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

The contact IP has nothing to do with where the media goes... That’s 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, don’t 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@freeswitch.org 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!

On 5/10/12 9:38 AM, "Phil Quesinberry" <philq@qsystemsengineering.com> wrote:

Thanks Ken. I’m still learning here, so if that’s the case then help me to understand why FS properly sends the external address when that same extension makes a call out through a gateway instead of to another extension. Same settings, same originating extension.

I did try enabling ndlb-connectile-dysfunction to rewrite the contact IP on those calls but to no avail.

Thanks!

- Phil

----------

Ken Rice
Tue May 8 11:38:48 MSD 2012

This is not a bug in FreeSWITCH...

Bypass Media is a special mode to allow us to act as a psuedo proxy.

Other then possibly filtering some codecs the rest of the SDPs are simply

copied across the bridge. That means if your sip devices are sending RFC1918

IPs in their SDPs then FreeSWITCH will forward an RFC1918 SDP. Why is that?

Because FreeSWITCH has no way to know where the media is actually coming

from since FreeSWITCH is not in the media path.

K

_____________________________________________
From: Phil Quesinberry

Sent: Monday, May 07, 2012 11:54 AM
To: 'freeswitch-users@lists.freeswitch.org'
Subject: Bypass media succeeds from extension to gateway but fails from extension to extension

I’m not sure if this is a bug or just a NAT-related configurational problem. If it’s truly a bug, let me know and I’ll be happy to file a Jira.

I’m trying to get bypass media to work with extension to extension calls. Both endpoint extensions are behind NAT in two different locations. This looks like a possible bug because FS sends the internal IP address of one of the endpoints to the other for media, but when making a call from the same extension to an external gateway for PSTN termination, it sends the phone’s external IP address as it should, and the call succeeds.

Everything works fine, of course, when “proxy media” is used.

The SIP traffic for the failed call is here, look for the word “WRONG!” to see the incorrect address being passed in the SDP:

http://pastebin.freeswitch.org/19003 <http://pastebin.freeswitch.org/19003>

Regards,

Phil Quesinberry

Q Systems Engineering, Inc.

Electronic Controls and Embedded Systems Development

(410) 969-8002

http://www.qsystemsengineering.com <http://www.qsystemsengineering.com>

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