This is the logical view of what you're trying to achieve:
Configure the router priorities for both VRRP 'a' and VRRP 'b' as follows:
- Router 1: 110 (master)
- Router 2: 100 (backup)
The configure interface tracking as follows:
- Router 1 VRRP a: track interface R1b with a track priority of 90
- Router 1 VRRP b: track interface R1a with a track priority of 90
- Router 2 VRRP a: track interface R2b with a track priority of 90
- Router 2 VRRP b: track interface R2a with a track priority of 90
If interface R1b goes down, Router 1 will change its VRRP 'a' priority to 90. This priority is now less than the VRRP 'a' priority that Router 2 has, so it will preempt and take over mastership for VRRP 'a'.
In addition, because interface R1b has gone down, then the VRRP hello packets will fail across VLAN 'b'. This will be detected by Router 2 (after failing to receive a hello packet within the dead timer interval), at which point it will take over mastership for VRRP 'b'.
If interface R1a goes down, then in a similar fashion, Router 2 will take over mastership for both VRRP groups (Router 1 VRRP 'b' priority = 90, and the VRRP hello packets will fail across VLAN 'a').
If either interface R2a or R2b goes down, then Router 1 will continue to be master for both VRRP groups.
Note that the priority value I've chosen above are quite arbitrary -- you may want to choose different values. Also, if the VIP address of a particular VRRP group is the same as the interface address for one of the routers in that VRRP group, then that router will automatically take a priority of 255 (i.e. it will always be the master unless that interface goes down).
As a side note, to get the above logical architecture, you will need a physical architecture similar to the following:
You can read up on VRRP on Wikipedia here:
http://en.wikipedia.org/wiki/Virtual_Router_Redundancy_Protocol
Brocade's VRRP documentation is here:
http://www.brocade.com/support/Product_Manuals/ServerIron_SwitchRouterGuide/VRRP.7.2.html
Brocade also have some VRRP configuration examples here:
http://www.brocade.com/support/Product_Manuals/ServerIron_SwitchRouterGuide/VRRP.7.11.html
Hope this helps! :)
Since your switch is stackable, you could configure link aggregation between your devices and your switches, being one interface on one switch and another interface on the other switch.
Should any of the switches fail, all traffic would still be able to reach destination with a few packet drops but quick convergence without the need to reconfigure. As a bonus, you'd get double bandwidth.
This switch (as a stack) can be configured with up to 128 LAGGs.
Best Answer
No. You are going to have a SPoF no matter what you do with a single ISP link. A switch, hub, your ATS idea, etc. all represent a SPoF, as is the single link and single ISP device to which the link connects.
Even with the big, pricey, multi-supervisor switch, you will be at the mercy of a line card, or even a port on the line card. In fact, we have found that your standard business-grade equipment is much more reliable than the data circuit to which we connect the equipment. If you want to eliminate the SPoF, you need dual circuits from different ISPs in different physical paths to the site.