Eiu Overload Control; Table 27 Eiu Lan Fault Leaky Bucket Parameters - Nortel DMS-100 User Manual

106 Chapter 4: EIU maintenance
Table 27 summarizes the preset bucket parameters for reported LAN faults.

Table 27 EIU LAN fault leaky bucket parameters

Bucket name Bucket size
Receive 3000
framing error
Receiver 3000
overflow
Receive CRC 3000
Transmit 60
Deferred
Loss of carrier 30000
Late collision 300
Transmit 300
retries
exceeded

EIU overload control

In an overload situation, the EIU overload control discards packets at the
interrupt level rather than at the process level.
The feedback scheme is devised such that packets received either from the
Ethernet interface or F-bus interface are discarded when the EIU resources
reach critical condition. The EIU can withstand a broadcast storm or a
babbling node due to overload controls that have been implemented. This level
of robustness follows standard DMS maintenance philosophy: a node must be
maintainable even under overload conditions.
Lab tests show that a moderately loaded LAN with broadcast messages
resulted in the workstation and the router locking up while the EIU remained
functional. The workstations were overloaded to the point that all activity
within the operating system stopped:
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•
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•
•
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297-8991-910 Standard 03.01 August 1999
Threshold
set level
3000
3000
3000
30
30000
300
300
the on-screen clock stopped ticking
the cursor did not respond to mouse movements
keystrokes were ignored
outgoing LAN activity stopped
programs were not aware that a period of time had elapsed
the router stopped routing packets
Threshold Error event
clear level count value
2970 1000
2970 1000
2970 1000
15 1
29940 10000
270 10
270 10
Good event
count value
1
1
1
1
1
1
1