Talk:Spanning Tree Protocol/Archive 1

Backwards
It was stated that STP was from the 802.1w conference while RSTP was from the 802.1d conference. This is actually backwards. RSTP is 802.1w and STP 802.1d. Check for yourself, Cisco Press CCNA ICND book for the 640-811 exam. pg. 36.
 * No idea what you're blabbering about. Don't polute this talk page with irrelevant nonsense.
 * He's correct, your polluting by posting about a subject you don't know about —The preceding unsigned comment was added by Charfles (talk • contribs) 06:14, 9 February 2007 (UTC).

There seems to be part of the text duplicated in the first paragraph: "The spanning tree network protocol provides a loop free topology for any bridged LAN. The Spanning Tree Protocol, which is also referred to as STP, is defined in the IEEE Standard 802.1D. [...] STP is used in switched networks to prevent loops, and has been standardized by IEEE 802.1D. " The last sentence is already completely included in the first two. Could it be removed ? MJost 14:31, 12 December 2006 (UTC)

Has been done already. Mauro Cicognini 12:42, 12 July 2007 (UTC)

Merge (BPDU)
I recommend that the BPDU article be merged into the BPDU section of this article. Any thoughts on this? 131.230.53.188 01:08, 11 May 2007 (UTC)
 * The other option is to create a separate page for BPDU - have a one liner on BPDU here and reference that. am dealing with this issue right now on some of the Ethernet articles, however. What size is too big? this article is pretty big. and How do you keep people from rewriting the BPDU article?  Sorry I cant help with much opinion, but more questions--Boscobiscotti 06:27, 12 May 2007 (UTC)
 * Second thought - It should be merged. integral to understanding--Boscobiscotti 19:24, 12 May 2007 (UTC)
 * It should be merged and redirected. It is thrown out of context in a standalone article. Kremso 06:47, 21 May 2007 (UTC)

I think that the BPDU article should be moved into the BPDU secion of the STP article due to the importance that BPDU's have in the Spanning Tree process. It is an integral part and having it in the STP article would be very beneficial.

(New comment, the above is anon) Definitely merge, BPDU's don't exist outside of STP and as already mentioned are integral in the protocol. Ngriffeth 14:43, 3 July 2007 (UTC)

Let's just go ahead and merge it, and provide a redirect on the old BPDU page... Mauro Cicognini 12:43, 12 July 2007 (UTC) ... done. Mauro Cicognini 13:09, 12 July 2007 (UTC)

Explaining paragraph move from end of introduction to "evolution"
I moved the mention of DEC STP and interworking issues down to the evolution section; also added references to the standards documents and to one of the Cisco manuals that explains a problem with interworking of DEC and IEEE STP. Ngriffeth 17:25, 12 September 2007 (UTC)

Removed poetical section - non encyclopic?
I removed an entire section from the article because it seems to me to be non-encyclopedic. Here is the original text for archival purposes:

BEGIN ORIGINAL TEXT

Radia Perlman, the inventor of the algorithm, summarized it in a poem titled "Algorhyme" (adapted from "Trees", by Joyce Kilmer):


 * I think that I shall never see
 * A graph more lovely than a tree.
 * A tree whose crucial property
 * Is loop-free connectivity.
 * A tree which must be sure to span
 * So packets can reach every LAN.
 * First the Root must be selected
 * By ID it is elected.
 * Least cost paths from Root are traced
 * In the tree these paths are placed.
 * A mesh is made by folks like me
 * Then bridges find a spanning tree.

You can listen to the author of STP playing on piano and her daughter Dawn Perlner (voice) performing at MIT's Lincoln Laboratory, a musical version of the poem, set by the author's son Ray Perlner, which can be downloaded from NetworkWorld Podcasts Section.

END ORIGINAL TEXT

Triddle 00:38, 29 September 2007 (UTC)

bad choices
do real spanning tree implementations have stuff built in to prevent bad choices (e.g. using a 100 megabit link that some luser connected by plugging a patch cable between two wallports when a gigabit one is availible) or to prevent massive performance changes if a dead switch is replaced? Plugwash 17:31, 29 April 2006 (UTC)

I was loking for STP concerning Layer 2 and was not aware of something like Rapid STP. The search brought me sraight to RSTP which proved to be an enlightenment and motivation to further learn the subject. 117.199.192.108 (talk) 19:22, 26 July 2008 (UTC)yash Pal Jagia

More instructive and specific than loop-free 2 words alternating or augmenting, if you like call method path with no cycles —Preceding unsigned comment added by Implements (talk • contribs) 14:14, 13 June 2010 (UTC)

