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HiSpeed Switch Troubleshooting Guide
10-4
US7070447-001, Rev 01
Draft Level—Hitachi Confidential
Common ICMP Destination Unreachable Messa
g
es
Network Unreachable
This message is sent by a router indicating that it cannot reach the specified
network. This may be a result of a misconfigured mask, link down, missing route,
or an invalid network.
1.
Is the specified destination address a valid network?
2.
Is the link up from the router sending the Network Unreachable message?
3.
Is the port in the router configured with the correct subnet mask?
4.
Does the route exist in the routing table?
Host Unreachable
This message is sent by a router indicating that the destination host did not
respond. The significance of this implies that the intervening network
infrastructure is working properly and the frame has successfully arrived at the
last router in the path. The ARP request to the destination host did not respond.
This may be a result of a user typing an incorrect IP address or a high number of
physical layer errors on the destination network.
1.
Is the destination IP address correct?
2.
Is the destination host available?
3.
Are there any physical layer problems on the destination network?
4.
Is the default gateway correctly defined on the destination device?
5.
Verify that the destination device can ping its default gateway. From the ARP
table of the destination device, is the default gateway address learned?
Port Unreachable
This message is sent by the destination host device indicating that the port process
is not functioning properly or does not exist. One of the most common Port
Unreachable errors occurs when an SNMP manager is polling a device on the
network which didn’t have an SNMP agent configured on it.
1.
Is the port process enabled or running?
2.
Find out what the port is used for and why isn’t it available. Refer to RFC
1700 for a complete list of well-known ports.