From: asadovnikov (asadovnikov@comcast.net)
Date: Sat Oct 11 2003 - 02:46:48 GMT-3
The reason you see it all over the practice exercise is that this is a
default mode of the port. In real life many people continue to prefer
manually setting port mode, and most often then not a port connected to a
router would be manually forced to be access port.
However as Ken explained, the default configuration does work. Since a
router will not talk DTP port will stay in access mode (i.e. an attempt to
become a trunk would not ever succeed).
Best regards,
Alexei
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Kenneth Wygand
Sent: Saturday, October 11, 2003 1:27 AM
To: Hunt Lee; ccielab@groupstudy.com
Subject: RE: switchport command
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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