What is the ixp1 interface, and can it be used for anything useful?
The IXP420 has two network interfaces built in, ixp0 and ixp1. ixp0 is wired to the ethernet socket on the back through the RealTek PHY chip. ixp1 however is not connected to anything at all, this means that the IXP420 ixp1 (MII2?) balls/routes have to be traced and connected to an ethernet controller before being able to use ixp1.