six router modes

> user mode
# privileged mode
(Config)# global configuration mode
(config-if) sub configuration modes
	interface
	sub interface mode
	line vty
	line con
	router
	route-map
	class-map
	...
?[yes/no]:	setup mode
RxBoot

Duplex match
1. By default, when autonegotiation fails, the Catalyst switch 
sets the corresponding switch port to half-duplex mode. 
2. If the device is manually configured to operate in 
half-duplex mode, it matches the default mode of the switch.
3. If the other party is set to full-duplex, problem happens!!
4. therefore, be carefull about manually setup --> they have to match!