Finisar Surveyor - Manual (Page 271)

10-67
Expert Features
Network Layer
10
ICMP Destination Network Unknown
Counter
ICMP Destination Network Unknown events are counted in the ICMP All Errors
and the ICMP Destination Unreachable counters. A count of all destination
unreachable ICMP symptoms and a count of all ICMP errors displays in the
Overview counters of Expert View. A threshold can be set in Expert Alarms for all
destination unreachable ICMP errors or for all ICMP errors.
Expert Symptom
ICMP Destination Network Unknown events are automatically logged as expert
symptoms. The
Symptom Summary field provides information about the IP
addresses involved. For example:
[206.250.228.69] cannot be reached by [206.250.228.11].
SA=[206.250.228.11] DA=[206.250.228.69]
Diagnostic Details
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Problem Description:
An ICMP Destination Network Unknown message has been sent.
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Probable Cause(s):
1. If a router has a routing table problem, it may send this message.
2. A router may send this message if it does not know the destination network.
3. The source may have an incorrectly configured subnet mask.
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Recommended Action(s):
1. Check the routing tables of the router that this message was generated from.
2. Check the netmask configuration of the source and/or the router.
3. Ignore this message if the network is truly unknown (no action required).