20040324 Topics:
Spanning Tree Protocol (STP)
	One root bridge per network 
	One root port per non root bridge 
	One designated port per segment 
	Unused, non-designated ports 
1. Broadcast storms (broadcast) 7.1.4 & 7.2.1
2. MAC table instability (unicast)
3. BPDU 7.2.2 e-lab
4. STP steps:
   (1) identify the root bridge (BID= priority + ID)
   (2) Blocking 20s: receive BPDU only
   (3) Listening 15s: select best  path to root
   (4) Learning 15s: create MAC table
   (5) Forwarding
5. IEEE 802.1W:
   point-to-point link => to forwarding immediately
   edge-type => back to normal immediately
   shared-link

Virtual LAN (VLAN)
keywords
1. Logically grouped (1,2,5) (3,4,6) (rest)
2. create broadcast domain
3. increase security

static = manually assign (group/separate ports)
dynamic = based on MAC, etc, need a server

VTP: Virtual Trunk Protocol
public (IETF): frame tag (802.1Q)
Cisco: ISL (Inter Switch Link)


OSPF cost = 10Mbps/bandwidth ?