[asterisk-users] chan_sip sending from wrong source address when multiple interfaces are used

[Kevin P. Fleming]

On 07/11/2012 11:36 PM, Jeff LaCoursiere wrote:

> This does exhibit the problem though.  Your OS stack assumes one of
> those addresses - the first identified interface? - is the one that all
> replies will appear to come from.  So phones on the 192.168.2.0/24
> network that try to register get replies from 192.168.1.1 and ignore
> them.

No, I don't think it does. If the server has four interfaces, on subnets 
192.168.{1,2,3,4}.0/24, those are *not* overlapping, and everything will 
work as expected. If a UDP packet is received on the third interface, 
from an address reachable via routes over that interface, then the reply 
to that packet will be sent out over that same interface, with the 
source address set to the address assigned to that interface. Servers 
are setup this way all the time, and it works as it should.

There must be more to the network configuration than something this 
simple in order to cause the IP stack on the Asterisk server to choose 
the wrong source IP address for outbound packets.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
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