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Community Member

6513 port-channels fail on high throughput...

I'm having a problem with port-channels failing between two 6513 chassis with sup 720s and the 6724-SFP line cards in high throughput situations. The IOS is 12.2(18)SFX5. Has anyone else ever encountered such issues? If so, what was the resoution. Thanks! Dennis.


Re: 6513 port-channels fail on high throughput...

could be something like this.

CSCeg49196 Bug Details

Headline Excessive Overruns and lbusDrops due heavy flow control over fabric

Product IOS

Feature OTHERS Components Duplicate of

Severity 1 Severity help Status Resolved Status help

First Found-in Version 12.2(17d)SXB02 All affected versions First Fixed-in Version 8.5(0.21)JAC, 8.4(1.19), 8.6(0.51)TAL, 8.4(1.21), 12.2(17d)SXB07, 8.4(1.43), 8.4(1.45), 8.5(0.44)JAC, 8.6(0.69)TAL, 8.4(0.61)RCC05, 12.2(18)SXD04 Version help

Release Notes

A Sup720 system where the majority of modules are of type WS-X67xx may

experience system traffic flow degradation under certain traffic profiles,

typically meshed communication among hosts connected to all modules in the

system plus many-to-one type of communications. The symptoms seen during this

condition include:

- overruns on almost all active interfaces

- lbusDrops associated with the supervisor slot (seen via "show fabric channel-


- TestMacNotification test failed messages seen repeatedly via "show log" for

modules with DFC's installed

- ports leaving and re-joining an EtherChannel

- Routing protocol flaps (hsrp, ospf ...)

- line protocol for multiple interfaces going down

Typically the time interval between occurrences of the problem fluctuates

greatly. During the problem overall PPS (packets-per-second) performance is

drastically reduced through the system as seen via the "show mls statistics"



Reduce the amount of traffic flowing through the switch, particularity on

interfaces seeing the most overruns.

Community Member

Re: 6513 port-channels fail on high throughput...

Thanks Grant. The issue has to do with system backups across the core causing the port-channels to fail, so this is definitely on the right track. It affects the 6724 and 6748 modules.

This was helpful! Thanks again.


Community Member

Re: 6513 port-channels fail on high throughput...

CSCeg49196 Bug Details states it was 'First Fixed-in Version .... 12.2(18)SXD04, but Dennis' version is 12.2(18)SXF5.

Does that mean Dennis' problem may be related to something else?


Re: 6513 port-channels fail on high throughput...

SXF is a different train than sxd, if you look at the affected versions of this problem his IOS version was on the affected list so its possible it could affect him .

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