CNaaS configuration templates

Explanations of parts of the configuration templates for CNaaS

Storm control

The default template includes storm control configuration for edge ports in most cases, the configuration looks like:

storm-control broadcast level 7

This means if the amount of broadcast reaches 7% of the interface bandwidth storm control will trigger. Depending on how storm-control is configured it will either block the specified traffic type (broadcast in this case) or disable the interface by putting it in errdisable state.

If this configuration is applied the interface will be put in errdisable:

errdisable detect cause storm-control
errdisable recovery cause storm-control

If there is a L2 loop in the network putting the interface in errdisable should stop the loop and prevent major network outages.

Here is example output of show storm-control on an interface where errdisable is not enabled:

a1#show storm-control ethernet 26 
Port Type      CPU Level Units Rate(Mbps) Status  DropPkts DropOctets Reason Errdisabled
---- --------- --- ----- ----- ---------- ------ --------- ---------- ------ -----------
Et26 broadcast no  7.0   %            700 active 110465159          0        no         

The drop counter increases but the interface is never put in errdisabled state. For EOS <4.33 there will be no log messages about this.

If errdisable detect has been enabled this will be the output of show storm-control:

a1#show storm-control ethernet 26
Port Type      CPU Level Units Rate(Mbps) Status  DropPkts DropOctets Reason Errdisabled
---- --------- --- ----- ----- ---------- ------ --------- ---------- ------ -----------
Et26 broadcast no  7.0   %            700 active 811502221          0        yes        

To check the errdisable status:

a1#show interfaces status errdisabled
   Port       Name                     Status         Reason       
---------- ------------------------ ----------------- -------------
   Et26       ixia-switch port15       errdisabled    storm-control

a1#show errdisable recovery 
   Errdisable Reason              Timer Status   Timer Interval
------------------------------ ----------------- --------------
...
   storm-control                  Enabled                   300

Interfaces that will be enabled at the next timeout:
   Interface        Errdisable reason    Time left(sec)
---------------- ----------------------- --------------
   Ethernet26       storm-control        95            

If errdisable triggers then there will be a log message even in EOS <4.33 , like this:

Nov 28 10:10:03 a1 Ebra: %ETH-4-ERRDISABLE: storm-control error detected on Ethernet26.