Not an OSI protocol
The first sentence is highly misleading as STP is not an OSI protocol at all. I suggest to reword it to reflect that if described by the OSI model then STP falls into the data link layer. --Pgallert (talk) 10:23, 6 February 2009 (UTC)
 * Agree ; I've removed the reference to the data link layer as dubiously helpful. Skandha101 • 19:47, 29 July 2011 (UTC)

Brocade PVST and Cisco PVST
I've removed a clause saying that Brocade supports PVST. It is probably untrue that all Brocade products support PVST, but more importantly, I cannot confirm that the Brocade PVST is the same as the proprietary PVST described in the wikipedia article, or that it interoperates with Cisco. The source listed says nothing about Cisco. Original line: Both PVST and PVST+ protocols are Cisco proprietary protocols and they cannot be used on most 3rd party switches, although Brocade supports PVST Skandha101 • 19:42, 29 July 2011 (UTC)

Actually, Brocade (Foundry) switches support PVST+ and interoperate with PVST. Per the "Brocade MLX Series and NetIron Family Configuration Guide, r05.2.00b"...

PVST or PVST+ compatibility

Brocade’s support for Cisco’s Per VLAN Spanning Tree plus (PVST+) allows the Brocade device to run multiple spanning trees (MSTP) while also interoperating with IEEE 802.1Q devices1. Ports automatically detect PVST+ BPDUs and enable support for the BPDUs once detected. When it is configured for MSTP, the Brocade device can interoperate with PVST.

Overview of PVST and PVST+

Per VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that allows a Cisco device to have multiple spanning trees. The Cisco device can interoperate with spanning trees on other PVST devices but cannot interoperate with IEEE 802.1Q devices. An IEEE 802.1Q device has all its ports running a single spanning tree. PVST+ is an extension of PVST that allows a Cisco device to also interoperate with devices that are running a single spanning tree (IEEE 802.1Q). The PVST+ support allows the Brocade device to interoperate with PVST spanning trees and the IEEE 802.1Q spanning tree at the same time.

Similar language appears in the "FastIron Configuration Guide, 07.3.00"

Hank Massey (BCNE, CCNA) — Preceding unsigned comment added by Hjmassey (talk • contribs) 22:28, 24 January 2012 (UTC)

STP Port Status Times
It doesn't mention that the time each port stays in each status for. Blocking 20sec, Listening 15sec, Learning 20sec. 09:46, 15 May 2014 (UTC) — Preceding unsigned comment added by 220.244.105.200 (talk)

SSTP: Single Spanning Tree Protocol
My new Brocade switches support something called Single Spanning Tree Protocol. I don't see any information about that here. It appears to break links on our Cisco Catalyst 6500 router whenever it detects a new device. Yakatz (talk) 00:40, 11 June 2015 (UTC)

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intermittent failures
How would (fast) spanning tree protocol react on intermittent failures? As far as I understand intermittent failures will lead to frequent changes in the routing. Can permanent changes be somehow configured to not re-rely on often failing routes? I suppose not. --Sebastian.Dietrich (talk) 09:34, 29 November 2018 (UTC)


 * That depends on the failure – a link failure (link down) or a link up event causes a reselection of forwarding ports. Frequent transmission failures cause nothing. If you're using STP alone there's little you can do, but some devices have policies governing (too) frequent changes. Note that the term "routing" is used for layer-3 forwarding, layer-2 forwarding is called "bridging" or "switching". (Of course, layer-2 changes may cause dynamic routes to change subsequently, but usually STP failover is invisible to layer 3.) --Zac67 (talk) 17:53, 29 November 2018 (UTC)


 * The other serious issue associated with link flap in RSTP is unicast flooding. RSTP requires forwarding tables be flushed on any RSTP-announced topology change. So with standard STP, it takes 30 seconds to respond to a failure. With RTSP your whole network gets flooded during some failure scenarios. Is SPB any better? ~Kvng (talk) 15:22, 2 December 2018 (UTC)

significance
Other than for STP, MAC addresses are just bit strings. There is no most or least significant bit. Since they are compared as a tie-breaker here, this article should explain how that is done. The is not so obvious, as Ethernet frames are sent byte by byte, with the least-significant bit of each byte first. Gah4 (talk) 20:07, 28 October 2022 (UTC)


 * A MAC address is a 48-bit field. Usually it is represented in number form where in any common notation, the most significant digit is leftmost and the least significant digit is rightmost. The entire number has the significance that is assigned to it on a certain point. For STP it is compared numerically, for identifying an L2 interface it is not. The byte and bit order that is used on Ethernet isn't relevant here, STPs are specified by IEEE 802.1. --Zac67 (talk) 21:38, 28 October 2022 (UTC)
 * There's what appears to be a compete explanation in Spanning Tree Protocol ~Kvng (talk) 14:35, 31 October 2022 (UTC)