Spanning Tree Port Priority

Aug 31, 2005 3 Replies

In my configuration report of my HP 4000m Procurve switch there lists a section for Spanning Tree Operation, then a listing of ports and a priority number. I just barely understand this end of IT, but realize a lower number represents higher priority. However, if my config report states Spanning tree is not enabled, do these priority numbers matter? All but one are set at 128, and one is at 64. (Follow up questions to come if this matters despite STP being disabled)



Any good online referrences to explain this stuff to me better? The HP management and config guide doesn't help me much.



Thanks- Brian


You can go to the IEEE web site and download 802.1D. Find the getieee button to do this.

In IEEE 802.1D, Clause 17 discusses the Rapid Spanning Tree Protocol, and refers back to Clause 9 for a discussion of the priority bits. These priority bits are part of the overall Switch ID (64 bits) and Port ID (16 bits). By configuring the priority bits, a network administrator can encourage the RSTP to use certain switches and data paths preferentially.

However, I don't know where HP finds enough bits for 128 levels. The IEEE standard mentions 3 or 4 bits assigned specifically to priority, not 7 bits.

Anyway, I would think that if RSTP is disabled, then how these bits are set should not matter.

Bert

Spanning Tree port priorities don't have any effect if the Spanning Tree Protocol entity itself is disabled.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

Thanks guys, that's kind of what I thought, but being a newb to this end of the spectrum, had to ask.

Thanks! Brian

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