[c-nsp] Intermittent Port Forwarding Problems with New-Style NAT

[Gary T. Giesen]

I have a router (2821, running 15.1(4)M8) with the following config:

interface Dialer1
 Internet PPPoE
 mtu 1492
 ip address negotiated
 ip nat enable
 encapsulation ppp
 ip tcp adjust-mss 1452
 load-interval 30
 dialer pool 1
 keepalive 5
 ppp pap sent-username user.name password pass123
end

interface GigabitEthernet0/0
 DSL Modem
 no ip address
 duplex auto
 speed auto
end

interface GigabitEthernet0/1
 description LAN Switch
 ip address 192.168.1.1 255.255.255.0
 ip nat enable
end

ip access-list extended NAT_HOSTS
 10 permit ip 192.168.1.0 0.0.0.255 any

ip nat source list NAT_HOSTS interface Dialer1 overload
ip nat source static tcp 192.168.1.3 3389 interface Dialer1 3389



What I'm randomly encountering is the port forward will stop working,
and I have to remove and re-add the line:

ip nat source static tcp 192.168.1.3 3389 interface Dialer1 3389


It's difficult to reproduce as it appears on random intervals, and I
need to restore service so I don't have a lot of time to troubleshoot.
Has anyone ever encountered this before? I'm pretty sure my config is
sane but feel free to point out if it is not. The problem does not
seem to occur if I use the old style nat (ip nat inside/ip nat
outside) but the new-style nat is much preferable for its flexibility.
It also doesn't affect the PAT.

Cheers,

GTG