27.3 MAC Addresses

   

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A MAC address is a unique address assigned to each network interface adapter. It is a 48-bit address and is represented as a 12-digit hexadecimal number. This is also called a physical address, station address, Ethernet address, or hardware address. Data frames that are sent on the physical layer contain source and destination MAC addresses. Usually every host on a LAN listens to all incoming data. If a received data frame contains a destination address that matches the MAC address of the host, the frame is transferred to the network layer; otherwise , it is dropped.

Every network interface adapter installed in a system has its own unique MAC address. Thus, a host has as many MAC addresses as the number of network adapters installed. HP-UX provides commands to check the MAC addresses of installed network adapters. The most common command is the lanscan command. Output of this command is like the following.

 #  lanscan  Hardware Station        Crd Hdw   Net-Interface  NM  MAC       HP-DLPI DLPI Path     Address        In# State NamePPA        ID  Type      Support Mjr# 10/4/16  0x080009D41DBB 1   UP    lan1 snap1     1   ETHER     Yes     119 10/4/8   0x080009D481F6 0   UP    lan0 snap0     2   ETHER     Yes     119 10/12/6  0x080009F02610 2   UP    lan2 snap2     3   ETHER     Yes     119 # 

The second field of the output under the Station Address column heading is the MAC address of installed network adapters. It starts with 0x showing that it is a hexadecimal number.

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