Hi All,

Following scenario might clear all the possible doubts....:)

Assume
proxy1 was STRICT router,
proxy2 was loose router,
proxy3 was loose-router,
proxy4 was STRICT router, this is what would happen -

scenario is : uac - p1 - p2 - p3 - p4 - uas

Route set for the transaction :
Route: <sip:proxy1.com>, <sip:proxy2.com;lr>,<sip:proxy3.com;lr>, <sip:
proxy4.com>

Remote party : sip:[email protected]

:: Request sent by UAC & received by Proxy1 :: (Loose --> Strict)
INVITE <sip:proxy1.com> sip/2.0
Route : <sip:proxy2.com;lr>,<sip:proxy3.com;lr>, <sip:proxy4.com>, <
sip:[email protected]>

:: Request sent by Proxy1 & received by Proxy2 :: (Strict --> Loose)
INVITE <sip:proxy2.com;lr> sip/2.0
Route : <sip:proxy3.com;lr>, <sip:proxy4.com>, <sip:[email protected]>

:: Request sent by Proxy2 & received by Proxy3 :: (Loose --> loose)
INVITE <sip:[email protected]> sip/2.0
Route : <sip:proxy3.com;lr>, <sip:proxy4.com>

:: Request sent by Proxy3 & received by Proxy4 :: (Loose --> STRICT)
INVITE <sip:proxy4.com> sip/2.0
Route : <sip:[email protected]>

:: Request sent by Proxy4 & received by UAS :: (STRICT --> loose/STRICT)
INVITE <sip:[email protected]> sip/2.0

Thanks,
Nataraju A B

On Thu, Nov 15, 2012 at 11:56 AM, Pranab Bohra <[email protected]>wrote:

