layer 2 broadcasts over trunks and vlans

sjcat

Don't know why I'm thinking of this now before my exam but:

if you have a switch that receives a frame with an unknown destination, it will forward the frame out all interfaces except the one it was received on.

will it also be forwarded out trunk interfaces?
it won't be forwarded out interfaces on vlans other that the vlan it was received on?

I'm a little confused

thanks

mikej412

sjcat wrote: »

will it also be forwarded out trunk interfaces?
it won't be forwarded out interfaces on vlans other that the vlan it was received on?

If the trunk allows that VLAN, then the frame with the unknown destination will go out the trunk port as well.

Remember that VLANs are their own broadcast domain -- so it will only be flooded out the ports (or trunks) that are configured for that VLAN.

sjcat

fantastic, thanks for the quick answer, that puts my mind at ease.

ncsugrad2002

yep, that's how it works. it'll go out ports for that VLAN + trunk ports which more or less are all VLAN's by default