Subject: Re: [Sip] I-D: Preventing Fragmentation forClientInitiated Connections in the Session Initiation Protocol (SIP)

From: Marc Petit-Huguenin <[email-masked]>
Date: Fri, 16 Feb 2007 02:07:56 -0800

Michael Thomas wrote:
> Marc Petit-Huguenin wrote:
>> So there is 3 possible combinations of transports for SIP; UDP alone,
>> permanent TCP and UDP + temporary TCP.  I excluded UDP alone, because of
>> the fragmentation problem. So we wrote two tests with the same kind of
>> transactions an endpoints would do, the first test with a permanent TCP
>> connection, and the second test with a mix of UDP and temporary TCP.
>> The TCP/UDP mixed test, even if it have to create TCP connections and
>> close them each time a SIP message bigger than the MTU have to be sent
>> or received, was using half the resources of the test with the permanent
>> TCP connection.  And the UDP+TCP test was using the additional mechanism
>> to request the opening of the TCP connection.
>>   
> 
> Doesn't this all go down the drain when you add (D)TLS to the mix? The
> relative costs of establishment are orders of magnitude different right?
> (I wish I had that number off the top of my head, but I don't) That's
> really the thing that's swayed me with these debates since we shouldn't
> be counting on non-use of crypto going forward.
> 

I think that the solution is to use session resumption (and eventually
RFC 4507) between DTLS and TLS to reduce the cost of establishment.

I will add this to the next version the draft.

Thanks.

-- 
Marc Petit-Huguenin           [                                 ]
Home: [email-masked] [ RFC1855-compliant space for rent]
Work: [email-masked]            [                                 ]

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip