[e2e] Fw: signaling performance on TCP

weigengyu weigengyu at hotmail.com
Sun Jun 4 20:55:45 PDT 2006

----- Original Message ----- 
From: "weigy" <weigy at aceway.com.cn>
To: "Randall Stewart" <randall at lakerest.net>; "Fred Baker" <fred at cisco.com>
Cc: <end2end-interest at postel.org>
Sent: Friday, June 02, 2006 1:02 PM
Subject: Re: [e2e] signaling performance on TCP

> Thank you for your replys. 
> And I would like to explain why I put the query.
> We make efforts on researching the performance of Signaling of IMS.
> From 3GPP and IETF, Sig of IMS would be transferred by SIP, 
> and SIP would be over TCP, UDP or SCTP.
> But, when we say signaling, most of people would like to compare it with SS7.
> As everybody knows, SS7 is lack of end to end transmission control,
> which has been the basis of TCP as end-to-end arguments.
> Although SCCP contains both connection and connectionless transmission, 
> most of the messages transfer use connectionless.
> For SS7,  we know that the traffic engineering in telecom based on Erlang formula even now. 
> The analysis model is M/M/n.
> The link capacity has been limited to 0.7 Erlang in engineering design and network operations. 
> From the preformance point of view, we know the limitation of each signaling link,
> we know the required delay limitation in each link and node (STP or SP), 
> So we have the signalling performance matrices. 
> The problem is  how the IMS signaling performace will be 
> when it is transfered by SIP, and SIP may be over TCP, UDP or SCTP. 
> The problem may be how the setup delay will be in such situation? 
> How the signaling would be affected by the difference when IMS sig in SIP over TCP, UDP or SCTP,
> and how to make it complied with the requirements of telecom.
> Is it adqate to put Sig/SIP/UDP, or Sig/SIP/TCP, or Sig/SIP/SCTP into use 
> at wireless link or core networks.   
> There are many differences between SS7 and Sig of IMS, 
> so, there are several problems that need to study.
> And we want to know if there are any related works, thoughts or publications.  
> Wei, Gengyu 
> The School of Computer Science & Technology
> Beijing University of Posts & Telecommunications 
> ----- Original Message ----- 
> From: "Randall Stewart" <randall at lakerest.net>
> To: "Fred Baker" <fred at cisco.com>
> Cc: "weigengyu" <weigengyu at hotmail.com>; <end2end-interest at postel.org>
> Sent: Thursday, June 01, 2006 11:31 PM
> Subject: Re: [e2e] signaling performance on TCP
>> Fred:
>> In principle I agree.. with on cavet..
>> Most TCP stacks today require a blocking connect()
>> so you get
>> -----SYN---->
>> <----SYN-ACK---
>> -----ACK---->
>> unblock
>> ----First-Data---->
>> <----ACK +....
>> This is true for SCTP if you use the socket api one-2-one model
>> but NOT true for SCTPif you use the socket api one-2-many model.. you
>> get
>> ----INIT---->
>> <---INIT-ACK---
>> ---COOKIE+DATA--->
>>  <---DATA
>> That all being siad this is only a slight advantage and
>> probably just a small bit..
>> The only place that SCTP makes a lot more sense for SIP is
>> between SIP proxy's.. in that case we can have one
>> connection and route calls over different streams to
>> avoid HOL Blocking...  But I don't think that is what
>> the query was about :-D
>> R
>> Fred Baker wrote:
>>> I don't see why SCTP would fare one iota different than TCP. In context, 
>>> they have essentially equivalent message exchange. SIP on UDP would do 
>>> it in less RTTs, in that there would be no SYN/SYN-ACK or FIN/FIN-ACK. I 
>>> think the real difference there is debateable, though.
>>> Allocating excess capacity to a signaling channel and putting SIP into 
>>> it basically allows SIP to bypass queues that form around file 
>>> transfers. Personally, I think this is a good thing, and RFC 4542 
>>> supports it.
>>> On May 15, 2006, at 11:13 PM, weigengyu wrote:
>>>> Hi,
>>>> Can anyone give an answer to my question?
>>>> 1. SIP will be the signaling protocol for IMS in 3GPP,and SIP can be 
>>>> over TCP, UDP, or SCTP;
>>>> 2. For SIP over TCP as signaling transfer, are there any analysis 
>>>> model for the performance evaluation?
>>>> 3. Somebody told me that there is no problem if you allocate enough 
>>>> bandwidth to signaling channel.
>>>>    (the enough bandwidth in engineering design may be 10% of total 
>>>> transmission line capacity) 
>>>>    So, is there any measured data to support the above design.
>>>> 4. Could you get better performance by SIP over SCTP than SIP over TCP 
>>>> for signaling transfer?
>>>> Gengyu
>> -- 
>> Randall Stewart
>> 803-345-0369 <or> 815-342-5222(cell)

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