router's default gateway

[kostica]

Hello,

I have problem to configure my Cisco router to work in a LAN with one more 3G router.

LAN is connected to the 3G router which forwards traffic to Cisco which is used as a gateway to Internet.

Cisco has default route to its WAN

1. ip route 0.0.0.0 0.0.0.0 wan_interface

I want to forward all the traffic which comes from the Internet to the 3G router. Something like this:

2. ip route 0.0.0.0 0.0.0.0 ip_address_of_3g_router

But this way I have two default routes on my Cisco. How to differ traffic which should go outside (and which should use first default route) from the traffic going inside (which should use second default route).

Hope I was clear what I intend to configure here. Do you have any suggestion?

[Ma'moun Mohammad shanableh · Accepted solution]

Hello,

As you know, you cannot use more than one default route on the same router, so if this is your problem and i am understanding the question in a right way, then the solution is by using a PBR Policy Based Routing, with PBR you can differentiate between the traffic and its next hop lets say, with a use of an access list.

http://www.cisco.com/en/US/docs/ios/12_0/qos/configuration/guide/qcpolicy.html

Try to refer to the above link to read about the PBR.

Another solution is to use a VRF, but in this case the two networks that you will create will be seperated and every one will have its own routing table, I think that the PBR is what you are looking for.

Cheers...

Sent from Cisco Technical Support iPad App

[Jeff Van Houten]

Another solution is a static route. There can be only one default, but a more precise route will be favored over a more generic route. Put in a static for the internal network and leave a default for everything else.

Sent from Cisco Technical Support iPad App

[darren.g]

kostica@impcomputers.com wrote:
Hello,
I have problem to configure my Cisco router to work in a LAN with one more 3G router.
LAN is connected to the 3G router which forwards traffic to Cisco which is used as a gateway to Internet.
Cisco has default route to its WAN
1. ip route 0.0.0.0 0.0.0.0 wan_interface
I want to forward all the traffic which comes from the Internet to the 3G router. Something like this:
2. ip route 0.0.0.0 0.0.0.0 ip_address_of_3g_router
But this way I have two default routes on my Cisco. How to differ traffic which should go outside (and which should use first default route) from the traffic going inside (which should use second default route).
Hope I was clear what I intend to configure here. Do you have any suggestion?

How big is your "internal" address space?

Instead of the second line reading

ip route 0.0.0.0 0.0.0.0 ip_address_of_3g_router

Can you not make it read

ip route 172.16.0.0 255.255.0.0 ip_address_of_3g_router?

Of course, you put your own "internal" LAN address subnet instead of 172.16.0.0 255.255.0.0 - you can also add multiple lines if you have multiple subnets which aren't easily summarized, I.E.

ip route 192.168.1.0 255.255.255.0 ip_address_of_3g_router

ip route 192.168.25.0 255.255.255.0 ip_address_of_3g_router

ip route 10.100.1.0 255.255.255.0 ip_address_of_3g_router

And continue for as many internal subnets as you like.

This is much easier than mucking around with PBR! Hell, for that matter, setting up OSPF would be easier than mucking around with PBR.

Cheers.