Cisco 4330 NAT

[Irakli Gvishiani]

Hello,

I have one issue regarding PAT. We are trying to register our local Phone server to ISP SIP server. On our local Phone Server we have private IP and the we do PAT for accessing to internet. And during this PAT I see that the source port of is changing. How I can disable source port changing during PAT?

[Irakli Gvishiani]

Or how I can manually set static source port just for one host? 

[balaji.bandi]

post the config ?

 show run

(removing any passowrd)

[Irakli Gvishiani]

interface Port-channel1.395
description Internet
encapsulation dot1Q 395
ip address *.72.*.102 255.255.255.248
ip nat outside



ip nat inside source route-map NAT interface Port-channel1.395 overload
ip route 0.0.0.0 0.0.0.0 *.72.*.97 name Default-Gateway track 255

ip access-list extended NAT
220 permit ip host 10.10.3.10 host *.67.*.200
230 permit ip host 10.10.3.10 host *.157.*.124

route-map NAT permit 10
match ip address NAT

[Irakli Gvishiani]

There is no any additional config

[balaji.bandi]

as per the information provide you have NAT using your port-channel interface

check the example

route-map

with NAT

https://community.cisco.com/t5/networking-knowledge-base/how-to-configure-static-nat-with-route-maps/ta-p/3132855

coming back to your question what is the need to source port change in NAT ?

[Irakli Gvishiani]

There is some issue regarding SIP registration. ISP told me that he saw registration sourced with

port 65060

but when I was checking NAT was with

port 8172

[Irakli Gvishiani]

I also have in another office Cisco 800 Router and there is no port changing during the NAT

[Irakli Gvishiani · Accepted solution]

I changed NAT configuration from interface to IP NAT Pool and right now source ports are the same. 

[balaji.bandi]

glad all good and thank you sharing the solution

[guruvignesh]

Hello Irakli,

To maintain the source port during PAT, you can't use traditional PAT. Instead, consider using a static NAT or port forwarding (Static PAT) rule that maps your internal phone server's IP and desired source port to a specific external port on your public IP address. This keeps the source port consistent for your SIP communication.