[c-nsp] full routing table / provider-class chassis

[Ian MacKinnon]

Thanks Gert, excellent answer.

> -----Original Message-----
> From: Gert Doering [mailto:gert at greenie.muc.de]
> Sent: 11 June 2009 16:17
> To: Ian MacKinnon
> Cc: Gert Doering; Jo Rhett; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] full routing table / provider-class chassis
>
> Hi,
>
> On Thu, Jun 11, 2009 at 03:57:11PM +0100, Ian MacKinnon wrote:
> > > "XL" or "non-XL" has nothing to do with the number of *peers*.
> > >
> > > "XL" decides on the number of prefixes that you can have in your
> > > forwarding table (hardware FIB) - and this will be about the same
> > > for
> > > "1 peer with a full BGP Table" or "20 peers with the same set of
> > > prefixes but just different BGP paths".
> > >
> > > A higher number of different "full table "peers is going to eat up
> > > CPU memory and CPU power - memory is easy (Sup720-3CXL comes with
> > > 1Gbyte RAM, which is sufficient for at least 10 "full table" BGP
> > > peers), but CPU might reach its limit with 5 full table peers and
> 91 others.
> >
> > I was the under the impression that the limit on these boxes (and
> > ASR1002 R1) was approx 1 Million routes.
>
> True.  *FIB space* routes.
>
> > I had assumed that was the total number of routes from all your
> peers,
> > eg we see about 280k routes in a full table,
>
> Correct.
>
> > so that would be approx 4 full tables.
>
> No.
>
> 1 full table has 280k routes.
>
> 100 full tables have 280k routes as well. (But LOTS of additional BGP
> path information - but those are not stored in the FIB, and don't count
> for the "1 million" limit).
>
> > Are you saying that the limit on the number of routes, is actually in
> > the FIB, ie active routes, so currently would always be about 280k,
> > and multiple full tables is OK.
>
> BGP paths that don't go to the FIB are not "routes".  They are just
> prefixes with path info.
>
> (In other words: yes).
>
> gert
> --
> USENET is *not* the non-clickable part of WWW!
>
> //www.muc.de/~gert/
> Gert Doering - Munich, Germany
> gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-
> muenchen.de

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