Solved: Problem pinging internal host from WAN

jdamone · ‎06-12-2010

I have a single host at a site I cannot ping through our WAN interface on the router, yet I can ping any other host on the LAN remotely. This host is reachable and can be pinged locally at the site. When I do a traceroute from the main site, the ping stops at the serial interface of the router. When I check the router for a route to this host, a route exists.

I'm wondering what could be preventing me from communicating with this specific host remotely.

I don't know if this helps but we have several sites set up the same way, and with 3 of the sites we have this problem. The sites that are working have Cisco 2600 series routers. The sites that aren't working have Cisco 1800 series routers. The remote host that we cannot reach is configured statically with 192.168.x.254.

Some assistance troubleshooting would be helpful.

Thanks

Reza Sharifi · ‎06-12-2010

John,

If it has multiple interface and there are multiple subnets involved in your network, then the Linksys must have some sort of static route for your other locations to be able to reach it.

Also, if you have diagram you can post maybe I can help you better.

HTH

Reza

View solution in original post

Reza Sharifi · ‎06-12-2010

Hi,

Does the host you can not ping has a default gateway?

Is the host you can not ping located in the same subnet as the once you can ping?

Reza

jdamone · ‎06-12-2010

Hi

Reza,

The host is on the same subnet as all the other hosts on the LAN, and is pingable from any host on the LAN. The host is a Linksys router with it's LAN interface connected to the same switch as all the other hosts on the LAN.

John

Reza Sharifi · ‎06-12-2010

Hi John,

Ok, so does this Linksys router have a default route or default gateway?

Reza

jdamone · ‎06-12-2010

Reza,

It has a WAN interface that goes out to the public internet. We didn't configure a default route or gateway, but I'm sure there is a routing table on the device.

John

Reza Sharifi · ‎06-12-2010

John,

If it has multiple interface and there are multiple subnets involved in your network, then the Linksys must have some sort of static route for your other locations to be able to reach it.

Also, if you have diagram you can post maybe I can help you better.

HTH

Reza

jdamone · ‎06-12-2010

Hi Reza,

Give me some time to post a diagram so as not to cause any confusion.

Thanks,

John

jdamone · ‎06-12-2010

From the Corporate MPLS network, I can ping the serial interface (172.16.0.54) and any 192.168.208.x host within the LAN except 192.168.208.254.

From within the LAN I can ping 192.168.208.254 from the Cisco 1800 router and from any other host on 192.168.208.x.

I'm not sure why I can't get past the serial interface to 192.168.208.254.

John

Reza Sharifi · ‎06-12-2010

John,

On the Linksys you need a default route toward the outside (Internet) and specific static route towards the inside 172.16.0.0 subnet

I think the reason you can't reach 192.168.208.254 is because the Linksys doe not have route back to the 172.16.0.0 subnet

Reza

jdamone · ‎06-12-2010

Reza,

I figured it out. Proxy Arp needed to be enabled on the ethernet interface. I really appreciate your input though.

Thanks,

John