Storm control blocking

[afsharki2]

Hello, A week ago, i got a storm control log message:

SwitchA:

 %STORM_CONTROL-3-FILTERED: A Broadcast storm detected on Te1/1/1. A packet filter action has been applied on the interface.

show storm control:

Te1/1/1   Blocking       Enabled   Disabled    5.00%   

I subsequently look on the other side of the link to SwitchB:

SwitchB:

Te1/1/2   Blocking       Enabled   Disabled    5.00%

My question is, how do i unblock this and why has it stayed block for over a week now, with only 1 log message generated?

Thank you

[paul driver]

Hello

Sounds like storm control was enabled but errorrecovery pertaining to storm control was left disabled, which is the default.

sh storm-control broadcast | multicast | unicast
sh errdisable recovery
or

sh errdisable recovery | in storm-control
( you will see all storm control feature disabled)

To enable error recovery for storm control

conf t

errdisable recovery cause storm-control
errdisable recovery interval xx
 

sh errdisable recovery | in storm-control
storm-control                Enabled

Lasty you can set what action to perform if a storm control level is exceeded on the interface
int x/x
storm-control action shutdown | trap

res

Paul

[Madhukrishnan Gopinathan Nair]

Hello,

Paul has already explained in detail, but for the moment to bring it up, you can do a shut/no shut on the interface. But please follow Paul's recommendation so that once it is down, it will automatically recover it from the condition.

Regards.

Madhu

[afsharki2]

I will do a shut no shut, since its a port channel

[amikat]

Hi,

As you have configured "storm-control action trap" there is absolutely no point to think of errdisable issue. The command specifies that in addition to traffic filtering the trap is also send.

The storm control mechanism differs slightly as for the various models. You have not clearly indicated what your box is, I guess it may be Cat4500 series. If so than the broadcast supression (your case) is done over a one-second interval and when the threshold is reached it filters out the subsequent broadcast packets. So that is why you can see some broadcast going through (up to 5% for each interval). My view is that since the excessive broadcast started (a week ago ?) the mechanism is filtering continuously within every interval and that is why you can see "Blocking" all the time. Also if this is the case you can see only 1 error log message (more messages would be generated only if there is at least one interval without supression followed again by the supression).

Finally you can disable the storm control (ie. unblock) via the "no storm-control broadcast level 5.00" or "storm-control broadcast level 100.00" interface command.

Best regards,

Antonin

[afsharki2]

Thanks Paul!  I looked at the err recovery and it is already set on "enabled" for storm control.  Why do you think it's still set on "Blocking"?

ErrDisable Reason            Timer Status

storm-control                Enabled

Just to let you know this is a 4 port port-channel and 2 of the interfaces are in blocking mode

I actually did a counter lookup and the interfaces seem to be passing traffic...not sure what's going on.  The interface claims to be in blocking mode from Storm control, but it's passing all traffic(unicast, multicast and broadcast ..both ways)

This is the config on the etherchannel:

 storm-control broadcast level 5.00
 storm-control action trap