My question is simple. How do you handle default gateway assignment in DHCP to guest vlan when multiple switches are in place. Lets say Microsoft DHCP server configured, ip helper-address configured in switches, SW1 has a guest vlan interface IP of 172.16.20.1 and SW2 has 172.16.20.2. How can we make DHCP assign 20.2 as default gateway to any dot1x disabled PCs in SW2 and 20.1 to ones in SW1?
I think what you are asking is how you assign default gateway to PC/host depending on which switch/router they are connected to? The answer is it does not matter which switch they are connected to, as long as the default gateway is reachable from either switch. Just pick one, or better yet, do HSRP, that way you would not have both routers/switches backing each other up. Or if this is not what you are asking then maybe it's better to have to separate guest vlan one for each switch.
Does that make sense?