Our proposed setup is the following. We are using the same ISP.
Corp RTR---->ISP (20MB)
| 100MB Metro LAN
DR RTR---->ISP (20MB)
We have been assigned a /24 block from our ISP and I would like to know the best design to load balance and failover to the Metro LAN in the event of a failure.
Am I correct in following the documentation from the link below?
Thanks in advance.
I guess you have split the public /24 address block in two or more parts internally in your domain and that edge routers are advertising the /24 as a result of using an aggregate address or a static route to null0 for the /24 IP network.
if the ISP is only one you could try to setup an agreement in order to send also specific /25 routes with them.
the other /25 could be advertised with your own AS prepending
so it could be:
COrp: sends out first /25, aggregate /24 second /25 with As path prepending
Hosting: sends out second /25, aggregate /24, first /25 with AS path prepending
ip prefix-list firstblock seq 5 permit x.y.z.0/25
route-map CorpToISP permit 10
match ip address prefix firstblock
set as-path prepend yourAS yourAS
route-map CorpToISP permit 20
! second empty block to advertise the other prefixes
router bgp yourAS
neigh ISP-ipaddress route-map CorpToISP out
Hope to help