I want host to switch to another router as their gateway without I manually change their gateway address. How can I configure all of my internal/local routers to support this requirement?
On each router, go to their inside-interface's configuration mode, do and type these:
1. Add virtual IP address.
Usually virtual IP address is the first usable IP address from the IP address segment. So like this:
R1(config)#int f0/0
R1(config-if)# standby ip 192.168.1.1
2. Set which router be the preempt
3. Set the priority
Virtual mac-address is will be used as L2 address of L3 virtual interfaces.
Where did this virtual mac-address came from?
At first, I think both routers will do some kind of negotiation upon their will be used virtual mac-address. But it is not. The virtual mac-address is decided/derived by each router directly, via configuring group number, group number 1 in this case, into their standby command. They don't need to negotiate the mac-address using sending and receiving packet.
So if you configure R1's with: standby 1 ip address 192.168.1.1, then it will directly derives its virtual mac-address as: and if you configure R2's with: standby 2 ip address 192.168.1.1, then it will directly derives its virtual mac-address as: .
Both router will start sending an ARP gratuitos packet (L2 packet that have source-address himself and destination-address himself also) and switch that connect to them will start record it inside its mac-address table. Like this:
On each router, go to their inside-interface's configuration mode, do and type these:
1. Add virtual IP address.
Usually virtual IP address is the first usable IP address from the IP address segment. So like this:
R1(config)#int f0/0
R1(config-if)# standby ip 192.168.1.1
2. Set which router be the preempt
3. Set the priority
Virtual mac-address
What is virtual mac-address?Virtual mac-address is will be used as L2 address of L3 virtual interfaces.
Where did this virtual mac-address came from?
At first, I think both routers will do some kind of negotiation upon their will be used virtual mac-address. But it is not. The virtual mac-address is decided/derived by each router directly, via configuring group number, group number 1 in this case, into their standby command. They don't need to negotiate the mac-address using sending and receiving packet.
So if you configure R1's with: standby 1 ip address 192.168.1.1, then it will directly derives its virtual mac-address as: and if you configure R2's with: standby 2 ip address 192.168.1.1, then it will directly derives its virtual mac-address as: .
Both router will start sending an ARP gratuitos packet (L2 packet that have source-address himself and destination-address himself also) and switch that connect to them will start record it inside its mac-address table. Like this:
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