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?
c6500#sh run | include system jumbo
system jumbomtu 9000
c6500#sh run int po 5
Current configuration : 224 bytes
description Channel xyz
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport mode trunk
logging event link-status
mls qos trust dscp
The concerned ports are on WS-X6724-SFP modules. Software Version is 12.2(33)SXI
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)
Cisco IOS Software, s72033_rp Software (s72033_rp-IPSERVICESK9-M), Version 12.2(33)SXI3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Tue 27-Oct-09 11:12 by prod_rel_team
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.
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
<1500-9216> MTU size in bytes
Try changing the MTU to 9216 and then try to check the same.
Do you mean I should go back to the default "system jumbomtu 9216" command?
I chose 9000 because the Catalyst 3560 connected to the 6500 support only 9000 bytes jumbo MTU and I wanted to stay consistent.
One has to say that the configuration ran fine for some weeks.
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.
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