hw4 out, internet checksum algorithm and psuedocode, in book on pages 94,95

IP
	connectionless, unreliable network layer protocol
	best effort services, no guarantee of error free packets, no guarantee of order of delivery, no guarantee of delivery
	relies on upper layer transport control protocols for reliability

fields related to fragmentation
	identification: 16 bits, same ID for all fragments of a packet
	flags: 3 bits, no info for 1st bit, 2nd bit is for DO NOT FRAGMENT, 3rd bit is for MORE FRAGMENTS ON THE WAY
	fragmentation offset: 13 bits, relative position of the fragment to the whole packet measured in units of 8 octets
example
	a packet size of 4K octets is to be fragged into 3 frags
	octets in orig packet are 0-3999
	hosts/routers that fragment packets choose the size such that the first octet number is divisible by 8
	1st 2 frags are 1400 octets with M==1 and 3rd is 1200 octets with M==0
	offsets: 1: 0, 2: 175, 3: 350
	
IP packet embedded inside frame
(address resolution protocol)arp gives you MAC from IP
ARP is a local protocol

DNS (domain name services) name to IP resolution
local name servers
root name servers: 13 (i'm sure this is lies)
authoritative name server: where host registered its name/ip address

recursive DNS: request traverses up tree to a point of commonality (sometimes the root server), and then down the tree to the authoritative name server
iterative DNS: request gets a "I don't know, but try here" and bumps over to that server to continue resolution


routing algorithms
	two processes required to accomplish IP packet delivery:
		routing (disco and selection of path to dest, layer 3 func)
		forwarding (inserting ip packet into layer2 frame and forwarding frame to next hop, layer2/3 func)
	routing tables built up by routing algorithms with components:
		dest net address: net portion of IP for dest netowrk
		subnet mask: used to distinguish the net address from the host address
		ip address of next hop: where the packet is forwarded for delivery
		interface: which interface the packet actually goes out