VLAN Setup vs. Unintentional Downtime question

[Fadibitz]

Hey All.

I've got a ProCurve 4108GL and I will be implementing VLANs in the future.

If I were to configure (as an example) port 1 to be a trunk, set it to use VLAN 200, and leave it untagged, would that cause any interruption in the connection to the native VLAN devices already connected? That is to say, would the act of making that change cause a momentary loss of connection as the config is applied?

Thanks.

 

[cajuntank]

None that I've ever seen. I'm assuming your usage of the term "trunk" in your question is actually that you are "tagging" the port for VLAN 200. So port 1 will be tagged for VLAN 1 (default) and VLAN 200. "Trunking" in HP IOS is combining of more than 1 port to form a group so that multiple NIC connections can be used for failover and load balancing. HP "Trunking" would indeed interupt connection while being built.

As a side note, the VLAN 200 would need to be defined and need to be tagged on the port at the other switch being connected.

Hope that helps.

 

[Fadibitz]

Thanks man.

I didn't think there was a problem with it, but you can probably tell by the fact that I used "trunk" in the Cisco sense that I don't play with HP all that much. Looks like there may be nomenclature diffs with dot1Q tagging, as well.

At any rate, this info will help me define the required order of ops.

 

[VinceWhirlwind]

I think you will get an interruption because you need to edit both sides of the trunk to make them match - as soon as you change the far end to VLAN1 tagged/VLAN200 untagged you will lose connectivity until you've reconfigured the near end to match and then spanning-tree and/or LACP will frig with the port for maybe 30 seconds before bringing it back up.

 

[Fadibitz]

Yep, that's true. Fortunately a lot of the configuration will occur on ports that are currently unused (e.g. between the switches and new APs); there are only a few inter-switch trunks that need to be configured. (We're very, very small.)

Thanks, guys! If you think of anything else, I'm definitely listening.

 

[VinceWhirlwind]

Temporarily removing link aggregation config and enabling rapid spanning-tree could be a good move.

You should avoid using untagged VLANs altogether, if you can, on trunk links.

 

[cajuntank]

You will have no interuption on VLAN 1. Again, VLAN 1 is always "tagged" by default on every port to pass down to other switches (its a default so its not going to show up in the config like when you tag for another VLAN). I do this quite often and never have had a blip come up. Now, for the new VLANs created and thus manual tagging of the port(s), since those didn't ever exist and are being created, that traffic will not operate until all pieces are done (which would be expected)... but the default VLAN 1 always exists, thus always operational by default.

 

[VinceWhirlwind]

I think it's fairly certain he currently has VLAN 1 untagged on his switch to switch links.

His VLAN port assignment table will look like this:

Switch Configuration - VLAN - VLAN Port Assignment

Port DEFAULT_VLAN | Port DEFAULT_VLAN
---- + ------------ | ---- + ------------
A1 | Untagged | F2 | Untagged
A3 | Untagged | F3 | Untagged
B1 | Untagged | F4 | Untagged
B3 | Untagged | F5 | Untagged
C1 | Untagged | F6 | Untagged
C2 | Untagged | F7 | Untagged
C3 | Untagged | F8 | Untagged
C4 | Untagged | F9 | Untagged
C5 | Untagged | F10 | Untagged
C6 | Untagged | F11 | Untagged
C7 | Untagged | F12 | Untagged
C8 | Untagged | F13 | Untagged

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I think I may have misunderstood his original post, though. I thought he was talking about VLAN 200 being untagged, on rereading it, maybe all he wants to do is add additional VLANs as "tagged", in which case Cajuntank's explanation is correct as long as you change the word "tagged" to "untagged" in his post.