HSRP with 2 routers and 4 ISPs (and possibly VPN)

remi-reszka · ‎05-12-2010

Hi there,

Here it comes a difficult one. We have 4 dedicated links at each site, each link with different ISP. All ISP routers are under their management so we don't have access. What we were thinking to install 2 additional routers configured with HSRP and each one connected to 2 ISPs, how would that work? The active router would track routes through each ISP connected to it and should both ISPs be down the standaby router would take over with another 2 ISPs? Would each HSRP router be able to load sharing between 2 ISPs connected to it?

To be honest it seems a little bit complicated. Are there any other solutions then that? How about one big router with 4 WAN adn 1 LAN links? I guess with one router apart from WAN redundancy we could also do load-sharing correct? But here we have single point of failure...

Now most difficult part, what VPN technology we could go for to configure VPN resiliency on all 4 ISP links? Would DMVPN or GETVPN work here?

Thanks a lot for any thoughts on that.

andrew.prince · ‎05-12-2010

You are not 100% clear you state

"We have 4 dedicated links at each site, each link with different ISP" This indicates 4 seperate sites?

"What we were thinking to install 2 additional routers configured with HSRP and each one connected to 2 ISPs, how would that work?" Why 2 routers, if all you want is ISP redundancy - install 1 router?

"Would each HSRP router be able to load sharing between 2 ISPs connected to it?" HSRP is a dynamic failover protocol - not load balancing. GLBP is better suited

" How about one big router with 4 WAN adn 1 LAN links? I guess with one router apart from WAN redundancy we could also do load-sharing correct? But here we have single point of failure" Install 4 seperate routers - however that breeds it's own problems!

"Now most difficult part, what VPN technology we could go for to configure VPN resiliency on all 4 ISP links? Would DMVPN or GETVPN work here" Is DMVPN for remote site VPN connectivity? GETVPN - is this for Client Remote access?

remi-reszka · ‎05-12-2010

Hi Andrew and thanks for response.

We have several sites and 4 ISPs at each site. I know it sounds crazy but the owner wants to accomplish 99.999. One router is an option but again a risk of single point of failure arises. 4 routers to much expense and more complicated setup, 2 routers still an option. VPN will be site-to-site only, I mean sites to HQ, in the future could be inter-site like DMVPN.

Say we go for one router with 4 WAN connections and 1 LAN, what VPN technology could we employ here with use of all 4 ISPs at each site to provide VPN redundancy?

andrew.prince · ‎05-13-2010

The biggest issue with whatever you decied is going to be IP addressing. Failover, L2L & RVPN's etc all depend on src/dst

What is the current IP scheme with the providers? Do you have a ASN? A dedicated IP range say class C ??