HP Switching, DT Links to two STP switches

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I'm quite new to HP networking and have inherit a setup with HP 8200 switches connected using DT-LACP trunks.

Our project right now is to connect two switches from another datacenter to these two 8200 DT switches..

So, datacenter A uses 8200 switches (switch A & B)
Datanceter B uses random Procurve (switch E&F)

Switch E&F has STP activated and uses a trunk between them currently)

If I connect switches E&F to Switch A&B, won't it cause a loop? Since HP DT disables on the 8200 switches.

In other words

Switch E connects to Switch A
Switch F connects to switch B

Switch E&F has a redundancy trunk between them..

Having hard time finding documentation regarding this..would appreciate all the help I can get!

Thanks

Best Answer

This isn't Distributed Trunking. The described topology is:

.-------.  .-------.
|       |  |       |
| 8200A |--| 8200B |
|       |  |       |
'-------'  '-------'
    |          |
    |          |
.-------.  .-------.
| sw e  |--| sw f  |
'-------'  '-------'

Since it's said that the 8200s are connected with "DT-LACP trunks" I assume the Inter-switch link required for DT is present between them. If these links are in the same VLAN and STP is not enabled, there is a loop.

This is what Distributed Trunking looks like:

.-------.  .-------.
|       |  |       |
| 8200A |--| 8200B |
|       |  |       |
'-------\  /-------'
    |    \/    |
    |    /\    |
.-------/  \-------.
| Sw E  |  | Sw F  |
'-------'  '-------'

The links on 8200s are configured for Distributed Trunk, and the link between them as Switch Interconnect link which makes the downlinks to each edge switch appear as one logical link. The uplinks on switches E and F are aggregated with LACP so each of them will see one logical link as well. There is no loop.

If there's a redundant link between switches E and F and it's in the same VLAN as the uplinks, a loop will form. STP is needed to counteract that, and root and path priorities must be configured so that STP blocks the redundant link.

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