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Import/Export priority

[ Edited ]
‎03-25-2019 06:12 PM

Hello,

 

problem on our MX240 after a restart is that the imports and exports of routes seem to be load balanced, thus we have 300k routes in our table, but only a few routes are advertised after minutes. I found "priority" for importing routes, but is there a way to priorize export routes first and then start importing?

 

Currently we edit the config to stop imports and after all exports are done, we enable the imports again. Exports should come first, because we have a default route set for outbound traffic.

 

Thanks in advance for any help 🙂

 

regards,

Freemind

1 REPLY 1
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Re: Import/Export priority

‎03-26-2019 12:43 AM

Hello,

 


@Freemind wrote:

Hello,

 

problem on our MX240 after a restart is that the imports and exports of routes seem to be load balanced, thus we have 300k routes in our table, but only a few routes are advertised after minutes.


 

This is actually a good thing that MX240 does not attract traffic when programming of the routes in the FIB is not finished yet. You may want to make it deterministic either with event-policy (triggering event is SYSTEM_OPERATIONAL + configurable delay, works with any routing protocol), or use "delay-route-advertisements" knob (specific to BGP) 

https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/delay-rou...

 

 


@Freemind wrote:

I found "priority" for importing routes, but is there a way to priorize export routes first and then start importing?

 

 


 

Not supported, although  You can automate this to an extent using event-policy and/or script as I mentioned  above.

But generally speaking, You don't want to export anything until FIB is programmed. Assuming You export statics+aggregates+maybe generates,  this can lead to a blackhole in certain situations - when, for instance, You have a summary static discard but rely on specific BGP routes to actually route traffic out.

 


@Freemind wrote:

 

Currently we edit the config to stop imports and after all exports are done, we enable the imports again. Exports should come first, because we have a default route set for outbound traffic.

 

When route export and import are running concurrently, exporting 0/0  and/or ::/0 first does not guarantee that it is programmed in the FIB first. So, You need to keep imports disabled to guarantee that exports are processed first.

There was a forum thread a while ago to solve a similar problem, and the solution can be adapted to suit Your needs

 

https://forums.juniper.net/t5/Junos/Event-option-after-5-minutes/m-p/459785/highlight/true#M14388

 

HTH

Thx

Alex

 

 

 

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