Switch won't encapsulate! Help!

Unanswered Question
Sep 13th, 2007

When I try and do some basic encapsulation functions on my new switch, it won't allow it; in fact, it doesn't even give the option at the "?" option where it should exist. I can't do VLANs and set trunking to the router. Can someone assist? Someone had told me that I just needed to update flash or something. If so, I could use some advice. Below is the output of "show version":

Cisco Internetwork Operating System Software

IOS (tm) C2900XL Software (C2900XL-HS-M), Version 11.2(8.10)SA6, MAINTENANCE INT


Copyright (c) 1986-1902 by cisco Systems, Inc.

Compiled Fri 15-Feb-02 09:47 by devgoyal

Image text-base: 0x00003000, data-base: 0x0020E278

ROM: Bootstrap program is C2900XL boot loader

Switch uptime is 10 minutes

System restarted by power-on

System image file is "flash:c2900XL-hs-mz-112.8.10-SA6.bin", booted via

cisco WS-C2924C-XL (PowerPC403GA) processor (revision 0x11) with 4096K/640K byte

s of memory.

Processor board ID 0x09, with hardware revision 0x00

Last reset from power-on

Processor is running Enterprise Edition Software

Cluster member switch capable

24 Ethernet/IEEE 802.3 interface(s)

32K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address: 00:90:B1:91:8B:80

Motherboard assembly number: 73-2911-06

Motherboard serial number: FAA02359GZE

System serial number: FAA0237W09A

Configuration register is 0xF


I have this problem too.
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Kevin Dorrell Thu, 09/13/2007 - 05:20

Could you post a terminal log of what happens if you do:

conf t

int f0/1

switchport mode trunk

switchport trunk encap?

Kevin Dorrell


crunchyhippo Thu, 09/13/2007 - 05:45

I can, but I'll have to wait until tonight - about eight or nine more hours from now.

paul.matthews Fri, 09/14/2007 - 02:27

As Kevin says, a log of the output would be helpful. My first comment may be less so :-(

The 2924XL is now an obsolete switch, and support will be difficult to obtain, so really you should be looking at upgrading. They are OK for a little playing in a lab, but even for that they are an early IOS based switch and do not support quite a few of the newer features.

Having said that, 2900XLs do support VLANs and trunking, but IIRC they only support one mode - I can't remember if they support ISL or dot1q. It may be that only supporting he one mode may be causing your confusion.

Kevin Dorrell Fri, 09/14/2007 - 03:18


Surprisingly, the 2900XL supported both isl and dot1q, but the (later) 2950-12 supported dot1q only. So the 2950 has no switchport trunk encapsulation command. For me, that was the big red flag that said the days of ISL were numbered.

Kevin Dorrell



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