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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. Spanning tree is based on an algorithm invented by Radia Perlman. Image File history File links Please see the file description page for further information. ...
The Rapid Spanning Tree network protocol and algorithm provides a loop free topology for any LAN or bridged network. ...
Image File history File links Please see the file description page for further information. ...
The Multiple Spanning Tree network protocol and algorithm provides a loop free topology for any LAN or bridged network. ...
In networking, a communications protocol or network protocol is the specification of a set of rules for a particular type of communication. ...
A network topology is the pattern of links connecting pairs of nodes of a network. ...
Bridging is a forwarding technique used in packet-switched computer networks. ...
A local area network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a college. ...
The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...
Standardization, in the context related to technologies and industries, is the process of establishing a technical standard among competing entities in a market, where this will bring benefits without hurting competition. ...
Links ANSI/IEEE Std 802. ...
Flowcharts are often used to represent algorithms. ...
Radia Perlman is a software designer and network engineer sometimes referred to as the Mother of the Internet. She is most famous for her invention of the spanning-tree protocol which is fundamental to the operation of network bridges. ...
Spanning Tree Protocol operation
STP is used in switched networks to prevent loops, and has been standardised by IEEE 802.1d. Its structure corresponds to that of the spanning tree in graph theory. Networks must have only one path to any destination active at any one point in time, this is called a loop free topology. If more than one open path were to exist then data frames could loop endlessly (known as a broadcast storm) crippling the network. However, a good network design should include spare (redundant) links to provide an alternate path if one fails. The minimum spanning tree algorithm ensures that only one path to a destination is available at any one time by detecting loops and blocking switch ports as required. A modular network switch with 3 network modules (a total of 24 Ethernet and 14 Fast Ethernet ports) and one power supply. ...
Not to be confused with the Institution of Electrical Engineers (IEE). ...
A spanning tree (red) of a graph (black), superimposed In the mathematical field of graph theory, a spanning tree of a connected, undirected graph is a tree which includes every vertex of that graph. ...
A graph diagram of a graph with 6 vertices and 7 edges. ...
A network topology is the pattern of links connecting pairs of nodes of a network. ...
A broadcast storm is a networking situation in which messages are broadcast on a network, and each message prompts a receiving node to respond by broadcasting its own messages on the network that in turn prompt further responses, and so on. ...
The minimum spanning tree of a planar graph. ...
Electing a root bridge A loop free topology looks like a tree and at the base of every tree is its root. In a switched network a root bridge (switch) is automatically selected by the spanning tree algorithm. Each switch has a MAC address and a configurable priority number, both of these numbers make up the bridge identification or BID. The BID is used to elect a root bridge based upon the lowest priority number, if this is a tie then the lowest MAC address wins, and because no two MAC addresses are the same one switch will always be successfully elected as the root bridge. Other switches in the network will then calculate the shortest distance to the root bridge using bandwidth as a measurement and so produce a loop free tree topology. The priority number is normally left at its default value but can be reconfigured to a lower number if the network administrator wishes a particular switch to be elected; otherwise the whole process is totally automated. In computer networking a Media Access Control address (MAC address) is a unique identifier attached to most forms of networking equipment. ...
A network topology is the pattern of links connecting pairs of nodes of a network. ...
Bridge Protocol Data Units (BPDUs) BIDs and other Spanning Tree Protocol information are carried in special data frames called bridge protocol data units (BPDUs). BPDUs are exchanged regularly (every 2 seconds) and enable switches to keep track of network changes and activate or disable ports as required. When a device is first attached to a switch port it will not immediately start to forward data. It will instead go through a number of states while it processes BPDUs and determines the topology of the network. When a host is attached such as a computer, printer or server the port will always go into forwarding mode, albeit after a delay of about 50 seconds while it goes through the listening and learning states (see below). However, if another switch is connected the port may remain in blocking mode if it is determined that it would cause a loop in the network. In computing, a server is a software application that carries out some task (i. ...
A modular network switch with 3 network modules (a total of 24 Ethernet and 14 Fast Ethernet ports) and one power supply. ...
STP switch port modes:
- Listening - The switch processes BPDUs and determines the network topology
- Learning - The switch builds a switching table that maps MAC addresses to port numbers
- Forwarding - A port receiving and sending data, normal operation
- Blocking - A port that would cause a loop, no data is sent or received but it may go into forwarding mode if another link were to fail
- Disabled - Not strictly part of STP, a network administrator can manually disable a port
To prevent the delay when connecting hosts to a switch Rapid STP was developed and standardised by IEEE 802.1w which allows a switch port to go immediately into forwarding mode when an end device is attached.
Evolutions and extensions
Per-VLAN Spanning Tree (PVST) In Ethernet switched environments where multiple Virtual LANs exist, spanning tree can be deployed per Virtual LAN. Cisco's name for this is per VLAN spanning tree (PVST and PVST+ which is the default protocol used by Cisco switches). It has been suggested that IEEE 802. ...
A modular network switch with 3 network modules (a total of 24 Ethernet and 14 Fast Ethernet ports) and one power supply. ...
A virtual LAN, commonly known as a vLAN or as a VLAN, is a logically-independent network. ...
Cisco Systems, Inc. ...
Rapid Spanning Tree Protocol (RSTP) In 1998, the IEEE introduced an evolution of the Spanning Tree Protocol: Rapid Spanning Tree Protocol (RSTP) or 802.1w. In the 2004 edition of 802.1D, STP is superseded by the RSTP. The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...
The Rapid Spanning Tree network protocol and algorithm provides a loop free topology for any LAN or bridged network. ...
2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...
In printmaking, an edition is a set of prints off one plate, composing a limited run of prints. ...
Multiple Spanning Tree Protocol (MSTP) The 2003 revision of the standard also rolled in the Multiple Spanning Tree Protocol (MSTP) originally defined in IEEE 802.1s and later merged into IEEE 802.1Q-2003 The Multiple Spanning Tree network protocol and algorithm provides a loop free topology for any LAN or bridged network. ...
IEEE 802. ...
IEEE 802. ...
Trivia Radia Perlman, the inventor of the algorithm summarized it in the form of a poem, titled "Algorhyme":
(It should be noted that this poem was modified from the original entitled "Trees" by: Joyce Kilmer. Poetry (ancient Greek: poieo = create) is an art form in which human language is used for its aesthetic qualities in addition to, or instead of, its notional and semantic content. ...
Trees has more than one meaning: Trees, a poem by Joyce Kilmer for further disambiguation, see Tree_(disambiguation) slang for cannabis TreePeople, an environmental nonprofit based in Los Angeles This is a disambiguation page, a list of pages that otherwise might share the same title. ...
Joyce Kilmer (full name: Alfred Joyce Kilmer, December 6, 1886 – July 30, 1918) was an American journalist and poet; his best-known work is Trees. The poem is notable for its anthropomorphism: the tree in the poem presses its mouth to the earths breast and looks at God and...
- 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.
A labeled tree with 6 vertices and 5 edges In graph theory, a tree is a graph in which any two vertices are connected by exactly one path. ...
A packet is the fundamental unit of information carriage in all modern computer networks that use packet switching. ...
A local area network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a college. ...
The term may have one of the following meanings. ...
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