I have a couple HSRP related questions.
We have recently moved into a data centre providing us with 2 ethernet links to the internet. They are running HSRP on both of their switches, and both switches are in "active" state and are isolated from each other.
We purchased 2 x 2821 routers for our devices. We are planning to run HSRP between our routers as well.
The problem is the data centre's switches do not communicate with each other (aka not connected to each other) and therefore our router's HSRP does not work because our routers are also not connected to each other on the WAN side. If I place a L2 switch between our routers and the Data Centre switches, not only does the ISP's HSRP start to work, but our does as well, this is expected.
I spoke with the data center and they said that their switches are running HSRP in active active? Where both switches are active.
My question is, is this normal for a data centre to assume we are bringing an L2 switch in (they suggested I do this when I asked them about this)? Given all the redundancy configured and required, this L2 switch would be a single point of failure. Are there any configurations in which I could make this scenario work without an L2 switch? Or should I demand that the data centre connect their switches? See attached diagram.
I am also running HSRP on the LAN side of things on the same routers. What happens in the scenario when RouterB is the LAN's active HSRP router, but RouterB's WAN is down (not link). Should I use HSRP with SLA's to track pings out the WAN interface of the routers, would that then make the router with the "down" WAN link to go into standby for the LAN? Is this is the best solution for this scenario?