CDP= Cisco Discovery Protocol
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Encapsulation: 802.3 : 802.2 - SNAP HDLC
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Protocol Type Code: 0x2000
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Multicast Address: 01:00:0C:CC:CC:CC
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Timer: 60 sec
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Holdtime: 180 sec
DTP = Dynamic Trunking Protocol
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Encapsulation: 802.3 : 802.2 - SNAP HDLC
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Protocol Type Code: 0x2004
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Multicast Address: 01:00:0C:CD:CD:CD
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802.1Q Sent on the Native Untagged VLAN
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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 |
dynamic |
dynamic |
trunk |
nonegotiate |
nonegotiate |
access |
static |
static |
static |
unexpected |
static access |
unexpected |
dynamic |
static |
static |
trunk |
trunk |
static |
unexpected |
dynamic |
trunk |
trunk |
trunk |
trunk |
static |
unexpected |
trunk |
unexpected |
trunk |
trunk |
trunk |
unexpected |
trunk |
nonegotiate |
static |
static |
static |
unexpected |
static |
unexpected |
nonegotiate |
unexpected |
unexpedted |
unexpected |
trunk |
unexpected |
trunk |
PaGP = Port Aggragation Protocol
UDLD = Unidirectional Link Detection
VTP = VLAN Trunking Protocol
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triggered update
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every 5 minutes / 300 seconds
本文轉自:http://www.ubernet.us/8.html