Token Ring

Token Ring

·         Network Topologies were discussed (Type of networks topology 2007) Token Ring operates as a logical ring but the devices are all connected to a hub-like device called a Multi-Station Access Unit (MSAU) which makes its physical topology a star. Sheesley (2008) stated that Token Ring was developed in the early 1980's by IBM as a way to connect PCs together. It was a direct competitor to the Ethernet standard that we use today and the ARCnet standard that disappeared in the mid-80's.

·         In token ring, Data being transmitted sequentially from one ring station to the next with a control token circulating around the ring controlling access. Token passing mechanism is shared by ARCNET, token bus, and FDDI, and has theoretical advantages over the stochastic CSMA/CD of Ethernet. A token ring network is wired as a star, with hubs and arms out to each station and the loop going out-and- back through each. Cabling is generally "Type-1" shielded twisted pair, with unique hermaphroditic connectors, commonly referred to as IBM data connectors in formal writing or colloquially as Boy George connectors Shah (2013: 22)

Other Logical Topologies:

Local Talk – it is a logical topology designed by Apple Computer, Inc. specifically for networking Macintosh computers. A case in which Local Talk may be appropriate is for a home network that requires simple configuration and does not require a high output. Local Talk uses a transmission method called Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA). It is similar to the CSMA/CD used in Ethernet networks, except that a node on a Local Talk network signals its intent to transmit before it actually does so. Through this, collisions and the need for the re-transmitting of data are usually avoided. (Y.Xin et al. 2003: 904).

 Token Ring Explained

Physical Topologies

PHYSICAL TOPOLOGIES

BUS TOPOLOGY AND RING TOPOLOGY

BUS TOPOLOGY

Dania in Tech (2015: 08) online says it is a network topology in which nodes are directly connected in common linear (or branched) half duplex link. Network cabling in which all computers and devices (nodes) are connected to a single cabling so that all nodes receive the message at the same time. Typically, the cable in the bus topology can have two terminals in there to dampen the signal so that it does not keep moving from one end to the other.

Linear or Distributed (types)

Linear implies that there is just one line associated with two distinct end points, whereas Distributed there may be more than one linear pattern connected to the network.

ADVANTAGES Dania (2015)  

·         Easy to implement and extend.

·         Well situated for temporary networks.

·         Initially less expensive than other topologies.

·         Cheap.

DISADVANTAGES Dania (2015)

·         Difficult to troubleshoot or administer.

·         Limited cable length and number of situations.

·         If there are problem with the cable, the entire network goes down.

·         Maintenance costs may be higher in the long run.

·         Performance degrades as add, frontal computers are added/ heavy traffic.

·         Low security (all computers on the bus can sell data transmissions).

·         One virus in the network will affect all of them (but not as much as ring or star network).

·         If one node fails, the whole network will shut down.

·         Proper termination id required.

·         If many computers are attached the amount of data flowing causes the network to flow down.

Bus topology: Jibesh Sitikhu

(2014) educatesansar.com/bus-topology-ethernet-protocol.html/

Ring Topology

RING TOPOLOGY

Dania in Tech (2015) think it is a network in which each node connects to exactly two other nodes, forming a single continuous pathways for signals through each node. Data travels from node to node, which each node along the way handling every packets. Ring can be unconditional with all traffic either clockwise or anticlockwise around the ring, or bidirectional (as in SONET/SDH). Unidirectional ring network can be disrupted by failure of a single link.  

ADVANTAGES Dania (2015)

·         Data is quickly transferred without a ‘bottle neck’ (very fast, all data traffic is in the same direction).

·         Transmission of data is relatively simple as packets travel in one direction only

·         Adding additional has very little impact on bandwidth

·         Prevents network collision because of media access method

DISADVANTAGES Dania (2015)

·         It is difficult to troubleshoot the ring

·         Total dependence upon the cable

·         Data packets must pass through every computer between sender and recipient therefore this takes it slower

·         If any of the nodes fail then the ring is broken and cannot be transmitted successfully

·         If order for all computers to communicate with each other, all computers must be turned out

·         Because all stations are wired together, to add a station you must shut down the network temporarily.

