Trunk encapsulation command not available

Mar 19, 2006 4 Replies

I am trying to set up a trunk port with DOT1Q encapsulation - but in config mode I don't get the option to set any encapsulation; any suggestions - see below:



Switch(config-if)#switchport trunk ? allowed Set allowed VLAN characteristics when interface is in trunking mode native Set trunking native characteristics when interface is in trunking mode pruning Set pruning VLAN characteristics when interface is in trunking mode



Switch#show ver Cisco Internetwork Operating System Software IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(14)EA1



I think to set the port to trunk it's simply switchport mode trunk then to set the encasulation to dot1q it's encap dot1q

In fact if memory serve me correctly the 2950's only support dot1q and the 1900's only supported ISL (CCNA test topics!) It's only the Catalyst's that support both No idea why this is the case!

you might not be able to "set" 802.1Q mode if that is all there is - do a "show interface" or show switchport (cat 6ks, so i dont use 2950s) once you have configured a port and you should get the mode info.

AFAIR the ref to "native" means 802.1Q is supported, since there isnt anything equivalent on ISL.

probably a limitation of a chipset used - higher end cisco gear uses their own chips so more likely that they build in support for the proprietary ISL format.

>

"Ned" skrev i en meddelelse news: snipped-for-privacy@j33g2000cwa.googlegroups.com...

Since the 2950 only support dot1q there is no need for setting encapsulation at the command line.

labcat2950(config-if)#switchport trunk ? allowed Set allowed VLAN characteristics when interface is in trunking mode native Set trunking native characteristics when interface is in trunking mode pruning Set pruning VLAN characteristics when interface is in trunking mode

labcat2950(config-if)#switchport mode labcat2950(config-if)#switchport mode ? access Set trunking mode to ACCESS unconditionally dynamic Set trunking mode to dynamically negotiate access or trunk mode trunk Set trunking mode to TRUNK unconditionally

Chris.

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