[MMUSIC] RE: Question on draft-ietf-mmusic-kmgmt-ext-15

Hello!

A Crypto session is equivalent to an SRTP session 
when using the SRTP profile in MIKEY (see Appendix 
A of RFC 3830).  Hence, no other media than SAVP (in your example) can 
be regarded as a Crypto Session.  So for your examples below, 
4 is the answer (only SAVP counts).

Regards,
Karl

> -----Original Message-----
> From: Elwell, John [mailto:john.elwell@siemens.com]
> Sent: den 20 oktober 2005 15:49
> To: Jari Arkko (JO/LMF); elisabetta.carrara@ericsson.com; Fredrik
> Lindholm (AL/EAB); Mats Näslund (KI/EAB); Karl Norrman (KI/EAB)
> Cc: mmusic@ietf.org; Fries, Steffen
> Subject: Question on draft-ietf-mmusic-kmgmt-ext-15
> 
> 
> In section 7.1, first bullet it states:
> "When referring to streams described in SDP, MIKEY SHALL allocate two
> consecutive numbers for the related Crypto Session indexes 
> (as each stream
> can be bi-directional). An example: if the SDP contains two m lines
> (specifying whatever direction of the streams), and MIKEY is 
> at the session
> level, then MIKEY allocates e.g. the Crypto Sessions 
> Identifiers (CS IDs,
> see [MIKEY)] '1' and '2' for the first m line, and '3' and '4' for the
> second m line."
> My question is, what if not all m= lines use SRTP transport, 
> e.g., some use
> RTP transport? Must MIKEY still allocate Crypto Sessions for 
> each m= line,
> even though there is no way of indicating anything other than 
> "SRTP" as the
> protocol type in the security profile of a Crypto Session? Or does the
> statement quoted above apply only to media that require a 
> security profile?
> 
> Consider this example:
> m=xxxx ppp RTP/SAVP
> m=xxxx ppp RTP/AVP
> m=xxxx ppp RTP/SAVP
> Must I allocate 6 Crypto Sessions (2 for each m= line) for 
> this, i.e, CS ID
> 1 and 2 to the first, CS ID 3 and 4 to the second, etc.? If 
> so, what goes in
> the protocol type of the security profile for the CS ID 3 and CS ID 4
> entries in the CS ID map?
> Or can I allocate just 4 Crypto Sessions, which implicitly 
> would apply to
> the first and last m= lines?
> 
> Consider also this example:
> m=xxxx ppp RTP/SAVP
> m=xxxx ppp RTP/SAVP
> m=xxxx ppp RTP/AVP
> A similar question, although note here that the SRTP media 
> are contiguous,
> so if I only allocate 4 Crypto Session, then they would map 
> to the first and
> second m= lines (i.e., no gap). Would this be preferable, or 
> do I still need
> to allocate 6?
> 
> John
> 

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