[lug] MAC addresses, multiple IP on a single NIC, DHCP

D. Stimits stimits at idcomm.com
Thu Aug 1 11:08:01 MDT 2002

I'm curious about something. If I have a single NIC on a machine, and it 
is set up for multiple IP addresses (one Internet routeable, the other 
non-Internet routeable for talking only to local machines), then it 
seems that hardware somewhere will get confused. If I use this basic 

  CABLE_MODEM (DHCP issues to each machine)
       |<- (invisible bridge/firewall here)

...and if each machine has 1 NIC with 2 IP addresses, such that the 
non-Internet routeable is used to talk between machines (and thus avoid 
going through the cable modem), but each machine is DHCP assigned via 
the cable modem service, is it possible for the system to function 
correctly? I ask this mainly because the switch must be talking to 
machines via MAC address, and I wonder what happens when a NIC responds 
with two IP addresses...can the switch associate two IP's with one MAC 
address (this is a reasonably nice Linksys 8-port switch)?

D. Stimits, stimits AT idcomm.com

PS/OT: Does anyone here know if Win2k and Win98 are capable of multiple 
IP's on a NIC, where one is static/non-Internet-routable, and the other 
is DHCP?

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