generateDTP frames. Use theswitchport trunk encapsulation dot1q interface to select the encapsulation
typeon the trunk port.
Youcan also specify on DTP interfaces whether the trunk uses IEEE 802.1Q encapsulation or if the
encapsulationtype is autonegotiated. The DTP supports autonegotiation of IEEE 802.1Q trunks.
Layer 2 Interface Modes
Table 10: Layer 2 Interface Modes
FunctionMode
Putsthe interface(access port) into permanent
nontrunkingmode and negotiates to convert the link
intoa nontrunk link. The interface becomes a
nontrunkinterface regardless of whether or not the
neighboringinterface is atrunk interface.
switchportmode access
Makesthe interface able to convert the link to a trunk
link.The interfacebecomes a trunk interfaceif the
neighboringinterface is setto trunk or desirable
mode.The default switchport mode for all Ethernet
interfacesis dynamic auto.
switchportmode dynamic auto
Makesthe interfaceactively attempt to convert the
linkto a trunk link.The interface becomes a trunk
interfaceif the neighboringinterface is set to trunk,
desirable,or auto mode.
switchportmode dynamic desirable
Putsthe interface into permanent trunking mode and
negotiatesto convert the neighboring link into a trunk
link.The interfacebecomes a trunk interface even if
theneighboring interfaceis not a trunkinterface.
switchportmode trunk
Preventsthe interfacefrom generating DTP frames.
Youcan use this command only when the interface
switchportmode is accessor trunk. You must
manuallyconfigure the neighboringinterface as a
trunkinterface to establish a trunk link.
switchportnonegotiate
Configuresthe interfaceas a tunnel (nontrunking)
portto be connected in an asymmetric link with an
IEEE802.1Q trunk port. The IEEE 802.1Q tunneling
isused tomaintain customer VLAN integrityacross
aservice provider network.
switchportmode dot1q-tunnel
Configuresthe private VLAN mode.
The switchportmode private-vlan
commandoption is notsupported.
Note
switchportmode private-vlan
Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1
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Configuring VLAN Trunks
Layer 2 Interface Modes