BGP and 2 ISP. Default gateway problem :(

[ieasm0001]

Hi, i have big trouble, maybe sombody knows how i can solve it.

Look, i have network like in attachement. I have full view and default gateway from ISP 1 by BGP, then for R1 and R2 def. gw is ISP1 IP. For R3 and R4 is similar situation but from ISP 2. In case if link 1 goes down then default gateway must be from ISP 2. But my problem in following:

when link 1 goes down, i still receieve default gateway from ISP 1 becouse BGP  session doesn't go down. I tried to solve the problem in that way: i created ip sla track and attache it to static route(0.0.0.0/0). My ip sla test ping R0 IP address and if it goes down then  traffic will go through  ISP 2, but i think that it is not the right way, becouse R2 still recieve default gateway from ISP1. How i can solve it without ip sla?

[andrew.prince]

change your bgp timers from the default say hello 3 dead 6 to isp1 and isp2, the lowest negotiated timers win.

HTH

[ieasm0001]

I think u don't understand me. Link beween R1 and ISP 1 is available and BGP session is OK, but internet doesn't work, becouse ISP 1 has some poblems with there network and i want to forward trafiic through ISP 2 if i can't reach R0 IP through ISP1

[andrew.prince]

Well not to sound rude - but welcome to the internet.  Everybody who runs routers with BGP and peers with providers faces the same issue.  As your router is receving a valid route from the ISP, why would'nt it use it ?? - that's the whole point.

There is no right or wrong solution to this - if IP SLA works for you, crack on.  On the other hand if it happended to me I would be picking up the phone and giving my ISP a peice of my mind, along with a request to get some of my circuit rental money back. But loops and blackhole routing occur in the internet - it's just one of those things I am afraid.

JMTPW.

[andrew.prince]

another option is to get your isp to send you the whole Internet routing table instead of just a default route.

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