Multihoming - Design Question

[Aholmes]

We have two subnets on our LAN to segment traffic and we are using a windows box as the LAN subnet router. I would like to offload the routing to a Cisco 3640 that is our WAN router with two Ethernet ports. I’m only using one Ethernet port at this time with an ip address on subnet A , Can I multihome the active Ethernet card to use both an IP address on both Subnet A and Subnet B to route traffic between the two or should I setup the second Ethernet card for subnet b and route between the two...

or, is there a better way to replace my windows box.

I sure appreciate the help.. thanks so much.

Andrew

 

[baddos]

Yes. You need to look into configuring sub interfaces. Depending on what layer2 you have (managed switches or unmanaged) you can setup dot1q subinterface or use ip address secondary.

 

[Aholmes]

Thanks so much. Do you know if you have to use vlan on the sub interface or can I just use secondary IP?

 

[baddos]

Are your switches setup with vlans currently? If so it would be best to use a subinterface with vlan tags on your router. If not, then secondary interfaces will work but it's not the best way.

 

[burtsbees]

Subnet A on one ethernet port, and subnet B on the second ethernet. No need for vlans or subinterfaces. The traffic will already go between the sunbets with no additional configuration since they are directly connected.

Burt