle the
			context of the packet stream, as the stream is currently compressed.
			0 1 2 3 4 5 6 7
			+---+---+---+---+---+---+---+---+
			| Opt Type = 9 | Opt Len = 0 |
			+---+---+---+---+---+---+---+---+
			When receiving a CONTEXT_MEMORY option, the compressor should take
			actions to compress the packet stream in a way that requires less
			decompressor memory resources, or stop compressing the packet stream.
	4. Security Considerations		4. Security Considerations
	The security considerations of [RFC-3095] apply equally to this		The security considerations of [RFC-3095] apply equally to this
	document, without exceptions or additions.		document, without exceptions or additions.
	5. IANA Considerations		5. IANA Considerations
	ROHC profile identifier 0x0004 has been reserved by the IANA for the		ROHC profile identifier 0x0004 has been reserved by the IANA for the
	profile defined in this document.		profile defined in this document.
	skipping to change at page 14, line 33 ¶		skipping to change at page 15, line 33 ¶
	The limited permissions granted above are perpetual and will not be		The limited permissions granted above are perpetual and will not be
	revoked by the Internet Society or its successors or assigns.		revoked by the Internet Society or its successors or assigns.
	This document and the information contained herein is provided on an		This document and the information contained herein is provided on an
	"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING		"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
	TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING		TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
	BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION		BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
	HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF		HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
	MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.		MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	This Internet-Draft expires March 12, 2004.		This Internet-Draft expires March 25, 2004.
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