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>, 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.


> 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...


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