Access another router connected to the Cisco 871 WAN port via LAN device

[itlengineering]

We are using a Cisco 871 in our data center, which is setup as follows:

- FastEthernet0 port on the Cisco 871 (192.168.1.1) connects to an unmanaged switch, which is used to connect all of our LAN devices to the Cisco

- The WAN port on the Cisco connects to a LAN port on a non-Cisco router (192.168.2.1), and negotiates its IP address via DHCP

- The WAN port on the non-Cisco router has a LAN cable that connects to our ISP

- The Cisco 871 establishes a connection to the Internet via PPPoE

At present, we are able to ping the non-Cisco router from the Cisco router, but we are not able to ping the non-Cisco router from a device on the Cisco local LAN (192.168.1 subnet). I'm thinking that an ACL rule or static route needs to be in place on the Cisco in order to get this working, but I'm not exactly sure how to implement this. If anyone has any idea how this can be set up, it would be greatly appreciated.

Best Regards,

Steven

[Omegatek1]

Steven,

If your C871 has an interface in both networks, from that router's standpoint...a static route isn't necessary for the two networks to "speak."  The C871 already knows.   However, I'll bet it's the other two variables (the local LAN or non-cisco router) that may be the issue.  I would recommend:

1. Make sure your devices on your local LAN (192.168.1.x) have their default gateway configured to use the C871

2. Check the non-cisco router to make sure that it has a route back to 192.168.1.x; assuming you're not running a basic routing protocol

It's hard to tell you what command to use for injecting that route on the non-Cisco router without knowing the platform.  Let me know what you find out.

[Ganesh Hariharan]

We are using a Cisco 871 in our data center, which is setup as follows:
-
FastEthernet0 port on the Cisco 871 (192.168.1.1) connects to an
unmanaged switch, which is used to connect all of our LAN devices to
the Cisco
- The WAN port on the Cisco connects to a LAN port on a non-Cisco router (192.168.2.1), and negotiates its IP address via DHCP
- The WAN port on the non-Cisco router has a LAN cable that connects to our ISP
- The Cisco 871 establishes a connection to the Internet via PPPoE
At
present, we are able to ping the non-Cisco router from the Cisco
router, but we are not able to ping the non-Cisco router from a device
on the Cisco local LAN (192.168.1 subnet). I'm thinking that an ACL
rule or static route needs to be in place on the Cisco in order to get
this working, but I'm not exactly sure how to implement this. If anyone
has any idea how this can be set up, it would be greatly appreciated.
Best Regards,
Steven

Hi Steven,

You need to ask your ISP end non cisco devices to drop a reverse route for your lan subnet 192.168.1.x towards your cisco 871 wan end.This will create connection between lan and non cisco router.

Right now your lan can ping the cisco 871 interface only not the non cisco devices wan ip also once you drop a reverese route you will able to ping.

Hope to Help

Ganesh.H

[itlengineering]

Thanks for your help guys! I will dig a little deeper into the configuration of the non-cisco router to see if what you are suggesting is possible.

Best Regards,

Steven