[jggimi]

Originally Posted by beiroot

Any other ideas?

Topology thoughts.

I began using all three NICs on the alix2d13 systems in a topology similar to this common single router configuration:

1. ISP network
2. LAN network
3. DMZ network

I didn't have a DMZ network requirement -- as the ALIX systems are deployed in pairs with carp(4) for redundancy, I used the third NIC for router-to-router private networking. The third NICs were interconnected with a cross-over cable.

1. ISP network
2. LAN network
3. Private router-to-router network

But over time, my topology requirements grew. Today, a pair of ALIX systems now routes to 8 LANs. Yet I've reduced the number of NICs I use on each ALIX machine to two, leaving the third NIC empty. I trunk(4) the two NICs I am using, and then deploy vlan(4) pseudo-NICs as needed.

Adding 802.1Q VLAN capability to my Ethernet networks has been the most significant change I've made to them since deploying twisted-pair Ethernet. Hubs -> unmanaged switches was just performance improvement. 10 -> 100 -> 1000baseT was just bandwidth improvement. Neither altered the network topology.

The only reason I'm not using all three NICS is that I'm out of ports on my managed switch. If there were spare ports, I would add these NICs to the trunk().

With a managed switch, even a single-NIC computer could be deployed as a router -- this is a so-called "router on a stick." Depending on your bandwidth and connectivity requirements, a managed switch gives you much more flexibility in systems choices. You need not necessarily restrict yourself to considering 3-NIC or 4-NIC systems.