About route aggregation

[Balkov V. P.]

Dear Gated-people !

I have one problem: our service provider announce not aggregated
routing via BGP-4 (it is not natural case but *ce la vi*). My
gated_R3_5Beta_3 don't allow to aggregate this routing on our side and
remove contributing route from routing table.

In my opinion, it was can to do:

1. Supress contributing route installation in routing table
(and announce it) by *import...restrict* statement.
2. Include *generate* statement with correspondance
preference value and with *import...restrict*'ed routes as
contributing routes. But this version gated (and other, I think)
determine preference of aggregated (and generated) route as lowest
preference of contributing routes (-1 in this case) and ignore any
preference clause in *generate* statement.

Is any possibilities resolve my problem ?
Is this case unique or not ?

---

Vladimir Balkov,
OKB MEI
Phone: +7 095 362 7502
Fax: +7 095 362 5576

[Acee Lindem]

"Balkov V. P." <BAL...@okbmei.msk.su> writes:

> I have one problem: our service provider announce not aggregated
> routing via BGP-4 (it is not natural case but *ce la vi*). My
> gated_R3_5Beta_3 don't allow to aggregate this routing on our side and
> remove contributing route from routing table.
>
> In my opinion, it was can to do:
>
> 1. Supress contributing route installation in routing table
> (and announce it) by *import...restrict* statement.
> 2. Include *generate* statement with correspondance
> preference value and with *import...restrict*'ed routes as
> contributing routes. But this version gated (and other, I think)
> determine preference of aggregated (and generated) route as lowest
> preference of contributing routes (-1 in this case) and ignore any
> preference clause in *generate* statement.
>

Vladimir,

This really isn't the way "generate" was meant to be used. In this situation,
the normal thing to do would be to use "aggregate" to define an aggregate
route and export it into your IGP. This would not reduce the number routes
on the system talking to your ISP but it would reduce the number injected
into your routing domain.

The BGP routes which are restricted are kept in the GateD routing table so
that policy can be changed dynamically. They are not meant to be interpreted
as contributing routes for "generate" or "aggregate". Hence, the only way
to do what you want (or about to what you want) would be to allow one
more of the routes to be installed. The best route(s) to pick are the
one within the range which are most likely to be available. However, if
you're going to do this than why not just keep all the BGP routes
restricted and define a static route.

Acee