Why does pinging a local router return "Destination Host Unreachable"?

Posted by Matt H on Super User See other posts from Super User or by Matt H
Published on 2011-08-05T02:38:59Z Indexed on 2012/06/22 9:18 UTC
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I have two tomato routers. One is bridged wirelessly with the other.

I have a new server on the network. It's running Ubuntu Server 11.04.

They are all connected like this:

A - Linux PC
B - New Server
C - Mac Mini
D - Macbook
T1 - Tomato 1
T2 - Tomato 2

They are connected like so:

A -----+-T1  ==== wireless bridge ==== T2----- ADSL modem
       |                               | C & D Connected wirelessly to T2
B -----+

A, C & D do not experience any issues.

I have an active SSH session to B from A and it's not experiencing any loss.

B, the new server occasionally cannot ping T2 and therefore cannot connect to the internet. However, A can always contact B and B can ping A and B When the network is lost, B can still ping T1, but not T2 yet at the same as B has lost connection to T2, A can still ping T2.

Any ideas on what this could be? there is nothing that gives any clues in any of the logs on either router or the linux server.

One thing that is interesting is that I set up a ping running between B and T2. T2 has the IP address 192.68.1.1

Here is what I am seeing:

From 192.168.1.1 icmp_seq=26 Destination Host Unreachable
From 192.168.1.1 icmp_seq=27 Destination Host Unreachable
From 192.168.1.1 icmp_seq=28 Destination Host Unreachable
From 192.168.1.1 icmp_seq=29 Destination Host Unreachable
From 192.168.1.1 icmp_seq=30 Destination Host Unreachable
From 192.168.1.1 icmp_seq=31 Destination Host Unreachable
From 192.168.1.1 icmp_seq=33 Destination Host Unreachable
From 192.168.1.1 icmp_seq=34 Destination Host Unreachable
From 192.168.1.1 icmp_seq=35 Destination Host Unreachable
64 bytes from 192.168.1.1: icmp_req=36 ttl=63 time=3.40 ms
64 bytes from 192.168.1.1: icmp_req=37 ttl=63 time=5.70 ms
64 bytes from 192.168.1.1: icmp_req=38 ttl=63 time=2.25 ms
64 bytes from 192.168.1.1: icmp_req=39 ttl=63 time=2.18 ms
64 bytes from 192.168.1.1: icmp_req=40 ttl=63 time=3.12 ms
64 bytes from 192.168.1.1: icmp_req=41 ttl=63 time=2.15 ms
64 bytes from 192.168.1.1: icmp_req=42 ttl=63 time=1.97 ms
64 bytes from 192.168.1.1: icmp_req=43 ttl=63 time=

And it cycles to being reachable and not.

So I guess you could say the question is, why is the router responding that it cannot be reached?

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