Subject: [rohc] Comment: draft-ietf-rohc-sigcomp-sip-05

From: "Tuukka Karvonen" <[email-masked]>
Date: Fri, 11 May 2007 11:31:10 +0300

We've encountered some SigComp interoperability problems between
different SIP stacks because of the following note in
draft-ietf-rohc-sigcomp-sip-05: 
"Note that some characters that are allowed to appear in a Via header
field parameter, such as ':' (colon), are not allowed to appear in a SIP
URI parameter, are not allowed to appear in a SIP URI parameter.  Those
characters need to be escaped when they appear in a SIP URI parameter." 

According to RFC 3261 ":" colon can be used without encoding in SIP URI
parameters and so some RFC 3261 compliant SIP stacks do not encode
colons in sigcomp-id automatically. Is there some other specifications
that demands the encoding of the colon character when it is used in a
SIP URI parameter? If not, it would good to use some other character as
an example e.g. '\' (backslash). 

RFC 3261:
> uri-parameters    =  *( ";" uri-parameter)
> uri-parameter     =  transport-param / user-param / method-param
>                      / ttl-param / maddr-param / lr-param /
other-param
> other-param       =  pname [ "=" pvalue ]
> pname             =  1*paramchar
> pvalue            =  1*paramchar
> paramchar         =  param-unreserved / unreserved / escaped
> param-unreserved  =  "[" / "]" / "/" / ":" / "&" / "+" / "$"

Best regards,

Tuukka Karvonen

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From: Gonzalo Camarillo <[email-masked]>
Date: Mon, 14 May 2007 13:54:42 +0300

Hi Tuukka,

yes, it seems SIP URI parameters can indeed contain colons. Thanks for 
pointing that out. I will remove that text from the draft and fix the 
examples so that they do not use escaping. I will submit a new revision 
of the draft shortly.

Cheers,

Gonzalo