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Global service was affected due to broadcast in vsi of CX600

Publication Date:  2012-07-27 Views:  175 Downloads:  2

Issue Description

See topology in attachment,when fiber was broken in  point X,all the service was affected globally.

Alarm Information


Handling Process

Because this problem included many devices, so we focused on one service from RNC to NodeB (see attachment "topo 2"). The ports of CX600 A were G1/1/1 and G1/1/19 in this service. Checking port statistic, we found there's packet loss in history.

<CX600 A>display port-queue statistics interface GigabitEthernet 1/1/1 ef outbound
 Current usage percentage of queue: 0
  Total pass:
  186,156,407,829 packets,         54,729,983,866,753 bytes
  Total discard:
  3,035,671,974 packets,            992,681,124,613 bytes

Checking port configuration, we found there's port shaping about EF queue. It's possibly that packet loss caused service interruption.

<CX600 A>display  current-configuration interface  GigabitEthernet  1/1/1
interface GigabitEthernet1/1/1
 port-queue ef pq shaping 100 outbound

Analyzing the traffic model, in normal case,service of CX600 A's g1/1/1  is 70M. When CX600 B's downstream link was broken, CX600 A's PTN mac address would be aged, meanwhile, PTN C always sent traffic to PTN D. So this part of traffic(40M around) would be broadcasted in all CX600, , so CX600 A's port bandwidth,100M, was insufficient. As a result, service was broken.

Since we know the root cause, we apply the unknown uni-cast suppression in CX600 A, after that, problem is solved.


Root Cause

1.RNC has problem.

2.Switch has problem

3.PTN has problem

4.CX600 has problem


It’s suggested that under sub-interface GigabitEthernet1/1/17.3101, GigabitEthernet1/1/17.3801, GigabitEthernet1/1/19.3101 and GigabitEthernet1/1/19.3801 of CX600 A, which are connected to PTN, configuring unknown uni-cast suppression, limiting the unicast traffic to 1M, so that, when some PTN is down, most of the unknown uni-cast traffic will be discarded in CX600 A, only 1M traffic is left to broadcast, when PTN gets up again, CX600 will learn its MAC address by such broadcast, after that, traffic should be sent in uni-cast mode.