The Public Network (Ethernet Rails) - HP NetServer AA 4000 Reference Manual

Ch 4: Networking Explaineds

The Public Network (Ethernet Rails)

A pair of network cards, one in each IOP, in the same PCI slot
numbers constitutes a "public rail." There are several different
terminologies used for essentially the same network type. For the
network cards that the IOPs use to intercept client traffic on the
network, these cards may be referred to as the public network, a
public rail, or an Ethernet rail.
As far as the requirements for the AA 4000 software go in regards to
the network cards to be used as the public network, any NDIS 4
compliant network card with Windows NT 4.0 drivers will work.
These cards also must support the capability of having their MAC
addresses "soft-set" by the Marathon software into the NT registry.
This is part of NDIS 4 standards, so any of these network cards
should comply. For the purposes of the HPAA system, the public
network cards will also be HP 10/100 TX cards.
Additional public rails can be added to the array. Up to four public
rails, or four pairs of NICs, can be added to the IOPs in addition to
the IOP link. For a NetServer LH 3, the five network cards would be
inserted into PCI slots 2 – 6 with slot 6 functioning as the private
link.
Each public rail as represented by the pair of NICs is constantly
"listening" on the network wire for its destination server MAC. For
the purposes of client access, there is only one NetBIOS server name
for the array, as defined in the CE, and only one IP address per
public rail (multiple IP addresses can be assigned to a the virtual
network adapter the same as any other NIC in a standard copy of
Windows NT). Both NICs in the rail are listening and prepared to
pass traffic to the CEs, but only the NIC that is currently online will
actually pass the traffic. The other NIC will begin to pass the traffic
Network Server Division 4-7