HSRP with two T1s different networks

[mmonti]

Hi,
I have two T1 lines from the same isp with different POPs. The T1s have two /27 blocks assigned to them.

How can I use HSRP if the physical interfaces of the two routers are on diffent networks? I know with HSRP you assign a shared, virtual IP to the the two physical interfaces but the two interfaces are on diffent networks.

-Monti

 

[lui3]

Monti,

HSRP was designed to provide gateway redundancy in a common LAN environment since their was no easy method of doing this previously outside of assigning 2 gateway addresses or using ICMP IRDP or some other mumbo jumbo.

The real question here is what are you trying to accomplish?

With two T1s you already have internet pop redundancy. With a routing protocol like EIGRP you could enable load balancing over equal or unequal cost routes and achieve failover or you could use static routes with different ADs to achieve similar results without load balancing. Better yet if you could setup BGP with redistribution into you LAN you could have perfect failover for the gateway.

HSRP would come in handy when you had two routers on the network both providing gateway access and you wanted them to share the same IP address for client configurations purposes. This works on seperate vlans as well. Really all depends on the purpose of your design.


Mike
Net Engineer
CCNP/CCDA

 

[mmonti]

Mike,
I am looking for gateway redundancy.

The two T1 lines feed into two Cisco 2620 routers. The reason I asked is that in all of the Cisco literature and books I read when using HSRP the physical, ethernet interfaces were always on the same subnet.

Also, when I use the public addresses to assign to my companies websites, do I need to assign an address from each T1? The two T1 routers' WAN interfaces are unnumbered IPs and my ISP said I only need to assign the websites an IP from one T1. If that t1 goes down somehow it is rerouted to the other T1(through HSRP????).
They kind of lost me on that one.



-Monti

 

[NetEng631]

HSRP will not help you in this situation.