Trouble routing over P2P T1 - Bad config

lidanny-half · ‎05-19-2005

I have set up my routers on each end of a leased line. On one of my machines the default gateway is 10.0.0.11 which is the ip address of FE0 on the router at the main office. From this machine which is 10.0.0.200 I can ping all the way through the line to FE0 on the remote router but I cannot ping the ip address of a laptop on that side. The laptop is connected to a switch on that side and so is FE0. I am attaching my configuration. Any help would be appreciated. I would also like to be able to use DNS to resolve names over this line. The machine that I am trying to ping from 10.0.0.200 is a windows 2000 server with the role of domain controller and the only machine which needs to comunicate with the remote site. It is also our DNS server.

dgahm · ‎05-19-2005

Your symptom is consistent with the laptop having a bad default gateway address. The ping gets to the laptop, but the laptop is unable to ARP for the MAC address of the default gateway, so the return fails.

The default router (gateway) for a PC on a network must be a router address on the same subnet. Your 10.1.3.2 should be using 10.1.3.1 for a default router. Your DHCP pool has 10.1.1.1 for the default router, which will not work. I see that 10.1.3.2 is excluded from the DHCP pool, but the gateway may have been statically set wrong. If you enable proxy arp on the FE port it would work, but you should really use the FE address as the gateway.

lidanny-half · ‎05-20-2005

That makes sense and I was wondering about the default gateway on the laptop especially since I was able to go into the router using SDM over Internet Explorer and you know when you choose Interfaces then Edit Interfaces then test it performs a ping test. Well when I choose FE on the remote router I get the following when using the Automaticaly Determined By SDM option: Checking Exit Interface -> Failed and the reason is No configured DNS servers are routable through the selected interface. Under details it says it is checking serial 0/0. But when I specify the ip as 10.1.3.2 then the ping test succeeds. It is from a dos command line that the ping fails. So if I fix the gateway settings on the laptop (it is static, dont remember what I used) and the the gateway setting for the DHCP pool, do you think I will be able to comunicate with a server using the name only? I guess if I add an entry to the local Hosts file it should ensure that I can. Thanks for your advice, I will try it out and let you know and based on the above I would appreciate any additional thoughts you might have.

dgahm · ‎05-20-2005

If the address of the name server is reachable on your network then DNS should work fine.

When you use a domain name the PC will send a port 53 UDP packet to the DNS server requesting the IP address for that name. The DNS server address is either learned via DHCP or statically entered. You should not need a Hosts file entry. That is only needed if you do not have a DNS server.