> Hi,
>
> Few observations about proxy behaviour -
>
> 1. If the proxy is a strict-router, it just replaces the Request-URI with
> the top route-set element.
> 2. It the proxy is loose-router, it's behaviour depends on its adjacent
> proxy type, direction of message (upstream or downstream) and if it is
> responsible for the Request-URI resource.
> 3. If there's no strict-router in the path, Request-URI will not change
> and would always indicate the target of the request.
>
> For eg,
> If proxy1 was loose-router, proxy2 was strict, and prox3 was loose-router
> , this is what would happen -
>
>
> Route set = <sip:proxy2.com<http://proxy2.com/>>,<sip:proxy1.com<
> http://proxy1.com/>;lr>, <sip:proxy3.com;lr>
> Remote target = sip:[email protected]<mailto:sip%[email protected]>
>
> At UAS
> ======
> Request-URI = sip:proxy2.com<http://proxy2.com/>
> Route Header = <sip:proxy1.com<http://proxy1.com/>;lr>,<sip:proxy3.com;lr>,
> <sip:[email protected]<mailto:sip%[email protected]>>
>
> At proxy2
> =========
> Request-URI = sip:proxy1.com<http://proxy1.com/>;lr
> Route Header = <sip:proxy3.com;lr>,<sip:[email protected]<mailto:
> sip%[email protected]>>
>
> At proxy1
> ========
> proxy1 recognizes that the Request-URI it has received is the same that it
> had added to the Record-Route header while it was forwarding the request
> downstream. Its an indication that the previous proxy was strict.
> So it picks the URI from the bottom of the route-set and places it in
> Request-URI and forwards it to the next proxy.
>
> Request-URI = sip:[email protected]<mailto:[email protected]>
> Route Header = <sip:proxy3.com;lr>
>
>
> This behaviour is different from what Alok described.
>
> Thanks,
> Pranab
>
> ________________________________
> From: Alok 2 Tiwari [[email protected]]
> Sent: Thursday, November 15, 2012 11:07 AM
> To: Vivek Gupta; Pranab Bohra
> Cc: Vivek Batra; [email protected]
> Subject: RE: [Sip-implementors] What will be set in Request-URI with
> respect to loose and strict routing
>
> Hi Vivek,
>
> In the mentioned scenario, when request will reach at proxy2, proxy2 will
> do the following changes in SIP request before forwarding to remote:
>
>
> 1) Remove it’s own address from route set.
>
> 2) Remove the proxy1 address from Route header and set it into Request URI.
>
> 3) The remote address from Request URI will be set as strict router in
> Route header.
>
>
>
> Regards,
> Alok Tiwari
> Aricent
>
> From: Vivek Gupta [mailto:[email protected]]
> Sent: Thursday, November 15, 2012 10:41 AM
> To: Pranab Bohra
> Cc: Alok 2 Tiwari; Vivek Batra; [email protected]
> Subject: Re: [Sip-implementors] What will be set in Request-URI with
> respect to loose and strict routing
>
> Pranab,
>
> What would be the behavior if the route set is combination of strict and
> loose router? Considering the route set example as below:
>
> Route set = <sip:proxy2.com<http://proxy2.com/>;lr>,<sip:proxy1.com<
> http://proxy1.com/>>
> Remote target = sip:[email protected]<mailto:sip%[email protected]>
>
> >From UAC, I believe the outgoing request would have
> Request-URI = sip:[email protected]<mailto:sip%[email protected]>
> Route Header = <sip:proxy2.com<http://proxy2.com/>;lr>, <sip:proxy1.com<
> http://proxy1.com/>>
>
> However, when the request reaches 'proxy2' and its about to forward it to
> 'proxy1' then whether 'proxy2' be changing the request URI considering
> 'proxy1' is strict?
>
> With regards,
> Vivek Gupta
>
> On Wed, Nov 7, 2012 at 3:22 PM, Pranab Bohra <[email protected]
> <mailto:[email protected]>> wrote:
> Hi,
>
>
>
> The generic rule for in-dialog requests sent by UA is -
>
>                 Loose Router<--------- Top of route-set type ? -------->
> Strict router
>                     |
>     |
>                     |
>     |
>                     |
>     |
>                     V
>     V
>     ----------------------------------
>  -----------------------------------------------------------
>     | Request-URI = Remote Target URI|            |      Request-URI =
> First element of route-set           |
>     |                &&              |            |
>   &&                              |
>     |     route-set = As it is       |            | ( route-set = Rest of
> the route-set + Remote Target URI)|
>     ----------------------------------
>  -----------------------------------------------------------
>
>
> ===============================================================
>
> In 1st (loose router) case,
>
>
>
> route-set = <sip:proxy2.com<http://proxy2.com>;lr>,<sip:proxy1.com<
> http://proxy1.com>;lr>
>
> Remote target URI = sip:[email protected]<mailto:sip%[email protected]>
>
> So the outgoing request would have -
>
>
>
> Request- URI = sip:[email protected]<mailto:sip%[email protected]>
> Route Header = <sip:proxy2.com<http://proxy2.com>;lr>,<sip:proxy1.com<
> http://proxy1.com>;lr>
>
>
>
> ===============================================================
>
>
>
> In the 2nd (strict router) case,
>
>
>
> route-set = <sip:proxy2.com<http://proxy2.com>>,<sip:proxy1.com<
> http://proxy1.com>;lr>
>
> Remote target URI = sip:[email protected]<mailto:sip%[email protected]>
>
> So the outgoing request would have -
>
>
>
>
>
> Request- URI = sip:proxy2.com<http://proxy2.com>
>
> Route Header = <sip:proxy1.com<http://proxy1.com>;lr>,<sip:[email protected]
> <mailto:sip%[email protected]>>
>
>
>
> ===============================================================
>
>
>
>
>
> Thanks,
>
> Pranab
>
> ________________________________________
> From: [email protected]<mailto:
> [email protected]> [
> [email protected]<mailto:
> [email protected]>] On Behalf Of Alok 2
> Tiwari [[email protected]<mailto:[email protected]>]
> Sent: Wednesday, November 07, 2012 12:33 PM
> To: Vivek Batra; [email protected]<mailto:
> [email protected]>
> Subject: Re: [Sip-implementors] What will be set in Request-URI with
> respect to loose and strict routing
>
> Hi Vivek,
> In first case, request URI will be set as 'sip:[email protected]<mailto:
> sip%[email protected]>' and Route header will have 'sip:proxy2.com<
> http://proxy2.com>' as loose router.
> In second case, request URI will be set as 'sip:proxy2.com<
> http://proxy2.com>' and Route header will have 'sip:[email protected]<mailto:
> sip%[email protected]>' as strict router.
>
> Regards,
> Alok Tiwari
> Aricent
> -----Original Message-----
> From: [email protected]<mailto:
> [email protected]> [mailto:
> [email protected]<mailto:
> [email protected]>] On Behalf Of Vivek Batra
> Sent: Wednesday, November 07, 2012 11:55 AM
> To: [email protected]<mailto:
> [email protected]>
> Subject: [Sip-implementors] What will be set in Request-URI with respect
> to loose and strict routing
>
> Hi Folks,
>
> UA1 --> P1 --> P2 --> UA2
>
> 1. UA2 gets INVITE message as follows;
>
>  INVITE sip:[email protected]<mailto:sip%[email protected]>
>       Contact: sip:[email protected]<mailto:sip%[email protected]>
>       Record-Route: <sip:proxy2.com<http://proxy2.com>;lr>
>       Record-Route: <sip:proxy1.com<http://proxy1.com>;lr>
>
> Question is "When UA2 generates any message within dialog say BYE,
> Request-URI will be set to 'sip:[email protected]<mailto:sip%[email protected]>'
> or 'sip:proxy2.com<http://proxy2.com>'? This is a case where proxy2
> follows loose routing.
>
> 2. UA2 gets the INVITE message as follows;
>
>  INVITE sip:[email protected]<mailto:sip%[email protected]>
>       Contact: sip:[email protected]<mailto:sip%[email protected]>
>       Record-Route: <sip:proxy2.com<http://proxy2.com>>
>       Record-Route: <sip:proxy1.com<http://proxy1.com>;lr>
>
> Question is "When UA2 generates any message within dialog say BYE,
> Request-URI will be set to 'sip:[email protected]<mailto:sip%[email protected]>'
> or 'sip:proxy2.com<http://proxy2.com>'? This is a case where proxy2
> follows strict routing.
>
> Will appriecate your comments.
>
> Best Regards,
> Vivek Batra
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-- 
Thanks,
Nataraju A.B.
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