BGP vs. static routing (Re: Why Vadim likes statics)
bmanning at ISI.EDU
bmanning at ISI.EDU
Tue Apr 25 14:25:25 UTC 1995
>
>
> In message <199504241414.AA14108 at zed.isi.edu>, bmanning at ISI.EDU writes:
>
> | This sounds a lot like the slippery slope of static routing being the most
> | stable, so we should encourage its use Internet wide. I -know- Karl D.
> | (and others that depend on dynamic routing for alternate provider fallback)
> | will kick at this.
>
> Why? What we have been arguing for has been limiting
> the scope of dynamic routing only to places where
> participating in global dynamic routing makes sense.
So it does not make sense for IBM or Sony to run dynamic routing
in their internal networks?!?
> The border router does aggregation outbound and points the
> aggregates at Null 0 with a high metric.
True.
> This is for cases in which there is no other router
> participating within the customer iBGP mesh, and where there
> are N (N>=1) upstream providers, and where dynamic routing
> must take place within the ISP's routing domain for various
> reasons (portable dialup links, links that are time-sensitive, etc.)
The assumption in this case is a common egress point.
> The iBGP box should do aggregation and have static routes
> pointing to Null0 for all nets it announces to the two edge
> routers.
Again, a common egress point is assumed and to differeniate
policy by provider will involve netlists.
> A more complex case is one like this:
>
> Provider X Provider Y Peers A, B, Z
> | | |
> +--------+ +--------+ +---------+
> | | | | | |
> +--------+ +--------+ +---------+
> \ | /
> (a bunch of iBGP-talking routers)
>
> at this point people are building something akin to what
> NSPs do.
> ..............
> Step 2 is to do the _same_ aggregation and high-metric
> routing to Null 0 on all the border boxes (the three shown
> above) so that a consistent picture of this small-i internet
> is presented to the outsides world.
The assumption here is that there is a consistant policy
from this ISP to all its peers. This may not be true.
(I am working at a site which is an existance proof)
> I'd detail several more steps but my fingers tell me they
> want to go on to the next message.
No problem...
--bill
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