nanog mailing list archives
Re: Failover solution using BGP
From: Malte von dem Hagen <mvh () hosteurope de>
Date: Wed, 31 Dec 2008 02:49:04 +0100
Hi, Am 31.12.2008 01:19 Uhr, Braun, Mike schrieb:
Why not just AS prepend your secondary site if the services to the Internet are the same at both sites and tied to the same IP addresses?
because that simply does not work (reliably). It would depend on AS-paths of the same length from every possible source. Simple, reliable and quite stylish is another way: Choose primary and secondary location by announcing more specifics at Sacramento, e.g. all networks as /20 subnets. As "longest match always wins", any source seeing both routes for an IP address will choose Sacramento. The only way traffic could reach LA would be a missing route to Sacramento. In any other case, Sacramento is chosen. Thus, if Sacramento (manually or automatically) stops announcing the /20s, LA's /18 and /19 will be chosen. CAVE: This is no failover solution for single services, just for whole subnets depending on the announcement at Sacramento. CAVE2: My suggestion creates inconsistent announcements for the source AS. That may or may not be a problem. Kind regards, Malte -- Malte v. dem Hagen Abteilung Technik - Network Operations Centre ----------------------------------------------------------------- Host Europe GmbH - http://www.hosteurope.de/ Welserstrasse 14 - D-51149 Köln - Germany Telefon 0800-4 67 83 87 - Telefax 01805-66 32 33 HRB 28495 Amtsgericht Koeln - UST ID DE187370678 GF: Uwe Braun - Alex Collins - Mark Joseph - Patrick Pulvermüller -----------------------------------------------------------------
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Current thread:
- Failover solution using BGP Naveen Nathan (Dec 30)
- Re: Failover solution using BGP Chris Ely (Dec 30)
- Re: Failover solution using BGP Doug Schaapveld (Dec 31)
- Re: Failover solution using BGP Chandler Bassett (Dec 30)
- RE: Failover solution using BGP Braun, Mike (Dec 30)
- Re: Failover solution using BGP Malte von dem Hagen (Dec 30)
- RE: Failover solution using BGP Braun, Mike (Dec 30)
- RE: Failover solution using BGP Austin Wilson (Dec 30)
- Re: Failover solution using BGP William Herrin (Dec 30)
- Re: Failover solution using BGP Naveen Nathan (Dec 30)
- Re: Failover solution using BGP Florian Weimer (Dec 31)
- Re: Failover solution using BGP Roland Dobbins (Dec 31)
- Re: Failover solution using BGP Florian Weimer (Dec 31)
- Re: Failover solution using BGP Roland Dobbins (Dec 31)
- Re: Failover solution using BGP Chris Ely (Dec 30)
- RE: Failover solution using BGP Bryant Valencia (Dec 31)