Router between ASA and ISP

[RTOI925]

My ISP serves me 2 blocks of IP's , both /29 networks.  One block is for our production environment and one block is for a separate project. The wire from our ISP comes from the demarcation point and goes directly in a hub. One wire on the hub is going to my ASA 5545 (production network), another wire is going to a switch that is serving computers for the separate project. I need to remove this hub and put a router in it's place, but I don't know how to set up the routing. I have a Cisco 1921 router with a 4 port switch module, and a 2 port GE module. I know I can use of the GE ports and attach it to the outside interface on my ASA, and then use another and attach it to my switch feeding the separate network.  But I am lost on how to configure the interface that will attach to my ISP's router. The only information they can give me are the 2 subnets they are providing us. If I give the interface an IP address on subnet 1, then subnet 2 won't be able to go through it and visa versa.  Do I create 2 sub interfaces, one for each network and then set up static routing?  Any help would be appreciated!

[pieterh]

you first need the check te "hub". is this a provider device?

than don't replace it without consulting the provider.

by the description "one cable in, two cables out" it most likely is not a "hub"  in the sense of old-times ethernet-hubs.

my guess is you need to call this a CPE, which is actually some kind of switch that has a trunking port with multiple vlans in and two access ports with each a single vlan out.

[rasmus.elmholt · Accepted solution]

Do you really have a HUB in your network? And I think the simplest solution would be to install a switch instead of the HUB.
Otherwise you need to get a new /30 subnet between the ISP and your new router. And then move the two /29 subnets to the LAN side of the router towards your ASA's.

[RTOI925]

Sorry for the confusion, it's not a hub it's actually a TAP, but essentially acts as a hub.  We own the tap, and we want to replace it with the router.

[RTOI925]

This is what I thought we might need, a /30 block as a point to point connection, thank you for the reply!