redundancy with static route and OSPF

[sean.phan]

Here is my network configuration:

10.10.10.0/24 -(Firewall)--- R1 -- (static)ISP ---- R2 --- (OSPF)---R3----(OSPF)--- HQ -----

- R1 connects to R2 through ISP with a default route to R2

- at R2

+ Subnet 10.10.10.0/24 is redistributed into OSPF

+ Static route Ip route 10.10.10.0/24 <ISP>

- at R3

Subnet 10.10.10.0/24 is seen at R3 through OSPF

now i have a new dedicated ethernet link between R1 and R3

What i want to achieve is the redundancy for the 10.10.10.0/24

- Traffic to HQ shall go to ISP if R2 is reachable through ISP

- If the link to R2 fails traffic shall go to R3

With the following condition:

1. I am not allowed to configure dynamic routing between R1 and R2

HSRP won't work because

If the ISP link fails traffic will be sent to R3 but because the OSPF static route redistribution

at R2, the traffic going back to 10.10.10.0/24 through R3 will be dropped by ISP

What is the best solution to my problem ? Appreciate your help

[Edison Ortiz]

You can use the 'protocol ipIcmpEcho' option within the rtr command.

However, I still don't have a solid understanding on how R2 determines the remote network is down.

You answered my query with:

"When connection is lost the link between R2 and ISP will still be UP most of the time"

Can you elaborate ?

Thanks

[sean.phan]

Sorr for the confusion, The R2 to ISP link is Ethernet so the link is always up even the remote subnet is unreachable unless we manually unplug the cable

[Edison Ortiz]

Sean,

My suggestion is configuring BGP fully meshed between R1, R2 and R3.

This will take care of your problem without the need for static routes and Cisco's SAA.

It will be a much cleaner config and it will allow you full redundancy among peers.