Possible NAT issue

Unanswered Question
Sep 30th, 2008

Hello All,

I use a 2611XM to route voice traffic. I use two ISPs for failover. I use IP SLA to track the interface and do a failover. Here's the configuration.

track timer interface 5

track 123 rtr 1 reachability

delay down 15 up 10

!

track 345 rtr 2 reachability

delay down 15 up 10

interface FastEthernet0/0

ip address 192.168.1.1 255.255.255.0

ip nat inside

interface FastEthernet0/1

ip address 182.65.23.52 255.255.252.0

ip nat outside

interface Dialer1

ip address negotiated

ip nat outside

ip route 0.0.0.0 0.0.0.0 182.65.23.1 track 123

ip route 0.0.0.0 0.0.0.0 Dialer1 5

ip access-list extended NAT

permit ip 192.168.0.0 0.0.0.255 any

ip nat inside source route-map CABLE interface FastEthernet0/1 overload oer

ip nat inside source route-map DSL interface Dialer1 overload oer

ip sla 1

icmp-echo 182.65.23.1 source-interface FastEthernet0/1

timeout 1000

threshold 40

frequency 3

ip sla schedule 1 life forever start-time now

ip sla 2

icmp-echo 4.2.2.2 source-interface Dialer1

timeout 1000

threshold 40

frequency 3

ip sla schedule 2 life forever start-time now

route-map CABLE permit 10

match ip address NAT

match interface FastEthernet0/1

!

route-map DSL permit 10

match ip address NAT

match interface Dialer1

The problem is that any time an ISP goes down and the other ISP become primary path, I have to clear NAT statement from the router and reboot the phone. I am using an Asterisk based IP PBX as Call Manager and Linksys phones.

Any help on this would be highly appreciated.

Thanks and Regards

OJ

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rais Tue, 09/30/2008 - 10:25

Have you tried setting timeout seconds for NAT to a lower value?

Thanks.

rais Fri, 10/03/2008 - 11:25

Can't think of anything else. May be bringing up the other interface after same amount of time that NAT expires in would help.

Rais.

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