[nsp] Voip over NAT

ROY roy at cybees.com
Wed Jul 30 19:08:08 EDT 2003


This maybe off-list.

Has anyone ever made this work:
1. MCS 3.3 on public (x.x.200.4)
2. AS5400  on public (x.x.154.20)
3. Cisco 2600 doing 1:1 NAT for private to public
3. Cisco SoftPhone on PC#1 in a LAN (192.168.0.2 : x.x.3.2)
4. Cisco SoftPhone on PC#2 in a LAN (192.168.0.3 : x.x.3.3)

*Note: It has been verified that the softphones have registered with the
MCS using the public IPs [x.x.136.2 and x.x.136.3] using the network
audio settings.

I'm successful doing outbound calls. 

Local calls fail since packets do not pass through the router doing 1:1
NAT.

>From both PC#1 and PC#2 I can make outbound calls. Local call from PC#1
to PC#2 and vice-versa fails.

It was observed that packets from PC#1 do not reach PC#2 when
destination is the translated IP. i.e. from PC#1 to x.x.136.3 and from
PC#2 to x.x.136.2.

I can't ping x.x.136.2 from 192.168.0.3 and x.x.136.3 from 192.168.0.2.
Ping from public going towards both x.x.136.2 and x.x.136.3 is
successful though.

Have I missed something? Does someone have a similar implementation with
successful results?

TIA,
Roy




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