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CSCvk32439 - IPv6 - SISF main thread consumes high CPU DHCPv6/ICMPv6 SOLICIT - 2

kcrane2
Level 1
Level 1

I believe that this bug, or a variation of it, is present in 16.3.7 as well.  We have been fighting a high CPU issue with SISF switcher since upgrading to 16.3.7 as well and initially applied this to just the trunk links as described.  After a number of attempts to resolve this issue failed and even splitting the stack into 2 smaller stacks failed we put the IPv6 filer into the user interfaces and this stopped the issue immediately.  We could not identify any clear signs that there was a "flood" of traffic going on.

 

Prior to applying the filter to the switch ports:

 

switch#sh proc cpu sorted 
CPU utilization for five seconds: 95%/38%; one minute: 94%; five minutes: 94%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process 
299 16210718 412251 39322 48.85% 45.78% 45.60% 0 SISF Switcher Th 
225 949559 115216 8241 2.06% 1.73% 1.73% 0 Spanning Tree 

This was applied to each bank of ports:

switch(config-if-range)#ipv6 traffic-filter DENY-IPV6 in 
switch(config-if-range)#int range g2/0/1-48       

CPU usage afterwards:

switch#sh proc cpu sorted
CPU utilization for five seconds: 18%/5%; one minute: 34%; five minutes: 73%
 PID Runtime(ms)     Invoked      uSecs   5Sec   1Min   5Min TTY Process 
 225      959669      116139       8263  1.91%  1.76%  1.76%   0 Spanning Tree    
  74     1581721      536829       2946  1.75%  3.13%  3.14%   0 IOSD ipc task    

 

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