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VSP Excessive Topology Change BPDUs Received On NNI Link Results In High CPU Utilization Leading To A Potential System Crash

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TitleVSP Excessive Topology Change BPDUs Received On NNI Link Results In High CPU Utilization Leading To A Potential System Crash
Symptoms
  • Excessive number of topology change notifications received on NNI (Network Node Interface) or SPBm (Shortest Path Bridge Mac) enabled links may cause High CPU utilization resulting in a system reset.
  • Port statistics will indicate excessive number of Rx TC BPDU count.
  • Large of spanning tree topology changes notifications received on NNI links.

CP1 0x002105a2 09000004.65536 DYNAMIC SET GlobalRouter KHI WARNING VmSize of proc cbcp-main.x(4872) is 1604704KB, above 90% of available 1782579KB


CP1 0x000646b2 00000000 GlobalRouter MLT ERROR smltBulkMsgInit: can not allocate 22528 bytes
 

CP1 0x00270415 00000000 GlobalRouter SW ERROR Crash reporter data: Process Name: cbcp-main.x, Thread Name: tMainTask, Signal: 11, Slot:  1, PID: 4872, LWP: 5046
 

CP1 0x00270415 00000000 GlobalRouter SW ERROR Crash reporter data: [bt] Execution path
 

CP1 0x00270415 00000000 GlobalRouter SW ERROR Crash reporter data: [bt] /opt/appfs/lib/cp/libndlcs.so.1(_Z30nd_lcs_crash_exception_handleriP7siginfoPv+0x184) 
 

CP1 0x00270415 00000000 GlobalRouter SW ERROR Crash reporter data: [bt] cbcp-main.x(smltBulkSend+0x3a0) [0x106a06bc]
 

CP1 0x00270415 00000000 GlobalRouter SW ERROR Crash reporter data: [bt] cbcp-main.x(smltSendMsgs+0x970) [0x106a3c4c]


MSTP Cist port statistics on one such port noticed the thousands of incoming STP TC messages.

Port Number : 1/X
Cist Port Fwd Transitions : 1
Cist Port Rx MST BPDUs Count : 2670
Cist Port Rx RST BPDUs Count : 0
Cist Port Rx Config BPDUs Count : 0
Cist Port Rx TCN BPDUs Count : 0
Cist Port Rx TC BPDUs Count : 2003
Cist Port Tx MST BPDUs Count : 2673
Cist Port Tx RST BPDUs Count : 0
Cist Port Tx Config BPDUs Count : 0
Cist Port Tx TCN BPDUs Count : 0
Cist Port Invalid MSTP BPDUs Rx : 0
Cist Port Invalid RST BPDUs Rx : 0
Cist Port Invalid Config BPDUs Rx : 0
Cist Port Invalid TCN BPDUs Rx : 0
Cist Port Proto Migr Count : 0

 

Disabled the  device connected to port X/X brought the CPU under control and no further crashes were reported. Too many configuration TCN messages were sent from the VSP 8000, seen on multiple ports.

Port Number : 2/X
Cist Port Fwd Transitions : 1
Cist Port Rx MST BPDUs Count : 0
Cist Port Rx RST BPDUs Count : 0
Cist Port Rx Config BPDUs Count : 36179
Cist Port Rx TCN BPDUs Count : 0
Cist Port Rx TC BPDUs Count : 0
Cist Port Tx MST BPDUs Count : 5
Cist Port Tx RST BPDUs Count : 0
Cist Port Tx Config BPDUs Count : 0
Cist Port Tx TCN BPDUs Count : 804
Cist Port Invalid MSTP BPDUs Rx : 0
Cist Port Invalid RST BPDUs Rx : 0
Cist Port Invalid Config BPDUs Rx : 0
Cist Port Invalid TCN BPDUs Rx : 0
Cist Port Proto Migr Count : 1
 
Port Number : 2/X
Cist Port Fwd Transitions : 1
Cist Port Rx MST BPDUs Count : 0
Cist Port Rx RST BPDUs Count : 0
Cist Port Rx Config BPDUs Count : 2
Cist Port Rx TCN BPDUs Count : 0
Cist Port Rx TC BPDUs Count : 0
Cist Port Tx MST BPDUs Count : 4
Cist Port Tx RST BPDUs Count : 0
Cist Port Tx Config BPDUs Count : 35378
Cist Port Tx TCN BPDUs Count : 0
Cist Port Invalid MSTP BPDUs Rx : 0
Cist Port Invalid RST BPDUs Rx : 0
Cist Port Invalid Config BPDUs Rx : 0
Cist Port Invalid TCN BPDUs Rx : 0
Cist Port Proto Migr Count : 1
Environment
Virtual Service Platform 8000 is running software 5.1.1.2.
Cause
Produce is functioning as designed. Issue is due to improper configuration. STP Topology Change (TC) message flooding causes the MAC flush/re-learn on the switch which consumes system memory, causes high CPU which may lead to a potential system crash.
Resolution
  • It is advised to disable MSTP-0 instance on the switch to avoid VSP-8000 processing and sending TCN configuration messages.
#show spanning-tree config 
================================================================
                   Spanning Tree Config
================================================================
              BRIDGE  BRIDGE     FORWARD
ID   PRIORITY MAX_AGE HELLO_TIME DELAY   STATE
----------------------------------------------------------------
0    32768    20      0          15      Enabled
62   0        0       0          0       Disabled

 
  • MSTP-0 instance was enabled on NNI links as per the output below.When connecting the Avaya or non-Avaya device to VSP 8000 on non-SMLT/SPBM port, ensure to have a BPDU filtering.

spanning-tree bpdu-filtering [port <port>] enable [timeout <10-65535 | 0>]
Additional notes

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