I'm not sure exactly what you're saying so let me rephrase it and you
let me know if I have it wrong. It appears that you have two separate
routers connected to two separate ISPs and you're running iBGP between
the two. You want the traffic destined for ISP1 to go out one link, but
do you want all the rest of the internet traffic to go out the second
link? Or do you want your routers to choose the best exit point no
matter what the destination?
This can be simple or it can get very complicated. Let's assume you
have a single ASN and a block of IP addresses large enough to stand
chance of not being aggregated or filtered. If either of your ISPs
chooses to filter your addresses or if they don't advertise your
specific prefix separate from their aggregate, then you're going to run
into problems. We'll assume you have at least a /24 assigned to you.
If you want to allow only traffic destined for ISP1 to go out that link
and have the rest go out the other link do this:
1. Advertise your network to both ISPs.
2. Accept customer-routes only from ISP1
3. Accept whatever you feel like from ISP2, a default route would work
just fine.
If you don't accept a default from ISP2, then create a static default
route that will handle traffic for unknown destinations.
If you want to do a little bit better job of load balancing (you'll
never really achieve perfect load balancing) then you could accept full
routes from both ISPs if your routers can handle it.
Another option is to accept customer-routes only from both providers
and then have two default routes to handle unknown prefixes.
I'll let someone with more experience than I handle the scenario if you
have two ASNs.
HTH,
John
>>> "Dean" <[EMAIL PROTECTED]> 3/16/01 8:40:00 AM >>>
Dear group,
I come across a real bgp question in my work,that is:
I want to load balance and backup between my 2 ISPs,they also have
their own
AS numbers and have a direct connection between them as well,I use 2
edge
router running iBGP with eachother and eBGP with my 2 ISPs.The question
is :
.if I want to make the traffic for ISP1's AS pass through one
connection and
the other traffic for Internet through ISP2,how to config my edge
router in
my one AS?
.if I have 2 ASs,what about the story?
Avobe 2 conditions,does it need some config in my ISPs BGP neighboors?
I am appreciated if you can give me some idea.
TIA
Dean
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