Subject: [BEHAVE] TCP framing in TURN

From: Evgeniy Khramtsov <[email-masked]>
Date: Wed, 18 Apr 2007 14:09:21 +1000

From draft-ietf-behave-turn-03.txt, para 5:

"The first octet of this framing is 0x02 to indicate STUN messages or 
0x03 to indicate end-to-end data to or from the active destination.  
Note that the first octet is always distinguishable from an unframed 
STUN request or response (which is always 0x00 or 0x01)."

Could you explain me why do you need to additionaly frame STUN messages 
since all STUN messages have always 0x00 or 0x01 in their first octet 
and we can simply distinguish them from the end-to-end data frame? Am I 
misreading something?

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From: Rémi Denis-Courmont <[email-masked]>
Date: Fri, 20 Apr 2007 12:49:50 +0300

> and we can simply distinguish them from the end-to-end data frame? Am I

Sure, we could avoid framing STUN messages (I vaguely remember this being 
already pointed out at the last meeting).

However, the end-to-end data framing will probably need to be changed to 
something that sets either or both of the higher-order two bits of the 
framing (since STUN always sets the first two bits to zero). Could be 
something like 0x4001PQRT then two bytes length, and then 0xPQRT bytes of TCP 
data.

-- 
Rémi Denis-Courmont

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From: "Mayank Dev Sondhi" <[email-masked]>
Date: Tue, 24 Apr 2007 21:52:31 +0530

In our implementation we use the below to differentiate framed vs. unframed
for backward compat. Makes me kinda wish for a versioning scheme in the
protocol as more folks adopt the draft standard.(unless we have one now,
haven't thoroughly checked the latest turn - 03)

-Mayank

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From: Evgeniy Khramtsov <[email-masked]>
Date: Wed, 25 Apr 2007 13:35:11 +1000

> haven't thoroughly checked the latest turn - 03)

I'm not quite sure what versioning scheme you are talking about. All 
'new' packets MUST have Magic Cookie in the header, thus you can 
differentiate them from 'old' packets.