MAC addresses and ARP32-bit IP address:network-layer address for interfaceused for layer 3 (network layer) forwardingMAC (or LAN or physical or Ethernet) address:function:used ‘locally”to get frame from one interface to another physically-connected interface (same network, in IP-addressing sense)48 bit MAC address (for most LANs) burned in NIC ROM, also sometimes software settablee.g.: 1A-2F-BB-76-09-AD