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I got a server with XenServer 6.0.2 and this server has 3 nic with 3 different ip addresses, because I am using 3 different subnet The first 2 card are working and from the first 2 subnet I have access to internet, the third one is the problem. Basically the hosts in the last subnet can ping each and other but I if try to ping the gateway I got

 Destination Host Unreachable

and is not finished here. Trying to ping the gateway outside the subnet I got

PING 87.117.221.17 (87.117.221.17) 56(84) bytes of data.
From 87.117.211.46 icmp_seq=1 Time to live exceeded

What does it means? I saw the configuration of each host in the 3rd subnet and the nic interfaces is setup to use the 3rd card. Every host in the 3rd subnet has in the /etc/network/interfaces the right ip addresss for the gateway.

Any thoughts?

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Please post your routing table so that we can see what is going on.... route -n Thanks –  Leoric80 Jan 16 at 10:28

3 Answers 3

The most probable cause is: the gateway is down.

Check if the gateway (router) is up, check the IP (if it's set correctly), check if you can ping the computers from that gateway, and if there is no firewall rule blocking pings/traffic to the gateway.

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Unfortunately the server is in co-location outside the country so I don't have opportunity to check. If I ping the gateway from the subnet I got Destination Host Unreachable, instead if I ping the gateway outside the subnet from my laptop I got Time to live exceeded . Anyway I'll try to contact the support –  marcodv Aug 13 '12 at 13:13
    
If you ping it from your lan, it does not get an ARP reply; that's why you get "Destination Host Unreachable". If you ping it from outside, the last router on the way sends the "TTL exceeded". Why? No way to know without access. Support would be the best solition for this. –  mulaz Aug 13 '12 at 13:30
    
ok I'll try that and I'll let you know. –  marcodv Aug 13 '12 at 13:47

If you run a traceroute, you'll probably see it bounce between two hops. This often happens when a route is missing.

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Could be that you made a loop with routing? TTL is reduced by 1 at every hop, and will cancel the packet if it reaches 0. To prevent circling packets all over the internet.

Anyway give routing tables a tough check again. Might be there is a small bug inside...

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