AS announcement question (easy)
Hi, sorry for this low-level question, but at least I'm not posting in html. :) My company owns a class C, and we're switching ISPs. The "new" provider is telling us that they can start announcing, without us having to tell the old provider to stop announcing. I.e., a 2-3 day period where both are announcing our class C. This conflicts with my extremely (admittedly)limited knowledge. Can someone let me know if this is OK/not OK? Thanks in advance, Mike Michael Donahue WATG (949) 574-8500 x261
On Mon, 4 Aug 2003, Mike Donahue wrote:
My company owns a class C, and we're switching ISPs. The "new" provider is telling us that they can start announcing, without us having to tell the old provider to stop announcing. I.e., a 2-3 day period where both are announcing our class C.
This conflicts with my extremely (admittedly)limited knowledge. Can someone let me know if this is OK/not OK?
Originating the same prefix from two different ASes violates the RFC (or whatever bible you might pray to), but works most of the time. See "show ip bgp inconsistant-as" on cisco. YMMV. -- Mikael Abrahamsson email: swmike@swm.pp.se
Hi, NANOGers. ] See "show ip bgp inconsistant-as" on cisco. YMMV. On that theme, please also see: <http://www.cymru.com/BGP/incon01.html> <http://www.cymru.com/BGP/incon01-list.html> Thanks, Rob. -- Rob Thomas http://www.cymru.com ASSERT(coffee != empty);
On Mon, Aug 04, 2003 at 08:35:14PM +0200, Mikael Abrahamsson wrote:
On Mon, 4 Aug 2003, Mike Donahue wrote:
My company owns a class C, and we're switching ISPs. The "new" provider is telling us that they can start announcing, without us having to tell the old provider to stop announcing. I.e., a 2-3 day period where both are announcing our class C.
Inconsistant origins are bad. Which path is supposed to be believed? Which path is supposed to be selected? From what point of view? None of these are defined conditions; non-determinism is not good for performance. Expect some things to work, some things to be strange, and some to be lousy. Your best bet is to minimize the overlap period. Joe -- RSUC / GweepNet / Spunk / FnB / Usenix / SAGE
Hi, sorry for this low-level question, but at least I'm not posting in html. :)
My company owns a class C, and we're switching ISPs. The "new" provider is telling us that they can start announcing, without us having to tell the old provider to stop announcing. I.e., a 2-3 day period where both are announcing our class C.
This conflicts with my extremely (admittedly)limited knowledge. Can someone let me know if this is OK/not OK?
If you are going to have your link up to both providers during that time, it would not be a problem. However, if your /24 is nailed into the tables of your previous provider, and your link to that provider is down, then the old provider will create a blackhole for /24 for anyone who prefers the path presented by your old provider. In general, one really *should* coordinate switching between providers if ones' announcement is originated by the provider. Alex
Thanks in advance,
Mike
Michael Donahue WATG (949) 574-8500 x261
participants (5)
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alex＠yuriev.com -
Joe Provo -
Mikael Abrahamsson -
Mike Donahue -
Rob Thomas