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Community Member

Routing Problem ??

I have a 3640 connecting to a 1601 via a 256k kilostream link. From the 3640 I can ping all the interfaces on the 1601 and the Internal LAN, but when I try to ping the 3640 LAN from the 1601 I get the reply from the WAN address on the 3640 saying the LAN address "destination host unreachable" BUT if I create a telnet session from the 3640 to the 1601 I can ping everything from the 1601. Can anyone help me ?

I am using static routing and all the routes when I use show ip route are there.

12 REPLIES
Community Member

Re: Routing Problem ??

Hi

Are u able to ping 1601 and its LAN from 3640's LAN ? I think LAN pkts are being dropped at the gateway.. chk IP route for your LAN's IP's.

Community Member

Re: Routing Problem ??

Hi

From the 3640 LAN I can ping the 1601 interfaces and the entire LAN without a problem. I'm confused on why it work's once I have telnetted from the 3640 to the 1601 but as soon as I close the telnet session the 1601 LAN can't see the 3640 LAN.

Community Member

Re: Routing Problem ??

hmmm. i've had a similar problem before and it turned out to be that my cat6k had some bad routes in its table and was somehow stealing MAC addys and broadcasting some strange traffic. My first thought on your problem is that this may be an ARP cache problem somewhere. Clear all your mac tables and make sure there's no strange broadcast traffic going on.

Community Member

Re: Routing Problem ??

ya Kangin .. I agree with you ... there might be some routing issues or a bad ARP Cache..

Dave, if you are still unable .. show your routs defined .. here with all the ip pools on both the routers..

Community Member

Re: Routing Problem ??

Hi

I have cleared the arp cache on both routers but still with no success. Below is the config for both routers

3640:

Int fa0/1: 172.16.30.1

Int s0/1: 172.16.20.1

Table:ip route 0.0.0.0 0.0.0.0 serial0/0

ip route 172.16.10.0 255.255.255.0 172.16.20.2

1601:

Int eth0: 172.16.10.1

Int s0: 172.16.20.2

Table: ip route 172.16.30.0 255.255.255.0 172.16.20.1

Community Member

Re: Routing Problem ??

Do you have any strange access lists? Also, when running a traceroute from the 1601 to the 3640 where does it fail?

Community Member

Re: Routing Problem ??

At the moment there are no access list's specified as this system has not gone live yet. The traceroute gets as far as the s0/1 port on the 3640 and fails on the fa0/1 port. The message I get is "destination host unreachable".

Thanx for your help so far.....

Community Member

Re: Routing Problem ??

ok, are you natting? it almost sounds like it can't reach a private address range for the LAN after coming in over the serial interface. this may be better if you post your configs by the way. it will go faster at least :). email me at jevansAU99@yahoo.com if you don't want to post your configs on the board.

Community Member

Re: Routing Problem ??

Hello Dave

You have given WAN IP to se 0/1 and your default IP root is 0/0 .. why is that ? Would you like to answer ?

Community Member

Re: Routing Problem ??

The reason for the default root on s0/0 is that it is our internet connection.

Community Member

Re: Routing Problem ??

hi,

why you don't have the line

ip route 0.0.0.0 0.0.0.0 serial0/0

in 1601?

the issue is: from the LAN 1601 can you ping 172.16.20.1?

HTH

Mauricio

Community Member

Re: Routing Problem ??

Hi Dave

Have you configured VLAN .. on your LAN switch ? If yes then that should be trunked with Router on the Fast ethernet port sub interface(s).

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