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In the vlan settings on the D-Link DGS3100-24 there is a default vlan with id 1 with settings to "Untag VLAN Ports" T1-T32.

All other vlans user port 1-24 in their settings and the switch only have 24 physical ports.

What is port T1-T32, why are they there and what are they used for? It's not mentioned in the manual at all (or I'm blind).

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The device supports up to 32 802.3ad Link Aggregation groups. These ports are probably for these groups.

I guess the T means Trunk, which is the term used for aggregated ports in lower-cost switches nowadays (not that I want to do down these switches!). In the old days, a Trunk port was a port using tagged frames.

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I think you're correct. There are 32 static trunks defined from start with no ports attached to them. It's still a weird way to handle it though. No explanation what so ever what the T* ports are in the VLAN view. The trunks are just named 01-32 in the Trunk view. – Molotch May 29 '12 at 14:04

T1-T32 refers to not a switch port, but a Trunk Group which can consist of various combinations of ports that are interconnecting to other switches on the network.

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Not sure on the port numbers for D-link switches, but Ports as the switch OS refers to them and ports as you see on the physical box are not the same. Generally T1-T24 are going to be your real ports, but it will also refer to any input ethernet as ports, as well as some types of virtual ports.

It's also possible that the text for the setting is used across multiple switches, and there are some 32-port switches that use the same software as your 24-port setting.

Untagging ports means that you pass the traffic out of that port without identifying the VLAN out of it.

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