[Freeswitch-users] Bypass media succeeds from extension to gateway but fails from extension to extension

[Phil Quesinberry]

Nevermind!  As it turns out, FS does send the correct external/NAT IP
addresses as long as BOTH extensions are set for bypass media.  Forgive me
for ever doubting...

Of course it still doesn't work for reasons discussed earlier, although I
think that it should work as long as there's no symmetric NAT involved.  I'm
guessing session border controller(s) will be the next step if we want to
remove the endpoint to endpoint traffic from our network.  Any suggestions?
OpenSIPS certainly looks promising.

Thanks,

- Phil

-----Original Message-----
From: Phil Quesinberry
Sent: Friday, May 11, 2012 2:41 PM
To: 'freeswitch-users at lists.freeswitch.org'
Subject: Bypass media succeeds from extension to gateway but fails from
extension to extension

Ken,

Thanks for taking the time to write that out.  I understand that and that
makes perfect sense, although the endpoints in this case are configured to
report their external IP addresses, either through STUN or a static NAT IP
entry.  What still is unclear to me is why this failed when FS was able to
successfully bridge the same extension directly to the PSTN gateway.

...
>From the traffic I pastebinned, we can see that Endpoint A is sending its
external WAN address info to FS, right before FS sends Endpoint A’s internal
LAN address to Endpoint B, so I would think that FS should be passing
Endpoint A’s WAN address along instead of its LAN address for media:
...

----------

Ken Rice
Thu May 10 19:08:53 MSD 2012 

The contact IP has nothing to do with where the media goes... That¹s
entirely defined in the SDP...

Consider this    Endpoint A (192.168.100.100) -> NAT A ->  FreeSWITCH
(4.2.2.2)  -> NAT B -> Endpoint B (192.168.100.200)

Now lets assume that NAT A and NAT B are 2 separate nat gateways and that
Endpoint A and Endpoint B are on 2 different physical LANs...   Telling
Endpoint A to talk directly to Endpoint B without proxying media will never
work since the endpoints think they are on the same LAN. There is no
mechanism there to allow for the redirection and automagic adjustments of
ports etc so that they can talk directly to each other...

Now lets change this slightly so that endpoint B is 192.168.200.200. Unless
NAT A knows how to get to 192.168.200.0/24 (assuming class C sized block)
and NAT B knows how to get to 192.168.100.0/24 they are both going to use
their default routing which is to NAT the outgoing RTP, and forward it to
the next hop...

Again, RTP will not make it to other side in either direction... FreeSWITCH
cant compensate due to a number of factors... Your Endpoints have to be
smart enough to actually compensate for the NAT in this situation OR your
NAT boxes have to compensate for it...

The simple answer, don¹t use bypass media in this situation, the complex
answer I wont get into here... Stop by IRC and ask around...

There is a 3rd option here you might want to consider, contact
consulting at freeswitch.org
<http://lists.freeswitch.org/mailman/listinfo/freeswitch-users>  for some
professional help... This may not be
specifially what you need to get going as I have no clue what your skill
level happens to be, and you did say you are still learning.

Good Luck!