High CPU when tranferring data between VLANs on the same subinterface

[peter.jevos]

Hi 

i have Cisco 2821 with 2 subinterfaces on the G0/0, with 2 different VLANs on them.

When i copy about 60 Mb/s between them, the CPU usage increase to 80-90 %, and start to drop the packets.

The CEF is on on all those subinterfaces.

Any recommendations ? 

many thanks

Here is the info about those subinterfaces:

#sh cef interface g0/0.10
GigabitEthernet0/0.10 is up (if_number 5)
  Corresponding hwidb fast_if_number 21
  Corresponding hwidb firstsw->if_number 2
  ICMP redirects are always sent
  Per packet load-sharing is disabled
  IP unicast RPF check is disabled
  Input features: Stateful Inspection, Virtual Fragment Reassembly, Virtual Fragment Reassembly After
  Output features: Stateful Inspection, TCP Adjust MSS
  IP policy routing is disabled
  BGP based policy accounting on input is disabled
  BGP based policy accounting on output is disabled
  Hardware idb is GigabitEthernet0/0
  Fast switching type 1, interface type 27
  IP CEF switching enabled
  IP CEF switching turbo vector
  IP prefix lookup IPv4 mtrie 8-8-8-8 optimized
  Input fast flags 0x400061, Output fast flags 0x10181
  ifindex 2(2)
  Slot  Slot unit 0 VC -1
  IP MTU 1500

#sh cef interface g0/0.117
GigabitEthernet0/0.117 is up (if_number 21)
  Corresponding hwidb fast_if_number 5
  Corresponding hwidb firstsw->if_number 2
  ICMP redirects are always sent
  Per packet load-sharing is disabled
  IP unicast RPF check is disabled
  Input features: Stateful Inspection, Virtual Fragment Reassembly, Virtual Fragment Reassembly After
  Output features: Stateful Inspection
  IP policy routing is disabled
  BGP based policy accounting on input is disabled
  BGP based policy accounting on output is disabled
  Hardware idb is GigabitEthernet0/0
  Fast switching type 1, interface type 27
  IP CEF switching enabled
  IP CEF switching turbo vector
  IP prefix lookup IPv4 mtrie 8-8-8-8 optimized
  Input fast flags 0x400061, Output fast flags 0x10181
  ifindex 2(2)
  Slot  Slot unit 0 VC -1
  IP MTU 1500

sh int g0/0 st
GigabitEthernet0/0
          Switching path    Pkts In   Chars In   Pkts Out  Chars Out
               Processor   13584490  436643191   27043759 2436202283
             Route cache   70111252 1482061430   60433310  610254739
                   Total   83695742 1918704621   87477069 3046457022

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Recommendation?  Yes, you may need a faster router.  At 60 Mbps, you might be bumping into the capacity limitations of the 2821.

[peter.jevos]

Hi Joseph

thanks for your answer. Are you sure we reached the switching limit on the 2821 ?

Pet

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

In my posting, I pasted a snapshot of the 2821's performance.  However, it's not showing publicly, so try this link: http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf