Question : Windows 2003 tcp/ip not working, but arp (layer 2) does work.

I have this bizare problem with a win2003 server (applicance edition). I have lost all my network connectivity.

When I do a ping to an ip address on the same network I recieve the error "destination host unreachable". Usually you only see this error is something is wrong with IP routing (e.g. you don't have a gateway filled in).
But I do have a gateway. And my routing table looks fine.

Further investigation learned me:
- Arp is functioning just fine for incoming connections. So pinging the troubled server for another machine on the same network makes the MAC adress show up in the arp table of both machines
- Arp is not working when I try to ping a host on the same network from the troubled server.
- When I start network monitor I see all broadcast traffic on the network coming in just fine. I also see the ICMP request coming in from my workstation.

I have tried:
- doing a netsh int ip reset
- doing a winsock reset
- emptying the routingtable
- removed appletalk
- unstalling the last installed windows updates
- connecting the second NIC of the server

and all didn't help.

I hope some of you have any smart ideas....

Answer : Windows 2003 tcp/ip not working, but arp (layer 2) does work.

The problem was because IPsec isolation was turned on.