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Differences between revisions 5 and 14 (spanning 9 versions)
Revision 5 as of 2005-04-01 03:39:55
Size: 1521
Editor: GuyHarris
Comment: Fix the link to the LLC page.
Revision 14 as of 2011-06-27 05:32:14
Size: 2429
Editor: WenchaoWang
Comment:
Deletions are marked like this. Additions are marked like this.
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XXX - add a brief STP description here
The '''Spanning Tree Protocol''' ('''STP''') is a network protocolthat ensures a loop-free topology for any bridged Ethernet local area network.
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XXX - add a brief description of STP history
STP is a Data Link Layer protocol. It is standardized as IEEE 802.1D. As the name suggests, it creates a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches), and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes.
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* ["LLC"]: Typically, STP uses [wiki:LLC 802.2 LLC] as its transport protocol, running on link-layer protocols in the LanProtocolFamily such as ["Ethernet"].
 * [[LLC]]: Typically, STP uses [[LLC|802.2 LLC]] as its transport protocol, running on link-layer protocols in the LanProtocolFamily such as [[Ethernet]].
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{{attachment:STP.JPG}}
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XXX - Add example traffic here (as plain text or Ethereal screenshot). == Wireshark ==
The STP dissector is fully functional and supports IEEE 802.1D BPDU, Rapid Spanning-Tree BPDUs, and MST/MSTI BPDUs. Also add info of additional Wireshark features where appropriate, like special statistics of this protocol.
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== Ethereal == Cisco has a custom TLV extension called Per Vlan Spanning Tree (PVST+). The extension is added to 802.1D and RST BPDUs sent on 802.1Q VLAN trunks. The extension at the end of the BPDU advertises the VLAN ID (PVID) that the BPDU was sent on. The extension has the following format. It should be noted that only 802.1D and not RST BPDUs include the one padding byte for alignment.
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The STP dissector is (fully functional, partially functional, not existing, ... whatever the current state is). Also add info of additional Ethereal features where appropriate, like special statistics of this protocol.  * Even byte padding (802.1D only): 1 byte
 * Type (only PVID type 0x00 is supported): 2 bytes
 * Length: 2 bytes
 * Data: PVID is 2 bytes
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XXX - Add a simple example capture file to the SampleCaptures page and link from here. Keep it short, it's also a good idea to gzip it to make it even smaller, as Ethereal can open gzipped files automatically.
* [[attachment:SampleCaptures/stp.pcap]]
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A complete list of STP display filter fields can be found in the [http://www.ethereal.com/docs/dfref/s/stp.html display filter reference] A complete list of STP display filter fields can be found in the [[http://www.wireshark.org/docs/dfref/s/stp.html|display filter reference]]
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 Show only the STP based traffic: {{{
 stp }}}
 . Show only the STP based traffic:
{{{
 stp
}}}
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Capture only the STP based traffic: {{{
 stp }}}
 . Capture only the STP based traffic:
{{{
 stp
}}}
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* IEEE 802.1D: [http://standards.ieee.org/getieee802/download/802.1D-2004.pdf IEEE standard for local and metropolitan area networks--Media access control (MAC) Bridges].
 * IEEE 802.1D: [[http://standards.ieee.org/getieee802/download/802.1D-2004.pdf|IEEE standard for local and metropolitan area networks--Media access control (MAC) Bridges]] (for STP and RSTP).
 * IEEE 802.1Q: [[http://standards.ieee.org/getieee802/download/802.1Q-2003.pdf|IEEE Standards for local and metropolitan area networks-—Virtual Bridged Local Area Networks]] (for MSTP).

Spanning Tree Protocol (STP)

The Spanning Tree Protocol (STP) is a network protocolthat ensures a loop-free topology for any bridged Ethernet local area network.

History

STP is a Data Link Layer protocol. It is standardized as IEEE 802.1D. As the name suggests, it creates a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches), and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes.

Protocol dependencies

Example traffic

STP.JPG

Wireshark

The STP dissector is fully functional and supports IEEE 802.1D BPDU, Rapid Spanning-Tree BPDUs, and MST/MSTI BPDUs. Also add info of additional Wireshark features where appropriate, like special statistics of this protocol.

Cisco has a custom TLV extension called Per Vlan Spanning Tree (PVST+). The extension is added to 802.1D and RST BPDUs sent on 802.1Q VLAN trunks. The extension at the end of the BPDU advertises the VLAN ID (PVID) that the BPDU was sent on. The extension has the following format. It should be noted that only 802.1D and not RST BPDUs include the one padding byte for alignment.

  • Even byte padding (802.1D only): 1 byte
  • Type (only PVID type 0x00 is supported): 2 bytes
  • Length: 2 bytes
  • Data: PVID is 2 bytes

Preference Settings

There are no STP specific preference settings.

Example capture file

* SampleCaptures/stp.pcap

Display Filter

A complete list of STP display filter fields can be found in the display filter reference

  • Show only the STP based traffic:
     stp

Capture Filter

  • Capture only the STP based traffic:
     stp

Discussion

STP (last edited 2011-06-27 05:32:14 by WenchaoWang)