Re: [GROW] draft-iops-grow-bgp-session-culling-00

[Job Snijders <[e-mail]>]

On Tue, Mar 14, 2017 at 02:28:56PM +0000, [e-mail] wrote:
> > From: GROW [mailto:[e-mail]] On Behalf Of heasley
> > 
>  > Mon, Mar 13, 2017 at 02:07:21AM +0100, Alejandro Acosta:
>  > > What do you think in including also some suggestions when bringing up
>  > > the BGP sessions?.  Sometimes it´s good idea to bring them up one by one
>  > > or something like that, the idea is to make the device to fill out the
>  > > forwarding table, create cache, perform ARP lookups, ND, and so on. To
>  > > bring up all the session at once many times is not that good.
>  > 
>  > I'd expect this to prolong and exacerbate the 'path hunting', while the
>  > min-advert-timer might help to squelch it if all sessions are enabled
>  > at the same time - after the IGP settles, which is automatic in some
>  > impl..
>  > 
>  > randy, link to path hunting paper?  i can't seem to find it.
> 
> For the BGP shut, in section 2.1. " Voluntary BGP Session Teardown
> Recommendations" you could propose or at least reference BGP Graceful
> shutdown https://tools.ietf.org/html/draft-ietf-grow-bgp-gshut-06
> In very short, it initiates the path hunting for the backup BGP path,
> _before_ the withdraw of the nominal path. Tests have shown that 0
> packet loss is achievable (assuming that within the AS, tunneling is
> used in order to avoid micro-loops during iBGP convergence). But if
> one is not targeting 0 packet loss, which is typically the case in the
> Internet ecosystem, there is no requirement for tunneling.
>
> In short, over eBGP, routes to be withdrawned are tagged with a "well
> known" community, in order to be de-preferred on the receiving side.
> 
> Some vendors have automated this. But one may also do it manually
> using BGP policies.

I appreciate the effort and thought that has gone into gshut, but I am
not aware of actual deployments and as scuh certainly cannot vouch for
using this method as a 'best current practise'. it may be a 'future best
practise' - but that is not now.

Kind regards,

Job