I want to use router-on-a-stick method on cisco 2600 , after creating a sub-interface, can not use "encapsulation" command to define encapsulation method and it's vlan .
How to correct this that can use "encapsulation" command ?
The IOS version is 12.2(3) .
after sub interface
Router (config-subif)# encapsula dot1q (X)-> This should be the VLAN name or Number
Then Ip address
As per Mohamed's post you need to use Feature Navigator. For your version of IOS you need a minimum feature set of IP Plus to support 802.1q encapsulation.
If the command is not available then i suspect your feature set is just IP.
I was test this by the original IOS of my router "c2600-i-mz.122-2.T1.bin" but can't do this and upgrade the IOS to "c2600-io3-mz.122-3" , but also can't. I thik that the IOS don't supprt this feature after test with Cisco Feature Navigator.
I was write the command completely but can't.
You are using IP/FW/IDS feature set. This does not support 802.1q encapsulation. If you want to use 802.1q you will need to change the feature set of your IOS. You can still use 12.2(3) but IP Plus is the minimum to support 802.1q - image file name is c2600-is-mz.122-3.bin.
But you also need to check if you are losing any features by changing the feature set. For a start is there a reason you are running the FW/IDS feature set ie. are you using the firewalling or IDS features ?
This is why using Feature Navigator as suggested by Mohamed is what you need to do.
I'm having a similar issue, my dilemma is that I don't know what feature set I'm running now, or how to choose IP Plus. I tried the Feature Navigator, and it asks me what feature set I'm running now (I don't know.)
My "Show Ver" tells me that I'm running 3600 software (c3620-I-M) Version 12.2(2)T Release Candidate (fc1) but I'm not sure how to proceed from here - I need to identify the correct file to download with IP Plus feature set to be able to implement dot1q encapsulation.
For further info, please check Cisco Feature Navigator: