spanning-tree port type edge trunk, cli question

[chaejungho]

If I set "edge" without setting "edge trunk" on the trunk port, will not it be fast convergence?

What happens to the spanning tree or link if I change the "edge" configured port to "edge trunk"? (Is there a problem?)

must, do I have to set the "edge" depending on the port type?

[Reza Sharifi]

If the port is configured as access port, it should be just "edge".  If the port is configured as trunk and connected to a server or VM environment with multiple vlans, it should be "edge trunk"

HTH

[chaejungho]

I know that I should set up a " Edge or Edge trunk " in principle.

but If you set the "edge" on the trunk port, is it a problem with spanning tree convergence behavior?

I think that spanning tree convergence will not be a problem even if the switch port has only the spanning tree edge set, regardless of access or trunk.

Note that other vendors only set edges for without identifying the CLI.

is not it? Was I wrong?

[Reza Sharifi]

That should not cause a problem as long as you are not connecting the trunk port to another switch.

PortFast causes a switch or trunk port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states.

You can use PortFast on switch or trunk ports that are connected to a single workstation, switch, or server to allow those devices to connect to the network immediately, instead of waiting for the port to transition from the listening and learning states to the forwarding state.

Caution You can use PortFast to connect a single end station or a switch port to a switch port. If you enable PortFast on a port that is connected to another Layer 2 device, such as a switch, you might create network loops.

more info here;

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4000/8-2glx/configuration/guide/stp_enha.html

HTH

[chaejungho]

The intent of my question is not a functional description of the portfast CLI.

Other vendors do not distinguish edge or edge trunk CLI.

[Rolf Fischer]

If I set "edge" without setting "edge trunk" on the trunk port, will not it be fast convergence?

That's correct:

Switch#conf term
Switch(config)#interface Gi0/1
Switch(config-if)#switchport mode trunk
Switch(config-if)#spanning-tree portfast edge

%Warning: (...)
 Use with CAUTION

%Portfast has been configured on GigabitEthernet0/1 but will only have effect 
when the interface is in a non-trunking mode.

Switch#show spanning-tree int Gi0/1 portfast
VLAN1            disabled

Switch#show spanning-tree int Gi0/1
Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------
VLAN1               Desg LRN 4         128.4    P2p

As we can see, the portfast command without the 'trunk' keyword has no effect on a trunk port and the port has to go through STP Listening and Learning states initially.

However, with the additional "trunk" keyword you can see the difference:

Switch#show spanning-tree int Gi0/1 portfast
VLAN1            enabled

Switch#show spanning-tree int Gi0/1 detail | i portfast
   The port is in the portfast edge trunk mode

I guess the intention was to prevent  accidential misconfigurations on trunk ports.

HTH
Rolf

[darkons]

very helpful, I had exactly the same question and concern since I found trunk ports to ESXi hosts configured just as edge and suspected it would not be in effect