carrier sensing: easy in some technologies (wire), hard in others

CSMA/CD used in Ethernet

switches have link-layer addresses associated with their interfaces

used for layer 3 (network layer) forwarding

(for most LANs) burned in NIC ROM, also sometimes software settable

MAC flat address: portability can move interface from one LAN to another.

is used to translate between network-layer addresses (IP addresses) ,. and link-layer addresses (MAC addresses). I

like Social Security Number

… allocation administered by IEEE

ARP table: each IP node (host, router) on LAN has table

TTL is

recall IP address …

time after which address mapping will be forgotten

The query ARP message is sent within a broadcast frame, whereas the response ARP message is sent within a standard frame.

TTL is typically … minutes

Ethernet dominant …

popular through mid 90s

each "spoke❞ runs a (separate) Ethernet protocol (nodes do not collide with each other)

used to synchronize receiver, sender clock rates

if error detected the frame is dropped