Addresses, Subnets, ARP, DHCP, ICMP
Tying up IP pieces. Including IP Addresses, subnet masks and the like. This is all at a rather broad upper level, but hopefully it starts to inform you about some of these ideas and protocols.
Addressing: 0:20 – brief IPv4 overview
Subnetting: 1:39 – all those bits are useful for routing
ARP: 5:48 – tie together IP and MAC
DHCP: 8:39 – get all your IP configuration automagically
ICMP: 10:49 – how does IP report errors? how’s traceroute work?
Follow up notes:
ARP: I might not have sold completely WHY ARP is needed. If R1 receives a message “for” H1, to transmit that at the link layer appropriately, it needs the MAC address of H1 to do so appropriately. ARP helps with this by letting R1 know this as H1 comes online. Think of this like a USPS piece of mail that you receive at a home. You then have to figure out which individual that belongs to. It may not be appropriate to broadcast the contents of that message to EVERYONE in the house and it may be wasteful to do so for some subnets.
DHCP: Misspeak here: Each Ethernet port was attached to an IP address. If not served by a DHCP server, you had to type in all the config yourself. But, almost any modern network will have a DHCP server even if each address is attached to some port.
mac address
