From: Kenneth Wygand (KWygand@customonline.com)
Date: Sat Oct 11 2003 - 02:26:32 GMT-3
Lee,
Yes, "switchport mode dynamic desirable" tells the port to send DTP frames (Dynamic Trunking Protocol) to the other switch requesting that a trunk be dynamically setup. If the other side is listening to DTP packets (set to AUTO or DESIRABLE), the trunk will form. Also, if the other side is set to ON, it will not use the DTP packets but will automatically be a trunk because it's "nailed on" at the remote end.
Once the port becomes a trunk, the "switchport access vlan 120" command has no effect. If the switchport does NOT become a trunk, it will be an access port on vlan 120.
The configuration you've provided essentially says "Try to become a trunk port which will forward all VLANs by default... if you cannot become a trunk port, you will be an access port - if you do in fact become an access port, operate on VLAN 120". It's sort of a fallback, for lack of a better term.
Am I clear in my explanation? If not, please let me know and I'll elaborate further.
Thanks!
Ken
-----Original Message-----
From: Hunt Lee [mailto:hunt_lee@bigpond.net.au]
Sent: Sat 10/11/2003 12:29 AM
To: ccielab@groupstudy.com
Cc:
Subject: switchport command
Hi Group,
Can someone please explain to me when one will use the following command?
int fa0/6
switchport access vlan 120
switchport mode dynamic desirable
And on my practice exerices, they pretty much use these on all the switchports, including ones that are for connecting to routers and workstations.
What I don't understand is, isn't the dynamic desirable command will get the switchport to try to neogotatie and become a trunk? If it is the case, why using it with switchport access vlan command ?
And when would you use the switchport mode dynamic desirable command?
Any help would be greatly appreciated.
Lee
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