[SIPForum-discussion] Loose routing, strict routing

[Rajdeep Ahluwalia]

Hi Raghul,

The major difference in Strict-Routing and Loose-Routing is that in
strict routing the R-URI gets modified at each hop.

Steps done for strict routing proxy.
1. Push the R-URI at the end of route headers
2. Pop the topmost Route header and set it as the R-URI of the message

Following is an example msg flow in both cases
------------- Strict Routing ---------------------
UE1 -> P1
INVITE sip:rajdeep at aricent.com
Route sip:proxy1 at alcatel.com
Route sip:proxy2 at aricent.com
...
...

P1 -> P2
INVITE sip:proxy2 at aricent.com
Route sip:rajdeep at aricent.com
...
...

P2 -> UE2
INVITE sip:rajdeep at aricent.com
...
...

----------------- Loose Routing ----------------------
UE1 -> P1
INVITE sip:rajdeep at aricent.com
Route <sip:proxy1 at alcatel.com;lr>
Route <sip:proxy2 at aricent.com;lr>
...
...

P1 -> P2
INVITE sip:rajdeep at aricent.com
Route <sip:proxy2 at aricent.com;lr>
...
...

P2 -> UE2
INVITE sip:rajdeep at aricent.com
...
...

Hope this answers your query

Best regards,
Rajdeep



On 7/8/08, Raghul Prasanna <raghul82 at yahoo.co.uk> wrote:
> Hi All,
>
> Can anyone tell me the difference between Loose and Strict Routing please?
>
>   RFC 3261 says that a proxy is said to be loose routing if it follows the
> procedure stated in that doc...
>
>   Can somebody say what procedure the above definition means please?
>
> Also if the record route does not have lr parameter does it mean that if
> follows Strict routing?
>
> Please explain.
>
> Thanks,
> Raghul
>
>
>
>
>
>
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