Ring topology: google.com/photos/xmattytv1/albums (2014) Matty-tv

Star Topology

STAR Topology

Vangie (2013) explains that with Star topology every node connects to a central hub, switch or computer; the hub acting as a server and the peripheral devices as clients.

Star Topology processes were discussed (Defining network topology 2011) the data on the star topology passes through the central device before reaching the intended destination. Hub acts as a junction to connect different nodes present in Star Network, and at the same time it manages and controls whole of the network. Depending on which central device is used, “hub” can act as repeater or signal booster. Central device can also communicate with other hubs of different network.

Disadvantages 

• Reliance on central device
• Higher costs
• Limited capacity for nodes by Penna Sparrow (2011)What you must know about a star topology is if the hub fails, all of the connected devices are disconnected.

Star topology: www.pbslearningmedia.org/resource (2015) Jeff Hampires

Star Topology explained

Mesh Topology

Mesh Topology

 Peter Ashwood (2011) states that  Mesh Topology is a network setup where each computer and network device is interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down.

The following is an illustration example of mesh network where each circle is representing a device connected to each other allowing transmission to take place:

Mesh topology: Shyseel Baral (2014) www.siteforinfotech.com/p/about-us

Vangie (2009) states that there are two types of mesh topologies: full mesh and partial mesh.

Mesh networking were discussed (Mesh advantage and disadvantage 2013) Mesh networking is expensive to have redundant connection to every computer, however you can make it cheaper by building a network that has some redundancy in the event one of the primary computers or connections in the network were to be down.

Hybrid Topology

Hybrid Topology

Hybrid Topology is an integration of two or more basic topologies to form a topology which has many advantages and a few disadvantages. This type of topology combination is done according to the requirements of a company/ organization.

For example if there is  a ring topology in one office department while a bus topology is in another department, connecting these two topologies results in Hybrid topology. Star-Bus Star-Ring are the most common types of hybrid Topology network. (Notes On Hybrid Topology: 2015)

Advantages

·         Reliable: Fault detection and troubleshooting.

·         Scalable: Easy to increase network size by adding new components, without existing architecture.

·         Flexible: Can be design according to requirements of the organization by optimising available resource. Special care can be given to node where traffic is high, and chance of faults is high.

·         Effective: Designed in such a way that strengths the constituent topologies are maximized while weakness are neutralized (D. Towsley et al: 2002)

Disadvantages

·         Complexity of design:  it is not easy to design this type of architecture configuration and installation process needs to be efficient.

·         Costly Hub: Hub used needs to be connected to two distinctive networks are very expensive.

·         Costly Infrastructure: larger in scale, require lots of cabling, cooling systems, and sophisticated network devices.  (T. Buetal : 2002) 

   Jajish Thomas (2015) www.ominsec.com

References

References

• Type of networks topology (Online).2007. Available: http://www.sqa.org.uk/e-learning/NetTechDC02CD/page_04.htm (Accessed 03 September 2015)
• Ethernet and Token ring (Online).2013 Available: http://www.slideshare.net/abhijeetshah55/ethernet-and-token-ring-16177627 (Accessed 03 September 2015)
• Does anyone actually still USE Token Ring? (Online).2008. Available: http://www.techrepublic.com/blog/classic-tech/?p=113 (Accessed 04 August 2015)
• Y.Xin, G.Rouskas and H. Perros. 2003. On the Physical and Logical Topology Design of
• Large-Scale Optical Networks. Journal of Lightwave Technology, 21(4): 904-905.
• Notes On Hybrid Topology (online).2015.Available: http://www.blossoms.mit.edu/ .
• (Accessed on 3 September 2015).
• T. Bu, N. Duf_eld, F. L. Presti, and D. Towsley. Network topologies. In Proc. ACM Sigmetrics, Marina Del Rey, CA, Jun. 2002.
• Roberts, Lawrence G.; Wessler, Barry D. (1970) Star Topology process (online). Available: http://www.telecomabc.com/ (Accessed on 05 September 2015)
• Mesh advantage and disadvantage 2013 (online). Available: http://www.ianswer4u.com/  (Accessed 0n 04 September 2015)
• Vangie, B. 2009 Types of mesh topology (online). 2009. Available: http:// http://www.webopedia.com/TERM/M/mesh.html (accessed on 07 September 2015).