[c-nsp] BGP DFZ convergence time - FIB programming

[Mark Tinka]

On 12/Oct/18 14:12, adamv0025 at netconsultings.com wrote:

> There are several possible attach-points that can be used to manipulate the
> iBGP route before it gets installed into RIB, (ibgp session/vrf
> import/BGP->RIB)
> Now would you say all of these are sort of in the inbound direction from the
> iBGP perspective? After all the iBGP route would be subject to all these
> before it gets installed to RIB. 

We generally apply quite a bit of policy at the eBGP edge, i.e., with
customers, peers or upstreams. Once those policies are applied, we just
pass them as they are toward the RR's via iBGP, not touching them again.

The policy we would apply on the edge device itself that is not part of
an eBGP session would be locally-generated routes, e.g., routes that
define all point-to-point addresses used for customers attached to that
device, peers attached to that device where we are providing the
point-to-point IP addresses, e.t.c.

Then on the RR's, we can determine whether we want those routes to be
seen by the entire network, or some section of the network, based on the
BGP communities that the route arrives with at the RR. This is
influenced by the type of service the route is carrying, be it a
customer or another internal function.

Mark.