trunking question

saied

i have a question aboutr trunk ports. lets say you have two switches. switch A fa 0/1 cable is connected to a hub. the hub port than connects to the switch B fa 0/1. would these switche ports be in access mode or trunk mode?

jdballinger

I'm not positive, but I'm going to take a stab at this and let one of the more knowledgable folks correct both of us.

A hub is not going to do anything other than flood the incoming traffic out every other port, regardless of what the frame looks like. Consequently, setting the port on the switch to trunk will not have any effect on the way the traffic is handled by the hub. What it WILL do however is allow for a VLAN tag on the frame, which will then be picked up and forwarded accordingly by the other switch if it is a trunked port as well.

I think...

W Stewart

I believe by default, the switch port is going to be in dynamic auto so it's going to be an access port unless something on the other end tries to negotiate a trunk link but this could just be for 2950 switches. Either way, that's going to be the answer at the CCNA level. I believe jdballinger may be correct about the hub as well but I'm no expert either.

iamme4eva

You'd need to set it to trunk.

If it is set to access, then the port will only be in one VLAN.

Example:

If you have VLAN 100 and 200 on switch A, and you set the port to access mode in VLAN 100, then only VLAN 100 traffic will get to switch B. If there are any hosts on VLAN 200 on switch B, they wouldn't be accessible.

If in doubt, fire up packet tracer and give it a go. (If packet tracer does hubs, I can't remember!)

EDIT: If you are only using one VLAN then it doesn't matter.

EDIT 2: W Stewart is right about dynamic mode. It would set it's self to trunk if the other end negotiated a trunk. A hub is basically invisible.