[c-nsp] Growing BGP tables

[Jon Lewis]

On Fri, 28 Jan 2005, Joe Maimon wrote:

> >That's incredible.  I can't believe that so few people would see the
> >benefit in this.  I know one of those attachments was mine.

> This is something discussed a while back, how to deal with those who
> insert more specifics, right?
> This was also mentioned as neccessary to avoid the loophole in Team
> Cymru bogons, correct?

I think these are two similar but very separate issues being talked about
together, when maybe they shouldn't.

In the bogons case, I'd love to be able to take a bogon feed from a
trusted source (i.e. team cymru) and have those routes put in the table as
"special poison routes".  I don't ever want another peer to be able to
advertise any of those routes or more specifics, and if they do, I want to
ignore those routes.  The same logic could be applied to abusive networks
you don't want to exchange traffic with.

The more general issue of ignoring more specifics for those who announce
CIDRs and subnets of them for no obvious (or operational to me) reason is
far more complicated as ideally you'd like the previously ignored more
specifics to magically resurface if the aggregate route disappears.

If we treat these as separate issues/features, would it be that hard to
have a route-map match statement in the very near future that could check
incoming routes against a certain set of routes (perhaps by the next hop
IP of the already installed routes) and reject them based on that?

i.e.
Assume I have a feed of bogon routes and have their next-hop IP set to
192.0.2.1.

route-map blah-input deny 10
 match existing-next-hop 192.0.2.1
route-map blah-input permit 20
....

That doesn't seem like it'd be rocket science to implement...but then I've
never seen cisco's BGP code.

----------------------------------------------------------------------
 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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