Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Question about Switch


I have some suspect about switch pls suggest me

- I suspect about file config.text in flash mem on switch , this file is the startup-config ? when i delete this file , router will go to setup mode

- Normally when any traffics be forwarded in the same vlan on the switch (such as from port 1 to port 2) , will it be encapsulated by switch ?

- In the theory , switch vtp server mode can send vtp subset advertise but when i tested by connect between two switches , i found the client mode can send subset to server that have lower config rev than client . Can anyone explain me in this situation


Re: Question about Switch

Hi Friend,

If you delete config.text yes it will remove the startup-config. Some old switches go into the startup mode but now new switches not neceaasry will go to the startup mode but once you delete the config and just reload the switch without doing wr mem it will reload with default configs.

When traffic is fwded between same vlan from port 1 to 2 there will be no encapsulation as encapsulation only comes into picture when it passes through the trunk port which carry more than 1 vlan information. But yes when switch comes form pc and reaches the port port vlan id is assisgned to the frame. Port vlan id is the vlan number which is assigned on the port. So the frame is just a frame when it comes out of pc but when it reaches the switchport vlan id is assigned and then it takes the decesion which vlan it belongs to and is fwded to another port based on the mac address and vlan id and once it comes out of the port again the vlan id is removed but yes there will be no encapsulation.

It is not always necessary that only VTP server will update the client. If you insert a switch with VTP client mode with higher revision number it will send an advertisement and VTP server with low revision number will update itself with the vlan information which is there on VTP client switch.



New Member

Re: Question about Switch

Hi Friend

Thank you for your help but i have a little bit question :

- file config,text and file startup-config in the switch is the same file or separate file ?

- the according to said switchport will assigned vlan-id to the layer 2 frame , this meaning is the same the tagging mechanism 802.1q right??

Thanks again

Re: Question about Switch

Hi there,

1. These files are different on the switches, but they contain the same config. When you make some current changes on the switch config it goes to teh config.text and the moment you do a write mem it will get saved in the startup-config. If you delete config.text after write mem, your switch will not go to rommon as it will pickup the config from startup-config gile.

2. Its not the same as the 802.1q tagging that is diffreent from the port vlan ID assigned to a le farme .


-amit singh