On Wed, Oct 13, 2004 at 12:54:44PM -0700, Kevin Oberman wrote: > > Date: Wed, 13 Oct 2004 18:43:45 +0000 > > From: [EMAIL PROTECTED] > > Sender: [EMAIL PROTECTED] > > > > > > > > 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.
good traditional thinking .... requireing me to announce the whole /20 when all i'm using is a /27... after all, its just one routeing table entry... why should you care? :) (playing straightman) > 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. so -IF- everyone followed your internal address assignment policies, scattering used space in a sparse matrix throughout the allocated pool, then announing a single prefix (the aggregate) makes sense. Of course this leaves you w/ lots of space that is useful for forging as valid source addresses. (we'll even leave DHCP pools out of the discussion - for now) so it would make sense for you to announce the aggregate - since you use "random" bits throughout (nice marbling!) but for those folks who use a more compact internal representation, is there a good reason to reject their /27 instead of the larger /20 that has been allocated? > > thanks for letting me rant. :) > > Any time, Bill. I'll try and use it wisely --bill