aggregation & table entries

Kevin Oberman oberman at
Wed Oct 13 19:54:44 UTC 2004

> Date: Wed, 13 Oct 2004 18:43:45 +0000
> From: bmanning at
> Sender: owner-nanog at
> > > 	or... why do people insist on injecting routes to non-existent
> > > 	things?    a route table entry is a route table entry, regardless
> > > 	of the scope.  
> > 
> > Is this where you advocate that providers only announce the parts of
> > their assigned blocks that are in use?
> 	seems like a good lead in, so yes - i advocate folks only
> 	announce what they use.  may play old-hob on the ISP that
> 	likes to use some other metric for accepting announcements,
> 	(e.g. RIR or other routing registry DB) and will no doubt
> 	increase the tension on justification of proxy announcements,
> 	but overall, this seems to be a good goal.

First, we do accept prefixes from most ASes based on RIR.

Second, we don't simply assign address space sequentially from our
assigned spaces. We have an addressing plan that leaves the assignments
deliberately sparse to allow for better management and the ability to
keep our PA assignments to a site contiguous. To only announce the
active space would increase the number of routes we announce by about
80%. If everyone did this, the routing table would increase
massively. So would the time to compute the routes which might lead to
some really bad instability for some routers.

> 	thanks for letting me rant. :)

Any time, Bill.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at			Phone: +1 510 486-8634

More information about the NANOG mailing list