Subject: RE: [Tsvwg] Chunk and ParameterId Conflict

From: [email-masked]
Date: Thu, 21 Mar 2002 18:02:34 +0200

Hi Kashif!

	The point here is that the first two bits of the Chunk/Parameter Type field are also part of that Chunk/Parameter Type field... So, two chunks having the same last six bits in the Chunk Type field are not related in any way... They are simply different... There are not, let's say, "variations" in one Chunk Type. A Chunk Type can not change its first two bits to ask for a different answer from the peer (if it does not understand it), they are always set to the same value...

	Same with parameters...

	I hope this helps!

	BR Iván Arias Rodríguez

> -----Original Message-----
> From: ext Khan, Mohammad [mailto:[email-masked]]
> Sent: 21. March 2002 8:39
> To: [email-masked]'
> Subject: [Tsvwg] Chunk and ParameterId Conflict
> 
> 
> Hi All,
> In the draft for Dynamic Ip modification
> http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-addip-sct
> p-04.txt two
> new chunks have been introduced as ASCONF and ASCONF-ACK with 
> chunktypes as
> 0xc1 and 0x80 respectivily. As per the RFC 2960 first two 
> bits of the chunk
> types specify the action to be taken when the chunk type is 
> unspecified. So
> following confusion in the chunk Ids would be observed.
> 
> 	ChunkType	ChunkId		ChunkId with two MSBs
> Observation
> 	ASCONF	0xc1		
> 	INIT		0x01		0xc1(Both the MSBs Set)	
> It matches
> with ASCONF Chunk Type
> 	ASCONF-ACK	0x80
> 	DATA		0x00		0x80(One MSB set)	
> 	It
> matches with ASCONF-ACK Chunk Type
> 
> As per the SCTP Implementors Guide
> http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-sctpimpgu
> ide-03.txt
> 2.4.2 - e "Each parameter type must be unique across all 
> chunks". In the
> draft
> http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-addip-sct
> p-04.txt six
> new parameters have been added few of  which does not contain unique
> parameter types considering the existing parameter types with 
> two of the
> MSBs set to specify action when peer does not recognize it. 
> Following are
> the observation.
> 
> 	Parameter Type		ParameterId	ParameterId with twoMSBs
> Observation
> 	IPV4 Address		0x0005		0xC005(Both MSBs set)
> 	Success report		0xC005
> It matches with IPV4 address when two
> msbs are set
> 	IPV6 address		0x0006		0xC006(Both MSBs set)
> 	Adaptation Layer Indication 0xC006
> It matches with IPV6 address when two
> 	
> msbs are set
> 
> Please comment.
> 
> Regards
> kashif
> 	
> 	
> 
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> 

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