[SIPForum-discussion] very imp question about route& recordroute

Sun Apr 29 08:00:31 UTC 2007

"now if p1 wants to be in media path then it will record route."  This is incorrect! Why P1 should add record route, if it want to be in media path? The speech path is only decided by SDP. If P1 want to be in media path, it can  be achieved by only modifing the address to itself in SDP.

  --sleepwalker

Deepanshu <deepanshu at huawei.com> 写道：
          Yes,  i think the confusion is caused by the following sentence of mine

    yes, i think so............... P1 is a default proxy for user A to forward his request.
  request will contain the route header, now if p1 wants to be in media path then it will record route

  i think that was a typo of something written in rush :-)

  offcourse, by adding record-route proxy is not leting itself in the media path but in the signalling path.

  Anyway the question raised by William was about route & record-route. which has been answered......

    Deepanshu Gautam
R&D Engineer
Huawei Technologies Co. Ltd.
Nanjing Institute, No 91 BaiXia Rd. 
Nanjing, Jiangsu, P. R. China 210001
Mobile: +86-13585147627
Email: depanshu at huawei.com

    ----- Original Message ----- 
  From: gurudatt balaji 
  To: Deepanshu 
  Cc: discussion at sipforum.org 
  Sent: Saturday, April 28, 2007 5:52 PM
  Subject: Re: [SIPForum-discussion] very imp question about route& recordroute

  Hi Deepanshu,

  Basically, the SIP signalling and the media do not traverse the same paths. 

  For instance in IMS, SIP signaling goes through the proxies (CSCF's), while the media goes via the GGSN or SBC or MGW (depending on the network) and proxies will not involved in processing media streams. (also not required) 

  By adding record_route header into the request, proxy ensures that subsequent requests (for ex re-Invite) flow through it onceagain, again it is SIP signalling not media.

  In simple terms media flows between two clients directly, and proxy is involved only in setting the session thro SIP signalling.

  Hope this clariffies your doubts.

  Reg
  Balaji

  On 4/28/07, Deepanshu <deepanshu at huawei.com> wrote:       I got it....

  But, can you give some reason to support your statement.

  When a proxy gets a request with route header and its a statefull proxy then it will insert a record_route header in the outgoing request. Due to that all the subsequent request will go through P1, which imply that P1 is in the media path. 

  on the other hand...

    When a proxy gets a request with route header and its a *stateless* proxy then it will *not* insert a record_route header in the outgoing request. Due to that all the subsequent request will *not* go through P1, which imply that P1 is *not* in the media path. 

  So, i cannot understand or support your statemt like "What i was saying is, P1 will not come into the media path". Why P1 will not come in media path? it depends on the procedures what proxy adopts. 

  hope i'm not missunderstanding you again

  Deepanshu Gautam
R&D Engineer
Huawei Technologies Co. Ltd.
Nanjing Institute, No 91 BaiXia Rd. 
Nanjing, Jiangsu, P. R. China 210001
Mobile: +86-13585147627
Email: depanshu at huawei.com

    ----- Original Message ----- 
  From: gurudatt balaji 
  To: Deepanshu 
  Sent: Friday, April 27, 2007 7:32 PM
  Subject: Re: [SIPForum-discussion] very imp question about route& recordroute

  ************************************************************************************************************************************
  yes, i think so............... P1 is a default proxy for user A to forward his request.

  request will contain the route header, now if p1 wants to be in media path then it will record route
  ************************************************************************************************************************************
  According to ur above statment,

  What i was saying is, P1 will not come into the media path"

  On 4/26/07, Deepanshu <deepanshu at huawei.com > wrote:       Sorry dear,

  i think i did not get you completely, are you trying to say that P1 cannot be in media path? (i hope not)
      ----- Original Message ----- 
  From: gurudatt balaji 
  To: Deepanshu 
  Cc: William Prusty ; discussion at sipforum.org 
  Sent: Wednesday, April 25, 2007 4:24 PM
  Subject: Re: [SIPForum-discussion] very imp question about route& recordroute

  Hi Deepanshu,

  I donot think P1 comes in the media path, also record_route header entries for subsequent requests (not media) within a dialog.

  Can u confirm.

