Junos
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Junos

BGP announcement priority

[ Edited ]
‎05-13-2019 04:59 PM

Hello,

 

when restarting our RE, it takes around ~30 Minutes for all (76) routes to be advertised to just one peer. The "top" cmd shows only ~140% of 400% CPU, is there any way to speed this up? I found "output-queue-priority" - is this the right thing to use?

 

I also watched the FIB summary and noticed that the announcements seem to start fast when all 750k routes (fulltable) are installed into the FIB, which are coming in via BGP peers.

 

Device: MX240

RE: RE-S-1800x4

Junos Version: 17.3R3.10

 

thanks before hand for any help!

 

regards,

Freemind

12 REPLIES 12
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Junos

Re: BGP announcement priority

‎05-17-2019 02:46 AM

Good day,

 

Could you please explain in details what did you do for "restarting our RE"? (Do you use "request system reboot"?)

Do you have second RE? If so, do you see that the line cards in the router also reboot?

Are we speaking about iBGP or EBGP ?

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Junos

Re: BGP announcement priority

‎05-23-2019 08:27 PM

its eBGP and we did a junos upgrade to the backup engine, then switched over (graceful switchover was not possible, thats why the whole bgpd restarts), linecard did not reboot

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Junos

Re: BGP announcement priority

‎05-25-2019 11:10 AM

Hi,

 

If swithcover was not gracefull then FPC must have rebooted. Do you know what was the time taken by BGP to advertise the routes once the BGP session was established ?

 

//Regards

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Junos

Re: BGP announcement priority

‎05-25-2019 02:45 PM

yes, around 20minutes. BGP was established very fast

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Junos

Re: BGP announcement priority

‎05-26-2019 07:08 AM

20 minutes seems excessive, especially if you are taking about advertising so few routes and only a change in peering not even a full reboot.

 

For a peer drop and restore on dual full internet routes I generally see advertisement of under 100 routes in less than a minute with the learning of two full tables around 5 minutes.

 

So it feels like some kind of configuration mesh for routes must be happening here beyond this single peering.  What is the full route learning architecture?  Are other protocols also enabled?  Are there multiple paths that have to be learned and balanced?  Passing of routes between protocols?

 

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
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Junos

Re: BGP announcement priority

‎05-29-2019 06:23 AM

no other protocols involved and we just do the usual prefix-list export. The BGP neighbor only has one export rule set, to export the prefix-list. Import is set to "then reject" on this neighbor.

 

The importing of other peers involves local-preference setting and that was it. No special protocols or config used, thats why I'm wondering its so slow in exporting(and not even using its full CPU power)

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Junos

Re: BGP announcement priority

‎05-30-2019 04:04 PM

How many other peers are involved to get the routes you export?

 

Wondering if the delay is that the routes that need to be exported are not active in the route table until learned from another peer.

 

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
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Junos

Re: BGP announcement priority

‎05-31-2019 09:36 AM

currently 71 of 75 routes affected are direct routes, assigned on the router itself, so they should be available right after boot I think

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Junos

Re: BGP announcement priority

‎06-01-2019 07:55 AM

Just trying to understand the full sequence here based on re-reading the notes.

 

The RE was rebooted (assume there is no second RE or no GRES / NSR based on comments)

This will reboot all the fpc after the RE comes up (how many are installed)

The BGP peer would not come up until that fpc and interface was up

The local routes will not come to the table until the interface is up (other fpc involved?)

Those routes should advertise withing a minute or two of coming active

 

So for a RE and single fpc I can see this taking 10-15 minutes.  Maybe an additional 5 minutes per additional fpc.

But it seems like you are seeing longer times than this.

 

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
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Junos

Re: BGP announcement priority

‎06-05-2019 07:56 PM

any idea how to analyze this further?

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Junos

Re: BGP announcement priority

‎06-06-2019 02:17 AM

Can you elaborate more on the below point that you made

 

"I also watched the FIB summary and noticed that the announcements seem to start fast when all 750k routes (fulltable) are installed into the FIB, which are coming in via BGP peers."

 

Are you suggesting that there are other BGP peers and a total of 750K routes are installed via these peers (after the reboot), and the 75 routes are advertised to the ebgp peer only after these 750K routes are installed? 

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Junos

Re: BGP announcement priority

‎06-06-2019 06:15 AM

"Are you suggesting that there are other BGP peers and a total of 750K routes are installed via these peers (after the reboot), and the 75 routes are advertised to the ebgp peer only after these 750K routes are installed?"

 

yes, exactly. thats what its looked like to me

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