Catalyst 6500 %CONTROLLER-SP-3-TOOBIG messages

Unanswered Question

Our logs are filling up with these messages from our c6500:

Apr 30 16:26:52: %CONTROLLER-SP-3-TOOBIG: An attempt made to send giant packet on Port-channel5 (1566 bytes from 82DD282, max allowed 1356)
-Traceback= 40AF0E00 40C9DC54 40814F74 4081B98C 4081A848 4081BAF0 40814A40 40813F94 40895A0C 408959F8

All logs are from Port-Channel interfaces, all these interfaces have an MTU of 9000 bytes (and the member interfaces are configured the same). So I really can't understand the message. Other than filling up the logs, I don't see any negative effects at the moment.

I can't find a reference to this message. Anyone else experienced this?


Mathias Rufer

Config extract:

c6500#sh run | include system jumbo
system jumbomtu 9000
c6500#sh run int po 5
Building configuration...

Current configuration : 224 bytes
interface Port-channel5
description Channel xyz
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport mode trunk
mtu 9000
logging event link-status
mls qos trust dscp

I have this problem too.
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francisco_1 Fri, 04/30/2010 - 08:03

what type of line card module is the port channel enabled on?

capture "show module" and "sh etherchannel summary"


The concerned ports are on WS-X6724-SFP modules. Software Version is 12.2(33)SXI

c6500#sh mod
Mod Ports Card Type                              Model
--- ----- -------------------------------------- ------------------
  2   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP
  3   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP
  5    2  Supervisor Engine 720 (Active)         WS-SUP720-BASE
  6    6  Firewall Module                        WS-SVC-FWM-1
  7   48  CEF720 48 port 10/100/1000mb Ethernet  WS-X6748-GE-TX

c6500#show etherchannel summary

Number of channel-groups in use: 6
Number of aggregators:           6

Group  Port-channel  Protocol    Ports
1      Po1(SU)          -        Gi2/24(P)      Gi3/24(P)
2      Po2(SU)          -        Gi2/23(P)      Gi3/23(P)
5      Po5(SU)          -        Gi2/15(P)      Gi3/15(P)
7      Po7(SU)          -        Gi2/3(P)       Gi3/2(P)
21     Po21(SU)         -        Gi7/17(P)      Gi7/18(P)

c6500#sh ver
Cisco IOS Software, s72033_rp Software (s72033_rp-IPSERVICESK9-M), Version 12.2(33)SXI3, RELEASE SOFTWARE (fc2)
Technical Support:
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Tue 27-Oct-09 11:12 by prod_rel_team


Mathias Rufer

francisco_1 Fri, 04/30/2010 - 08:19

maximum frame size of WS-X6748 SFP cards is 9216 bytes/frame. Can you try changing your MTU to 9216 and see if you get the same error.

rahurao Fri, 04/30/2010 - 08:10

Hi Mathias,

The default MTU size is 9216 bytes after you enable jumbo frame support on
the individual port. However, an Application Specific Integrated Circuit
(ASIC) limitation requires that you limit the MTU size to 8092 bytes on
these 10/100-based line cards:

Configure Native IOS

6500(config)#int gigabitEthernet 1/1
    6500(config-if)#mtu ?
      <1500-9216>  MTU size in bytes
6500(config-if)#mtu 9216

Try changing the MTU to 9216 and then try to check the same.


rahurao Fri, 04/30/2010 - 08:21

Hi Mathias,

I tried to check for the error message in association with the module which you are using and then the IOS version but it came up with nothing.

The only suggestion i would give is to enable the jubo frame support by enabling it to 9216 on the interface and then check.



francisco_1 Fri, 04/30/2010 - 08:25

Rahul, we are providing the same suggestion. I have also recommended he increased the mtu to 9216 for jumbo frame support and see what the outcome it..

Thank you both. I increased the global jumbo MTU to 9216. on the 6500, it's not possible to set the value invdividually for interfaces, so I had to change the global command which changed all the interface commands, too. Only inconvenience is that all Channels go down and up because the MTU doesn't match for an instant.

For now all seems OK - touch wood. Greetings

Mathias Rufer

rahurao Fri, 04/30/2010 - 11:42

Hi Mathias,

Thanks for the update and it really seems to be good news. Hope it works fine.




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