NAT-PAT port range for VoIP

Unanswered Question
Apr 17th, 2007
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I'm trying to set a nat translation from outside to inside for a udp range port.

I've try some configurations. Here is the last one:

ip nat inside source route-map RTP interface Dialer0 [reversible] overload

access-list 110 remark Nat Host RTP

access-list 110 permit udp host range 10001 20000 any

route-map RTP permit 10

match ip address 110

I've got an Dynamic IP from my provider. The internal range is

Why this doesn't work?

Some advices?

Thanks in advance

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Overall Rating: 2 (1 ratings)
dgahm Tue, 04/17/2007 - 07:09
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Cisco VOIP uses a RTP UDP port range of 16384 to 32767, so your port range is one possibility. Do you have ip nat inside and outside statements on the interfaces? Have you tried a debug ip nat?

Please rate helpful posts.


olafmarcos Tue, 04/17/2007 - 07:21
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Hi Dave:

Yes. I have ip nat inside and outside statements on interfaces. The range is for Asterisk standard RTP port range, so I don't use the cisco voip range. I use cisco 857 with ios Version 12.4(6)T6.

I don't try debug ip nat. I'll do whenever i can.


olafmarcos Tue, 04/17/2007 - 15:46
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I can run the proposite doing:

ip nat inside source static interface Dialer0

and permitting in the "acl in" of Dialer:

access-list 102 permit udp any any range 10001 20000

but this implies that if i need to nat anoother range to another Internal_IP, I can't. I only can map the external Dynamic_IP to one Internal_IP.

Is this a cisco limitation?

Is there any way?




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