hub
repeats all messages to every port. one collison domain. physical layer
collison domain
how many devices can send of receive at once
broadcast domain
how far a broadcast will go until it stops
problem with CSMA/CD
the more devices you have, more devices listening and trying to send. limit to around 30 devices. switches solve this issue
jam signal
collison detected. everybody stop, i need to resend my signal
bridge device
two side device. learns peoples mac addresses on both sides of the network. only send messages across if needed. split your network into two collison domains. not as popular anymore
switch device
broadcast MAC address
all F’s