From: Anthony Sequeira (terry.francona@gmail.com)
Date: Sat May 07 2005 - 09:43:47 GMT-3
Yes - you are right on here - the switchport mode access command
unconditionally sets the port to be an access port. This would prevent
you from trunking.
Here is a lab scenario I just set up - DSW1 and DSW2 are connected via
their Gi 0/9 ports - and they are trunking by default thanks to the
default mode of dynamic desirable. In fact - it is an ISL trunk that
they have formed automatically (sure wish they would negotiate 802.1q
instead!).
On DSW1 I issue the command switchport access vlan 20 - and really
nothing happens because trunking is still being negotiated. Here is
the verification:
DSW1#show int gi 0/9 switch
Name: Gi0/9
Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: trunk
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: isl
Negotiation of Trunking: On
Access Mode VLAN: 20 (VLAN0020)
...
Now - if I try the switchport mode access command as well - things do
in fact change! As you can see - no more trunk - even though DSW2 is
trying very hard to still form one.
DSW1#show int gi 0/9 switch
Name: Gi0/9
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
Negotiation of Trunking: Off
Access Mode VLAN: 20 (VLAN0020)
...
In the lab - to save time - I plan on just using the command
switchport access vlan XX unless the instructions force me to do
otherwise. This is because I do not need to worry about a switch being
on the other end of the connection and negotiating a trunk! In the lab
- it is going to be routers on the other end of the access ports for
sure.
HTH,
Anthony Sequeira
On 5/7/05, Hotmail <pauwen@hotmail.com> wrote:
> Hello group,
>
> the command 4switchport mode trunk4 is used to prevent a port from reverting
> to access mode when trunk negotitaion fails. Does it work the other way around
> as well, that is, a switchport configured in 4switchport mode access4 can
> never revert to being a trunk port ? The reason I am asking is that I have
> seen configurations like this:
>
> interface FastEthernet0/1
> switchport access vlan 3
>
> and this:
>
> interface FastEthernet0/1
> switchport mode access
> switchport access vlan 3
>
> Is the difference that in the first configuration, the port could still revert
> to being a trunk port, while in the second, it cannot ?
>
> Thanks for your help in advance.
>
> GP
>
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