Dynamic Trunking Protocol DTP
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Switch (config)#interface fastethernet 0/1 |
Moves to interface configuration mode. |
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Switch(config-if) #switchport mode dynamic desirable |
Makes the interface actively attempt to convert the link to a trunk link. |
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NOTE: With the switchport mode dynamic desirable command set, the interface becomes a trunk link if the neighboring interface is set to trunk, desirable, or auto. |
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Switch(config-if) |
Makes the interface able to convert into a trunk link. |
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NOTE: With the switchport mode dynamic auto command set, the interface becomes a trunk link if the neighboring interface is set to trunk or desirable. |
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Switch(config-if) |
Prevents the interface from generating DTP frames. |
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NOTE: Use the switchport mode nonegotiate command only when the interface switchport mode is access or trunk. You must manually configure the neighboring interface to establish a trunk link. |
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Switch(config-if) #switchport mode trunk |
Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link. |
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NOTE: With the switchport mode trunk command set, the interface becomes a trunk link even if the neighboring interface is not a trunk link. |
TIP: The default mode is dependent on the platform. For the 2960, the default mode is dynamic auto.
TIP: On a 2960 switch, the default for all ports is to be an access port. However, with the default DTP mode being dynamic auto, an access port can be converted into a trunk port if that port receives DTP information from the other side of the link if that side is set to trunk or desirable. It is therefore recommended to hard-code all access ports as access ports with the switchport mode access command. This way, DTP information will not inadvertently change an access port to a trunk port. Any port set with the switchport mode access command ignores any DTP requests to convert the link.
Continue reading here: Extended System ID
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