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STP and Stacking

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Wanda_5
Frequent Advisor

STP and Stacking

hi,
are there any implications if i configure Spanning Tree Protocol on stacked switches? are there any issues regarding the implementation of these two features of HP Procurve Switches?

Thanks a lot!
3 REPLIES
Mikis Eminov
Occasional Advisor
Solution

Re: STP and Stacking

I think, this features widly independed from each other. And you may concatenate them in varios combo.

Re: STP and Stacking

Hi
HP Procurve Support Stacking as following:
single IP address management for a virtual stack of up to 16 switches, including the ProCurve 2500 series, 2600 series, 2800 series, 3400cl series, 4000m, 6108, 8000m, and 4100gl series

Stacked Switchs appears in the topology as one huge switch with huge amount of ports, It has one IP Address, so I dont see any problem of enabling STP on HP Procurve stacked switchs, and it DOSE Support both of them

Regards
André Beck
Honored Contributor

Re: STP and Stacking

Mohammed,

> single IP address management for a virtual
> stack of up to 16 switches

Yep, that's what they call "stacking" - and AFAIK that's it. A managementwise clustering of a bunch of switches to make them available with a single address and - as this causes loss of individuality in SNMP queries - a way to access SNMP information on individual switches using modified communities, or by merging the MIB views. If I'm wrong here and HP stacking does something fundamentally different from Cisco clustering, please correct me. The basic thing is that it is no stacking in the actual sense of the word - there is no unification of the switches into a greater single 802.1D bridge entity. Real stacking feels exacty like a modular chassis switch that gets further blades plugged into it - just with cables instead of a chassis. See the old Accton design OEMed by half the vendors in the world, see Cisco 3750 stackwise. A real stack is one single bridge hop, as the stack merges *backplanes*, it is no interswitch link.

> Stacked Switchs appears in the topology as
> one huge switch with huge amount of ports,

In which topology? In the real topology it doesn't change a bit, there is still a number of individual 802.1D bridges with all the accompanying effects. It might appear as a compound in some management frontend, but it doesn't create a compound in the actual topology. Meshing on the other hand does indeed create a compound that interfaces to the outside only with STP and should be considered a single 802.1D entity for non-meshers (however it still involves multiple hops), but AFAIK stacking is simply a way to organize management with less IP addresses. It doesn't gain you anything beyond that. It has no effect on L2 or L1.

> It has one IP Address, so I dont see any
> problem of enabling STP on HP Procurve
> stacked switchs, and it DOSE Support both
> of them

Yep, clearly. You still got a bunch of individual 802.1D bridges, so you will need to make sure loops in the physical topology are worked around. As soon as you use L1/L2 redundancy, you *must* combine stacking with (R)STP, else you go cyclotron frame accelerator blinkenlights promptly.

Correct me if I'm wrong,
Andre.