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Beginner

ISIS Protocol Dampening

A hopefully simple question but I can't find much documentation on how to do it.  Is there a way to dampen the neighbor adjacency of ISIS?  I know there is interface dampening but I am not referencing that.  I am referring to scenarios where the adjacency flaps a lot but the interface stays up.  Is there a slow restart setting or a way to dampen when it bounces enough times?

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Beginner

Re: ISIS Protocol Dampening

I have been looking for the same. Huawei med/high end switches and routers do support  the interface level config of "isis peer hold-max-cost timer".

 

Usage Guidelines
When a Down IS-IS interface goes Up, IS-IS neighbor relationships are re-established on the interface, and traffic is switched back to this Up interface after IGP route convergence. IGP route convergence is fast, but many services that depend on IGP routes may not expect such fast traffic switchback. To delay traffic switchback after IGP route convergence, run the isis peer hold-max-cost command to set the maximum holdtime for the largest IS-IS route cost (16777214 in wide mode and 63 in narrow mode) in local LSPs. In this manner, before the specified maximum holdtime expires, traffic is not switched back to this route due to its large cost. After the specified maximum holdtime expires, the route cost reverts to the original value, and then traffic is switched back to this route.

NOTE:
The effective time of the specified maximum holdtime is different for P2P and broadcast neighbors.

•For a P2P neighbor, the maximum holdtime takes effect after the neighbor relationship goes Up.
•For a broadcast neighbor, the maximum holdtime takes effect after the neighbor relationship goes Up and then a DIS is elected successfully.
Example
# Set the maximum holdtime to 1000 ms for the largest IS-IS route cost in local LSPs on 10GE1/0/1.

 

<HUAWEI> system-view
[~HUAWEI] isis
[*HUAWEI-isis-1] network-entity 01.0000.0000.0001.00
[*HUAWEI-isis-1] quit
[*HUAWEI] interface 10ge 1/0/1
[*HUAWEI-10GE1/0/1] undo portswitch
[*HUAWEI-10GE1/0/1] isis enable 1
[*HUAWEI-10GE1/0/1] isis peer hold-max-cost timer 1000

 

The value is in milliseconds, the example config is from CE12800 series DC switch.

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Hall of Fame Expert

Re: ISIS Protocol Dampening

Hello crench92,

if your device support it use BFD to detect flapping links

 

Hope to help

Giuseppe

 

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