Finisar Surveyor, User Manual

Page: 269 / 454

10-65
Expert Features
Network Layer
10
ICMP Destination Host Unknown
Counter
ICMP Destination Host 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 Host 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 Host 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 host.
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 host is truly unknown (no action required).