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Cisco Bug: CSCvu65464 - Auto recovery mechanism when the chunk is full and dhcp packets stay in chunk for a long time

Last Modified

Aug 24, 2020

Products (1)

  • Cisco ASR 9000 Series Aggregation Services Routers

Known Affected Releases

6.4.2.ROUT

Description (partial)

Symptom:
DHCP relay stops working
DHCP stops processing packets

Conditions:
From the above, we can roughly summarize the following to have been transpired in the customer setup:
a.	There was L2 Flood, and DHCP was busy handling the L2 notifications.
b.	In parallel, there were DHCP Relay packets coming in via BVI interface. These were allocated the chunk, but never dequeued as the DHCP was busy. Hence the chunk allocation kept on incrementing.
c.	Eventually the chunk allocation was full ? ie reached 11000, and remained there.
d.	Then the customer removed that BVI from the DHCP profile (tacacs log clearly show that customer had removed few interfaces from DHCP profile)
e.	Later on, when the L2 Flood was calmed down, the new arriving packets, hit the chunk-allocation issue, and silently failed due to rx_malloc_fail.
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