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Cisco Bug: CSCuj58299 - CUBE Input queue wedge RTCP packets - 180w/o SDP followed by 180w/SDP

Last Modified

Apr 24, 2020

Products (1)

  • Cisco IOS

Known Affected Releases

15.1(0.0.4)

Description (partial)

Symptom:
Interface input queue starts to become congested.  The input queue can reach the input queue maximum which will cause problems for all control-plane and punted traffic (management, routing protocols, call control, etc).  

Example from "show interface" output:

Input queue: 76/75/0/5549 (size/max/drops/flushes); Total output drops: 0

It may seem like the router becomes "unresponsive" and may require a reboot to restore service.  Access from the console will still be possible.  After some time, the input queue can clear on it's own.

Conditions:
This symptom is observed under the following conditions:
1) Router serves as a SIP-SIP CUBE
2) Packets that are congesting input queue are RTCP packets.  Check  "show buffers input-interface [interface] packet". (RTCP packets are most commonly odd source/destination UDP ports in the range 16384 - 32768)
3) CUBE receives a 180 without SDP followed by a 180 with SDP on one of the call legs (collect 'debug ccsip message' for a period of time leading up to and including when you see the input queue begin to fill)
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Bug Details Include

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