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Cisco Bug: CSCup89543 - Packet with MTU 1496 above fails when using local span

Last Modified

Aug 15, 2017

Products (1)

  • Cisco Catalyst 4000 Series Switches

Known Affected Releases

15.2(1)E 3.6(3)E 3.7(0)E

Description (partial)

Symptom:
with Default MTU 1500 set .
we configure LOCAL SPAN session :

-----------------------
monitor session 1 source interface Po4
monitor session 1 destination interface Te1/1/16 
monitor session 1 filter packet-type good rx  ---------- > this line is added automatically
-----------------------
here , no issue is seen .
all packets within MTU limits go through.

however , if you REMOVE "monitor session 1 filter packet-type good rx" MAnually ,
all packets with MTU > 1495  is dropped.

Conditions:
span is set on 4500X VSS without 'filter packet-type good rx'
ping from PC with packet size which is more than 1469 fails
span source port is configuring as trunk mode.

issue is seen in VSS as well as standalone .
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