thanks.
No, because both routers are reached through the same L1/L2 medium, so Quagga can't use link-state to determine reachability of the next-hop. You could fix that by getting rid of the switches, and just having a bunch of router interfaces facing two Ethernet interfaces on each server, which would remove some points of failure, and would be a good idea if you can spare the router interfaces...
Do you mean Quagga's OSPF route has higher priority than static route? or even there is static default route configured, once Quagga detects link to default router is down it will replace 0.0.0.0/0.0.0.0 in host routing table?
> 2) If each server is configured two default router ( > router-1 & > router-2), or each server learn route 0.0.0.0/0.0.0.0 > by OSPF ( our border router inject default route into > OSPF ); there should be > two equal cost path to 0.0.0.0/0.0.0.0 on each DNS > server, the DNS server should disperse any outgoing > packets onto the two paths, will > that do harm to DNS service ?
Nope, no problem, particularly so long as the two routers are iBGP peers, so they'll both (for the most part) have the same idea of what selected paths are.
I don't understand why should both routers be iBGP peers. In fact, iBGP does not run on that two routers; the two routers are only members of OSPF backbone area who only run OSPF; only border router ( at the edge of our network) runs BGP and enject default route into OSPF backbone area. Although all DNS servers are cache server, we have to open 53/TCP to allow resolver using TCP protocol. For example, server-(1,3)--switch--router-1--\ | (OSPF only) router3--host server-(2,4)--switch--router-2--/ if that possible that router3 or router-1 dispers packets of the same TCP connection to different path? Is there possibility that a DNS requests are divided into multiple UDP packets?
> 3) Is there any requirement on BIND to fit to such > multipath routing situation?
Nope. BIND doesn't know what's going on that far below it.
Do I only need to configure BIND to origin request from administration IP address ( configured on NIC and different from DNS service address)? regards Joe __________________________________________________ Do You Yahoo!? Log on to Messenger with your mobile phone! http://sg.messenger.yahoo.com