[AusNOG] BGP hold timer values

[Tom Berryman]

There is a bit more than just a few extra packets (as your cost) - BGP can/does have notable CPU impact on low-mid range routing gear.

With eBGP, you are talking propagation of your routes to the internet, so not all of the internet is going to see your changes for maybe up to 180 seconds. That said, it's likely most of it will be sooner than that.

Tom





On 27 Jan 2015, at 11:01 pm, Alex Samad - Yieldbroker <Alex.Samad at yieldbroker.com<mailto:Alex.Samad at yieldbroker.com>> wrote:

Hi

Okay its eBGP, currently have 4 providers, some with multiple connections. So I am thinking 6 / 20 might be good for me, business requirement for approx. 30sec response.
I am presuming all I am looking at is extra BGP packets .. every 6 sec compared to 1 min..


Alex

-----Original Message-----
From: David Hughes [mailto:david at hughes.com.au]
Sent: Tuesday, 27 January 2015 9:37 PM
To: Alex Samad - Yieldbroker
Cc: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
Subject: Re: [AusNOG] BGP hold timer values


I gave a lightning talk about this sort of thing a while ago at an APRICOT.  I just
googled to find the slides and can now see just how many years ago it was.
Gotta say I'm feeling old :)

But, it's probably still relevant although the defaults may have changed.  This
reflected what we were running at the time - and we were trying to be
pretty aggressive.

http://archive.apnic.net/meetings/21/docs/sigs/routing/routing-
pres-hughes-bgp.pdf

For reference I'm currently happy to run

eBGP : 10 / 30
iBGP : 5 / 15

And I'd run this even to a single upstream.  If it fails at least you'll have
something in your logs to say why you fell off the net for a while.  Silent
failures are a bugger to troubleshoot.


Thanks

David
...



On 27/01/2015, at 6:47 PM, Alex Samad - Yieldbroker
<Alex.Samad at yieldbroker.com> wrote:

Hi

I'm wonder what is considered "best practice" or good/responsible hold
timer values for BGP.

Currently I'm set at 3m, but I am considering lowering this to 30s and keep
alive down to 20s, potentially even lower. Or if possible to use BFD & BGP,
what's the uptake on BFD ?

Alex
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