[SIPForum-discussion] SIP using TCP or UDP?

[alexzhang at gdnt.com.cn]

Have you heard SCTP? It is a more reliable transportation protocol which has been used to tranport the SIP signalling. 


Thanks,
Alex Zhang 
G615/GD Nortel
6-554-8782(GZ)
6-444-1742(Rich)

-----Original Message-----
From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Rezaul Kabir
Sent: Sunday, January 14, 2007 2:16 AM
To: madan kumar
Cc: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] SIP using TCP or UDP?

I have not heard any such restrictions on the size of packet. But UDP is used by default and if you closely look at RTC 3261 Section
13.3.1.4 you will notice that it talks about a timer to retransmit packets and similar example is available in the rfc in several areas.
This behavior of retransmission clearly indicates that it is desirable to use non-reliable transport such as UDP to send the packets.
According to RFC3263 Section 4.1 is the Sip Uri does not specify any transport then UDP should be selected. Also by RFC2543 UDP is mandatory if no transport is defined and for good interpretability.
TCP should only be used if one is thinking of using SIPS/TLS OR the Sip Uri specifies TCP as transport.


----
Rezaul Kabir


On 1/13/07, madan kumar <mada2k at gmail.com> wrote:
> i far as i know udp is used when the packet size is less than 1200 
> bytes and TCP is used when it exceeds 1200 bytes ..... do any of u 
> have a explanation for this
>
>
> On 1/10/07, raman kumar <ramank24 at gmail.com> wrote:
> > when using the sip at the back-end use the UDP When using in the 
> > local premises use TCP
> >
> >
> >
> > On 26/12/06, Ramachandran <rgunasekaran at velankani.com> wrote:
> > > Dear all,
> > >
> > >
> > >
> > >  I am not very sure about the following,
> > >
> > >
> > >
> > > What is ideal transport protocol for SIP with IMS deployment?
> > >
> > > When to use SIP using UDP?
> > >
> > >
> > >
> > > Thanks,
> > >
> > > Ram
> > >
> > >
> > >
> > >
> > >
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