Nortel unregistered Frames

[alphahelix3]

Sorry for this stupid and quite noobish question but I have no way to test for myself all of our switches are in production (and full) nothing lying around to test on and the documentation (nortel pdf's) or any forums I've searched really doesn't clarify completely so here goes.

On a nortel switch 4550-PWR with all the ports set to vlan 1, pvid 1, filter-untagged disabled and filter-unregistered disabled. This switch is isolated for this example. How would the switch treat a packet tagged for vlan 7? Lets make it a broadcast packet just to make things simple. Since Vlan 7 does not exist will the packet cease to exist or will the switch pass in it on vlan 1 untagged and broadcasted on all vlan 1 member ports.

The backstory to this is a co-worker made the comment that a nortel switch in the above configuration with 2 devices set to tag or as he put it "the devices are told which vlan they are on" would communicate with each other. Since I have no way to test or any docs with a definative answer. (mostly what I get is filter-unregister frames either passes or drop frames depending on whether or not the tag matches the membership of the port. Great! where does frame go after that?) A part of me says that the frame doesn't go anywhere as that vlan doesn't exist but this is all a guess at the moment any clarification would be greatly appreciated

 

[anthonyanderberg]

That's not a noobish question - that's a really interesting question (that a noob wouldn't think about!)

A couple years ago we had a discussion about the inDiscard and inError counters relating to this same kind of question, and I have to say I'm not sure what the 'correct' behavior is.

I couldn't see the switch treating vlan 7 as an isolated vlan with the configuration listed, although it could dump packets into vlan 1 - but of course tagged packets aren't really valid frames in a completely untagged port... Does anyone have experience with this beyond my wild speculation?

 

[VinceWhirlwind]

If the frame is tagged for VLAN7, and the switch has no ports in VLAN7 and has no VLAN7 configured on it even, the frame can't get onto the switch in the first place.

 

[mathews84]

First of all a tagged and untagged port will not communicate.so if there is no tagged port on the switch then the switch will not forward any packet at all.next if the port is tagged with vlan 7 on 1 switch then the other switch will also need a tagged port with the same vlan no 7.