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).
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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