----- Original Message -----
From: "Andrew Fort" <afort@choqolat.org>
To: "pankaj" <pankaj@worldgatein.net>
Cc: <cisco-nsp@puck.nether.net>
Sent: Tuesday, November 20, 2001 12:49 PM
Subject: Re: [nsp] BGP Multihoming -how to announce backup route???
> On Tue, Nov 20, 2001 at 12:13:20PM +0530, pankaj wrote:
>
> > One more thing is that suppose if i will not enable BGP for my main
> > provider(ISPA-keeping static announcement as it is.) and i will only
> > configure BGP with my backup provider( ISPB)
> > and announceing my networks with AS prepends. Will it work????
>
> this depends on how your upstream announces your routes (whether they will
prepend, >etc). if the address space in question is all "yours" (i.e,.
assigned to your AS by an RIR like >APNIC, ARIN or RIPE), then generally
speaking it will still work. you should liase closely >with your upstream
who is statically routing your space to get the best result. also, note
that >your routes will be being originated into the global routing tables
with two different >terminating ASes, which is best avoided (i.e., run BGP
to both providers if at all possible).
PP> Address space in mine from APNIC
Now suppose if i think like this, if i come to know that isp A goes down
than i need to announce my network with higher priority to ispB than ispA ,
how should i do this announcement. Any idea??
thanks
pp
>
> If you're talking about provider assigned space, the short answer is no,
due to ISP-A (the provider assinging you the space) aggregating their
customer address space announcement.
>
> In this case, you may like to investigate if enterprise multihoming, as
described in RFC2260, could benefit you. A cisco whitepaper on this is
here:
> http://www.cisco.com/warp/public/cc/pd/iosw/ioft/ionetn/tech/emios_wp.htm
>
> -amf
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