Finisar Surveyor, User Manual

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10-68
Surveyor
User’s Guide
ICMP Destination Unreachable
ICMP Destination Unreachable is a counter of all ICMP destination unreachable
errors over a period of time per segment. A count of all destination unreachable
ICMP symptoms displays in the
Overview
counters of Expert View. A threshold for
this counter can be set in Expert Alarms for all destination unreachable ICMP
errors.
The following types of destination unreachable ICMP errors are counted:
Network Unreachable, Host Unreachable, Protocol Unreachable, Port Unreachable,
Fragmentation Needed [D/F Set], Source Route Failed, Destination Network
Unknown, Destination Host Unknown, Destination Network Access Denied,
Destination Host Access Denied, Network Unreachable for TOS, Host Unreachable
for TOS, Destination Unreachable (catches all other Destination Unreachable
Errors)
Expert Symptom
ICMP Destination Unreachable is also an expert symptom, and has its own
Diagnostic Details. However, this expert symptom reflects only those destination
unreachable conditions which cannot be assigned to one of the other destination
unreachable symptoms defined above.
ICMP Destination Unreachable 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 Unreachable 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 host may send this message if a destination is unreachable.
3. If the packet needs to be fragmented and the “don’t fragment” flag is set the
host/router will send this message.
4. The source may have an incorrectly configured subnet mask.