Sip passing through nat but rtp is not

patricianet · ‎07-14-2010

I'm looking at traffic leaving my router with a sniffer. I see SIP traffic but I do not see RTP traffic. The phones ring on both sides but I do not get any audio.

interface f0/0.100

ip address 192.168.10.1 255.255.255.0

ip nat outside

ip nat pool VoIP 192.168.10.1 192.168.10.1 prefix-length 24

ip nat inside source route-map VoIP pool VoIP overload
ip nat inside source static tcp 10.1.1.2 49201 192.168.10.54 49201 extendable

access-list 1 permit ip host 10.1.1.2 any

!
route-map VoIP permit 10
match ip address 1
match interface f0/0.100
set interface f0/0.100

Nagaraja Thanthry · ‎07-14-2010

Hello,

I guess you need to configure additional port maps for VoIP. Please check out this document:

http://www.cisco.com/en/US/docs/ios/ipaddr/configuration/guide/iad_pat_pt_rng.html

Hope this helps.

Regards,

NT

patricianet · ‎07-15-2010

Do I need to enable anything voip related for this to work?

Like voice service voip ?

Nagaraja Thanthry · ‎07-15-2010

Hello,

You can enable "ip nat service sip" or "ip nat service h323" and "ip nat

service h225" commands. As per the documentation, they are enabled by

default. In the latest IOS there is a new feature added to Cisco IOS that

ensures that even RTP packets get translated to one of the allowed ports as

specified by the RFC. The command to enable the feature is "ip nat service

allow-sip-even-rtp-ports"

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6640/pro

d_white_paper0900aecd80597bc7.html

Hope this helps.

Regards,

NT

patricianet · ‎07-15-2010

My IOS does not support the portmap command.

patricianet · ‎07-19-2010

Ok I configured the portmap command and I still do not get any audio.

This works with a linksys router but not with a cisco 2600 router

saif musa · ‎03-31-2015

Thanks Nagaraja Thanthry, that correct, I had the same issue and solved by using the instructions above ( ip nat service allow-sip-even-rtp-ports).

Regards