  Reg
  Balaji

  On 4/25/07, Deepanshu <deepanshu at huawei.com > wrote:       yes, i think so............... P1 is a default proxy for user A to forward his request.

  request will contain the route header, now if p1 wants to be in media path then it will record route
    ----- Original Message ----- 
  From: William Prusty 
  To: Deepanshu 
  Sent: Tuesday, April 24, 2007 5:12 PM
  Subject: RE: [SIPForum-discussion] very imp question about route& recordroute

    If P1 must be configured at   A ;s client , then every time the request generated by A will contains the route header field containing the address of P1 

  Am I right?? Plz clarify

---------------------------------

  From: Deepanshu [mailto: deepanshu at huawei.com] 
Sent: Tuesday, April 24, 2007 2:34 PM 
To: William Prusty
Cc: discussion at sipforum.org
  Subject: Re: [SIPForum-discussion] very imp question about route& recordroute

    P1 MUST be configured in A's client

      ----- Original Message ----- 

    From: William Prusty 

    To: Deepanshu ; Srinivas . 

    Cc: discussion at sipforum.org 

    Sent: Tuesday, April 24, 2007 11:52 AM 

    Subject: RE: [SIPForum-discussion] very imp question about route& recordroute 

  Thank u deepansu. 

  If p1 is not configured in A "s client , then whether at that time A required help of DNS to find the address of p1.???? 

---------------------------------

  From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Deepanshu
Sent: Tuesday, April 24, 2007 7:23 AM
To: Srinivas .
Cc: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] very imp question about route& recordroute 

    My understanding about this is:

    P1 is the proxy server in A's domain, so the address of P1 should be configured in the A's client.

    when P1 receive the request it will do the DNS query to find the location of the next hop in the target domain (as per the line mentioned by Srinivas) and then send the request to P2 which will inturn forward the request to B 

    Deepanshu Gautam 
R&D Engineer
Huawei Technologies Co. Ltd.
Nanjing Institute, No 91 BaiXia Rd. 
Nanjing, Jiangsu, P. R. China 210001 
Mobile: +86-13585147627
Email: depanshu at huawei.com

      ----- Original Message ----- 

    From: Srinivas . 

    To: William Prusty ; mwilliam prusty ; discussion at sipforum.org 

    Sent: Monday, April 23, 2007 6:44 PM 

    Subject: Re: [SIPForum-discussion] very imp question about route & recordroute 

  William Refer RFC 3261 Section.10.

  If a user wants to initiate a
  session with another user, SIP must discover the current host(s) at
  which the destination user is reachable. This discovery process is
  frequently accomplished by SIP network elements such as proxy servers
  and redirect servers which are responsible for receiving a request,
  determining where to send it based on knowledge of the location of
  the user, and then sending it there.

---------------------------------

  From: William Prusty 
Sent: Monday, April 23, 2007 1:36 PM
To: Srinivas .; mwilliam prusty; discussion at sipforum.org
Subject: RE: [SIPForum-discussion] very imp question about route & recordroute

  Thank a lot srinivas. Plz make me clarify one thing more 

                  If A doesn't know IP address of p1 then how the invite request will reached at B 

---------------------------------

  From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Srinivas .
Sent: Monday, April 23, 2007 11:05 AM
To: mwilliam prusty; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] very imp question about route & recordroute

  William my comments inline

---------------------------------

  From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of mwilliam prusty
Sent: Saturday, April 21, 2007 10:20 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] very imp question about route & record route

can any body tell that 

suppose the call setup is lke  A  p1    p2    B

here A is user agent client. B is user agent  server. p1 & p2 are proxy. 
1.let A has generated an  INVITE request to B . in which case the invite request generated by A will conatin ROUTE header field.????
[Srinivas]  Generally , proxy P1 gets IP address of B from location server also if there are any proxies in between. 
                 Proxy P1 (generate INVITE) fills route and send  INVITE. 
  User A can fill route set only if it knows the proxies between user A and user B. 

2. let p1 has rcved the INVITE request containg ROUTE heder field.
is it mandatory that the invite from point p1 to p2 will conatin RECORD ROUTE heder field.????? if yes why if not why??? 
  [Srinivas] In some cases, it may be useful for proxies in the SIP signaling path to see all the messages pass between the endpoints for the session. In that case it will add RECORD ROUTE.  If it don't want to be in the path, it will not add the RECORD ROUTE. 

plz anser

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Disclaimer:

This message and the information contained herein is proprietary and confidential and subject to the Tech Mahindra policy statement, you may review at http://www.techmahindra.com/Disclaimer.html externally and http://tim.techmahindra.com/Disclaimer.html internally within Tech Mahindra.

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