Re: OT : BGP soft-reconfiguration inbound memory costs

>Does anybody have any experience with this feature?

On 12.4.x (something mainline I believe) I do. It does take up memory on a
720xVXR router with a NPE-G1 thats noticeable.

As Fabian was alluding to, it's only necessary when testing filters now that
BGP supports route-refresh so you don't have to keep a state table. There's
no other reason I can think of where you would need to apply it, so I only
use it on peers if I need to test filters.

-
m

On Sat, Feb 26, 2011 at 4:39 PM, eric_at_linux.ca <eric.lauriault_at_gmail.com>wrote:

> This is precisely what I thought too. I had 3 peers with full feed
> configured with the soft-reconfig inboud command. I figured I'd save on ram
> by removing it but couldn't see any difference afterwards...
>
> Full feeds were on 12.2(33)SXI. I labbed it up under 12.4(15)T.
>
> Does anybody have any experience with this feature?
>
> Eric
>
> On Sat, Feb 26, 2011 at 4:03 PM, Fabian Pucciarelli <fabiangp_at_gmail.com
> >wrote:
>
> > My understanding is that when you enable the feature you need enough RAM
> to
> > hold 2x the amount of nlri received from that neighbor. If you receive
> > internet full tables you would require a lot of memory, if it is a small
> > table you don't require much. I only use the feature to be able to use
> show
> > ip bgp neighbor x received and compare it to show ip bgp neighbor x
> routes
> > when testing inbound filters.
> >
> > F.
> > On Feb 25, 2011 2:22 PM, "eric_at_linux.ca" <eric.lauriault_at_gmail.com>
> wrote:
> > > Hi all,
> > >
> > > For a long time, word on the street was that "soft-reconfig inbound"
> > takes
> > > quite a bit of memory and is not as useful as it once was since most
> BGP
> > > implementations have added route refresh capabilities. I've also read
> > that
> > > "the code has been optimized and that the memory impact is
> insignificant
> > > nowdays". Kinda contradictory. I can't seem to find much information on
> > the
> > > exact cost in memory of this feature.
> > >
> > > For some time, we had this feature enabled on a few peers with full
> > feeds.
> > > One would think that by removing it, we would save quite a bit of ram.
> We
> > > didn't see any quantifiable difference in RAM usage.
> > >
> > > I've tried measuring the exact cost of this feature in a lab
> environment
> > but
> > > the following show commands weren't very helpful :
> > >
> > > show proc mem | i BGP : the bgp processes seem to take the exact same
> > amount
> > > of RAM
> > > show ip bgp sum : the memory and path/bestpath fields seems to be
> exactly
> > > the same, whether the command is there or not
> > > show ip bgp neigh : can't find anything there either
> > >
> > > Does anybody have any clear understanding of the memory costs of the
> > > "soft-reconfiguration inbound" command?
> > >
> > > Regards,
> > >
> > > Eric Lauriault, #27521
> > >
> > >
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Received on Sun Feb 27 2011 - 02:16:00 ART