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RE: BGP Filtering
Hi, Default wont work - I do care about my transit providers network becoming partitioned or IXPs having problems or fiber cuts etc etc So I need my router to see all the reachability of a prefix in BGP so that my router knows which transit to send it to. Defaults wont work because a routing decision has to be made, my transit originating a default or me pointing a default at them does not guarantee the reachability of all prefixes.. But if I can see the /19 in the table, do I care about a load of /24s because the whole of the /19 should be reachable as the origin AS is announcing it somewhere in their network and it is being received my a transit so should be reachable. Ok, I can dream up a few emergencies where it might be helpful to pin a /24 as well as the /19 - but I am sure there aren't 100K+ emergencies happening continuously in the route table and it is on the whole general whatever because there is no incentive to stop de-aggregating once you have started. If they are only announcing the de-aggregated /24s and no summary /19 then my question doesn't apply as I only want to drop the more specifics where a less specific exists. I am struggling to see a defensible position for why just shy of 50% of all routes appears to be mostly comprised of de-aggregated routes when aggregation is one of the aims RIRs make the LIRs strive to achieve. If we cant clean the mess up because there is no incentive than cant I simply ignore the duplicates. Regards Ben -----Original Message----- From: Jared Mauch [mailto:jared@xxxxxxxxxxxxxxx] Sent: 15 January 2008 16:19 To: Ben Butler Cc: nanog@xxxxxxxxx Subject: Re: BGP Filtering On Tue, Jan 15, 2008 at 04:11:36PM -0000, Ben Butler wrote: > As a transit consumer - why would I want to carry all this cr*p in my > routing table, I would still be getting a BGP route to the larger > prefix anyway - let my transit feeds sort out which route they use & > traffic engineering. Well, you could always just take "Customer" routes from each of your providers (since you're running BGP I presume you're actually multihomed and not adding to the pollution) and point default at one/both providers for the other networks (or take default from one or both of them). - jared -- Jared Mauch | pgp key available via finger from jared@xxxxxxxxxxxxxxx clue++; | http://puck.nether.net/~jared/ My statements are only mine.