cdp/dtp/pagp/vtp

CDP= Cisco Discovery Protocol

• Encapsulation:              802.3 : 802.2 - SNAP HDLC
• Protocol Type Code:     0x2000
• Multicast Address:        01:00:0C:CC:CC:CC
• Timer:                         60 sec
• Holdtime:                    180 sec

DTP = Dynamic Trunking Protocol

• Encapsulation:              802.3 : 802.2 - SNAP HDLC
• Protocol Type Code:     0x2004
• Multicast Address:        01:00:0C:CD:CD:CD
• 802.1Q                        Sent on the Native Untagged VLAN
• ISL                             Sent encapsulated as VLAN 1

DTP Modes, Combinations and Configuration Example

Access (Off)
         sw1 (config-if) switchport mode access

• Puts the interface into permanent nontrunking mode and negotiates to convert the link into a nontrunking link. The interface becomes a nontrunk interface even if the neighboring interface does not change.

Dynamic Auto
         sw1 (config-if) switchport mode dynamic auto

• Makes the interface convert the link to a trunking link if the neighboring interface is set to trunk or desirable mode. This is the default mode for all Ethernet interfaces.

Dynamic Desirable
         sw1 (config-if) switchport mode dynamic desireable

• Makes the interface actively attempt to convert the link to a trunking link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode.

Trunk
         sw1 (config-if) switchport mode trunk

• Puts the interface into permanent trunking mode and negotiates to convert the link into a trunking link. The interface becomes a trunk interface even if the neighboring interface does not change.

Nonegotiate (Access)
         sw1(config-if) switchport nonegotiate
         sw1(config-if) switchport mode access

• Puts the interface into permanent access mode but prevents the interface from generating DTP frames. You must configure the neighboring interface manually as a access interface to make sure you establish a usable access link.

Nonegotiate (Trunk)
         sw1(config-if) switchport nonegotiate
         sw1(config-if) switchport mode trunk

• Puts the interface into permanent trunking mode but prevents the interface from generating DTP frames. You must configure the neighboring interface manually as a trunk interface to make sure you establish a usable trunking link.

DTP Modes	access (off)	dynamic auto	dynamic  desirable	trunk (on)	nonegotiate (access)	nonegotiate (trunk)
access (off)	static access	static access	static access	unexpected results	static access	unexpected results
dynamic auto	static access	static access	trunk	trunk	static access	unexpected results
dynamic desireable	trunk	trunk	trunk	trunk	static access	unexpected results
trunk (on)	unexpected results	trunk	trunk	trunk	unexpected results	trunk
nonegotiate (access)	static access	static access	static access	unexpected results	static access	unexpected results
nonegotiate (trunk)	unexpected results	unexpedted results	unexpected results	trunk	unexpected results	trunk

PaGP = Port Aggragation Protocol

 

UDLD = Unidirectional Link Detection

•  

VTP = VLAN Trunking Protocol

• triggered update
• every 5 minutes / 300 seconds

Created by Patrick Basso -- IP, Therefore I Am

本文转自:http://www.ubernet.us/8.html

Mode	Description
on	Mode that forces the LAN port to channel unconditionally. In the on mode, a usable EtherChannel exists only when a LAN port group in the on mode is connected to another LAN port group in the on mode. Because ports configured in the on mode do not negotiate, there is no negotiation traffic between the ports. You cannot configure the on mode with an EtherChannel protocol. If one end uses the on mode, the other end must also.
auto	PAgP mode that places a LAN port into a passive negotiating state, in which the port responds to PAgP packets it receives but does not initiate PAgP negotiation. (Default)
desirable	PAgP mode that places a LAN port into an active negotiating state, in which the port initiates negotiations with other LAN ports by sending PAgP packets.
passive	LACP mode that places a port into a passive negotiating state, in which the port responds to LACP packets it receives but does not initiate LACP negotiation. (Default)
active	LACP mode that places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending LACP packets.