overlaps with GigabitEthernet - 1 Router 2 Core-Switch

[d.business]

Hey,

I have one router an 2 core-switch. I want to config FHRP for the 2 physical interfaces. But when i try to config the second sub interface i get the error: 10.1.10.0 overlaps with GigabitEthernet0/0/0.10 because its the same ip obviously.

how do i have to config the router physical and sub interface so if the 1 core-switch is offline the other one is doing his job?

Should become an redundant network.

And i have multiple switches behind the cores with multiple Vlans routed by the Router.

 

[Reza Sharifi]

Hi,

You only have one router, and so, FHRP is not going to help. FHRP would be useful if you had 2 routers and you want to provide redundancy between them. Also, you can not assign the same IP to a physical interface as well as a sub-interface. For that to work, you would need to delete the IP on the physical interface and create 2 sub-interfaces and use 2 different subnets (one per sub-interface).

HTH

[d.business]

Thank you for the answer

Good to know. But can you tell me how i can use 2 core-switch on 1 router? 

If the left one is dead the right on need to be the backup.

The problem is, that if the left on is offline the default gateway is missing because the other core is on a different port from the router. Because of this i thought about FHRP with an virtual ip for the 2 physical interfaces with the 7 sub interfaces on them for the different vlans.

[Reza Sharifi · Accepted solution]

What type of router is that and what version of IOS are you using?

You may have to explore BVI. See link for examples:

https://www.cisco.com/c/en/us/support/docs/lan-switching/integrated-routing-bridging-irb/200650-Understanding-Bridge-Virtual-Interface.html

HTH

[d.business]

This is exactly what I needed. Thank you