[Freeswitch-users] Moving RTP relay to another FS BOX? (What's about REDIRECT)?

[Fabio Pietrosanti (naif)]

Another possible proposal to move RTP relay processing to another
FreeSWITCH could be as follow, please tell me if it sounds reasonable
(it sounds like a very dirty hack).
Consider that i just need to do RTP relay between 2 users (no
transcoding, no advanced features) on boxes differents from the FS
acting as SIP registration server.

FS-UK is in Europe.
FS-IN is in India.
C1 and C2 are in India.

C1 and C2 are connected to FS-UK in Europe for SIP.

I would like to have the flow as follow:
SIP Flow: C1 -> FS-UK -> C2
RTP flow: C1 -> FS-IN -> C2

A possible approach is to use the REDIRECT feature of FS.

FS-UK has bypass_media=true  & proxy_media=false
FS-IN has bypass_media=false & proxy_media=true

STEP1) C1 call C2 and FS-UK send a REDIRECT C2 at FS-IN

C1                             FS-UK

INVITE ------------------------------->
           <------------------------------ 100 Trying
           <------------------------------ 302 Moved Temporary C2 at FS2
ACK    ------------------------------->

<action application="redirect" data="sip:C2 at FS-IN"/>


STEP 2) C1 call C2 on C2 at FS-IN in India because of the redirect

C1                             FS-IN

INVITE C2 at FS-IN--------------------------------------------------------------------------------->

           <------------------------------ 100 Trying

STEP 3) FS-IN make a call back to C2 at FS-UK back to FS-UK

Now FS-IN make a bridge for C2 back on FS-UK (where C2 is SIP registered):

<action application="bridge" data="C2 at FS-UK"/>

FS-IN                             FS-UK

INVITE ------------------------------->
           <------------------------------ 100 Trying

STEP 4) FS-UK (which has bypass_media) let the C2 ring and answer the
call and provide the IP address of the leg on FS-IN

FS-UK                             C2

INVITE ------------------------------->
           <------------------------------ xxx ring, answer, etc

200 OK -------------------------------> For RTP it provide the IP address of FS-IN that has proxy_media=true


STEP 5) Now C1 and C2 are sending their RTP flow to FS-IN in india due to it's proxy_media SDP rewriting


I don't know if it was clear.

To summarize:

>From SIP point of view
C1 -> FS-UK (redirect) -> FS-IN (bridge back to FS-UK) -> FS-UK -> C2

>From RTP point of view
C1 -> FS-IN (proxy_media) -> C2

I just want to move certain users to their near media relay and install
one FS box for each continent so that my users will use the media-relay
near to them.

Does it seems feasible?

Fabio

On 30/12/10 12.00, Fabio Pietrosanti (naif) wrote:
> Hi Steven,
>
> if i understand correctly in your scenario "C2" is SIP registered to FS2.
>
> While i would like to have C1 and C2 both SIP registered to FS1, but if
> they match certain parameters (that's application logic), i want their
> RTP flow to goes proxed trough FS2.
>
> FS1 is in Europe.
> FS2 is in India.
> C1 and C2 are in India.
>
> C1 and C2 are connected to FS1 in Europe for SIP.
>
> I would like to have the flow as follow:
> SIP Flow: C1 -> FS1 -> C2
> RTP flow: C1 -> FS2 -> C2
>
> Obviously FS1 need in some way to be able to "instruct" C1 and C2 to go
> trough FS2, and FS2 to handle RTP relay.
>
> From my basic feeling i would need to move to a Kamailio+RTPProxy
> solutions, but if FS could have the flexibility to implement such
> solution it would be *much better* as i am already FS based.
>
> Also if some custom development is required, i would be happy to sponsor
> some bounty about it.
>
> Fabio

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