NAT with different ISP

[Lingfeng Xiong]

I have a router connected to two WANs and one LAN. All clients in LAN should be able to access these two WAN networks. IP addresses allocations for these networks are:

LAN: 172.16.0.0/16

WAN1: 10.224.128.0/17

WAN2: Internet

The router needs to do PAT for all internal clients, forward the traffic to corresponding WAN ports based on destination address.

Currently, I configured my router like this:

ip nat inside source list 100 interface GigabitEthernet0/0.35 overload
ip nat inside source list 101 interface GigabitEthernet0/0.34 overload
!
access-list 100 deny   ip any 10.224.0.0 0.0.128.255
access-list 100 permit ip any any
access-list 101 permit ip any 10.224.0.0 0.0.128.255
access-list 101 deny   ip any any

But it seems all traffic are sending from the Gi0.35, no traffic send from Gi0.34.

The routing table is

S*    0.0.0.0/0 [254/0] via 47.55.212.1
      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.224.128.0/17 is directly connected, GigabitEthernet0/0.34
L        10.224.190.xxx/32 is directly connected, GigabitEthernet0/0.34
      47.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        47.55.212.0/22 is directly connected, GigabitEthernet0/0.35
L        47.55.214.xxx/32 is directly connected, GigabitEthernet0/0.35

[Reza Sharifi]

The reason traffic is using Gi0.35 is because the default route is poinging to Gi0.35 which is:

0.0.0.0/0 [254/0] via 47.55.212.1

You also need a default route with a different metric pointing to Gi0.34

HTH

[Lingfeng Xiong]

Hi Reza,

I am a bit confused... The WAN of Gi0.34 only serve the network of 10.224.128.0/17. If I place a default route from that interface, wouldn't I get into trouble?

Also, for the network 10.224.128.0/17, I believe there is already a route to that network from Gi0.34. It is shown in routing table:

C        10.224.128.0/17 is directly connected, GigabitEthernet0/0.34

Thank you.