Chap 4
* TCP functions:

	flow control, error control, par, port number, 
	sequence number, window size, ack number

* TCP applications: 20, 21, 23, 25, 80, 110, 179, 443, 

* UDP applications: DHCP, DNS, BootP, TFTP, SNMP, RIP, 
	real-time applications (movie, news, video streams, 
	audio streams, voice or IP, 

* port numbers: <1024, 1024~49151, 49152~65535

* window size



BGP uses TCP 179



chap 5

* ip - connectionless, best effort, media independent

* broadcast domain, collision domain

* commands to get routing table:

	show ip route (cisco),  netstat -rn,  route print,  
	ip route (ubuntu)

* routing table:
	
	destination address, next hop, metric, default gateway (?)

* default gateway

* destination address not found --> packet dropped

* key factors to group hosts:

	geographic location, purpose, ownership

* TTL