Abid Afsar     TNS    Assignment II   Student Number: 2823134                          Assignment Cover SheetStudent name:...
Abid Afsar              TNS      Assignment II        Student Number: 2823134Date due:                      23/12/2011Date...
Abid Afsar          TNS     Assignment II   Student Number: 2823134  • International organization for standardization (ISO...
Abid Afsar      TNS    Assignment II   Student Number: 2823134   • ATM model corresponds to functionality physical and por...
Abid Afsar         TNS   Assignment II   Student Number: 2823134   • OSI lowest layers are related to ATM, and diagrammati...
Abid Afsar       TNS    Assignment II   Student Number: 2823134  Answer:   • In term of sending user information, ATM prot...
Abid Afsar       TNS    Assignment II   Student Number: 2823134Figure 3: End- to-End Communication an ATM network  (3) Des...
Abid Afsar          TNS   Assignment II   Student Number: 2823134     • In diagrammatic form it is represented as         ...
Abid Afsar             TNS   Assignment II   Student Number: 2823134       • Diagrammatically the concept of UNI and NNI i...
Abid Afsar           TNS      Assignment II   Student Number: 2823134             discarded or it show the status of conge...
Abid Afsar          TNS   Assignment II   Student Number: 2823134     • ATM address use virtual circuit and it is 20 bytes...
Abid Afsar        TNS    Assignment II   Student Number: 2823134         iii.   E.164         The     three   different   ...
Abid Afsar       TNS    Assignment II   Student Number: 2823134     • It further sub divide into two sub layers that is se...
Abid Afsar       TNS   Assignment II    Student Number: 2823134  (6) What are Partial Packet Discard (PPD) and Early Packe...
Abid Afsar       TNS   Assignment II   Student Number: 2823134  1. Network Recourse Management: This is always a priority ...
Abid Afsar       TNS   Assignment II   Student Number: 2823134  4. Priority Control: An ATM cell have the priority cell lo...
Abid Afsar         TNS     Assignment II       Student Number: 2823134  into logical networks and each logical network has...
Abid Afsar       TNS    Assignment II   Student Number: 2823134  5. It has small routing table  6. It is capable of scalab...
Abid Afsar               TNS      Assignment II            Student Number: 2823134             For example: we want to sen...
Abid Afsar               TNS    Assignment II        Student Number: 2823134             In contrast selective reject prot...
Abid Afsar      TNS    Assignment II   Student Number: 2823134Selective reject protocol improves the channel usage time an...
Abid Afsar         TNS   Assignment II   Student Number: 2823134[1]. Tanenbaum, Andrew S. Computer Networks. Upper SaddleR...
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Mscc Tns Assignment Ii Student Number 2823134 Abid Afsar

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Mscc Tns Assignment Ii Student Number 2823134 Abid Afsar

  1. 1. Abid Afsar TNS Assignment II Student Number: 2823134 Assignment Cover SheetStudent name: Abid AfsarStudent number: 2823134Faculty: Computing ScienceCourse: TNS Stage/year: 1Subject:Study Mode: Full time Yes Part-timeLecturer Name: Faheem BukhatwaAssignment Title: TNSNo. of pages: 20Disk included? Yes No NoAdditional (ie. number of pieces submitted, size of assignment, A2,Information: A3 etc) 1
  2. 2. Abid Afsar TNS Assignment II Student Number: 2823134Date due: 23/12/2011Date submitted: 23/12/2011Plagiarism disclaimer:I understand that plagiarism is a serious offence and have read and understoodthe college policy on plagiarism. I also understand that I may receive a mark ofzero if I have not identified and properly attributed sources which have been used,referred to, or have in any way influenced the preparation of this assignment, or if Ihave knowingly allowed others to plagiarise my work in this way.I hereby certify that this assignment is my own work, based on my personal studyand/or research, and that I have acknowledged all material and sources used in itspreparation. I also certify that the assignment has not previously been submittedfor assessment and that I have not copied in part or whole or otherwise plagiarisedthe work of anyone else, including other students.Signed: _______ ______________ Date:___23/12/2011___________________ Please note: Students MUST retain a hard / soft copy of ALL assignments as well as a receipt issued and signed by a member of Faculty as proof of submission. (1) Compare the ATM protocol’s architecture and associated layers, to those of the ISO-OSI reference model. Your answer or diagram should show the layers in each protocol stack. Answer: 2
  3. 3. Abid Afsar TNS Assignment II Student Number: 2823134 • International organization for standardization (ISO) also referred as Open system interconnection (OSI) reference model has the following seven layers, i. Application layer ii. Presentation layer iii. Session layer iv. Transport layer v. Network layer vi. Data link layer vii. Physical layer In comparison to OSI reference model, asynchronous transfer mode (ATM) has the following three layers i. ATM Adaptation layer ii. ATM layer iii. Physical layer • The OSI model is used for the transmission over unreliable medium, while ATM model works with reliable transmission medium, and it also accommodate a mechanism for error detection and correction. • In term of reliability ATM is currently the most reliable mode of transmission in comparison to OSI model. 3
  4. 4. Abid Afsar TNS Assignment II Student Number: 2823134 • ATM model corresponds to functionality physical and portion data layer of OSI model. • Diagrammatically the concept is represented as Figure 1: Comparison Diagram of ATM and OSI Architecture 4
  5. 5. Abid Afsar TNS Assignment II Student Number: 2823134 • OSI lowest layers are related to ATM, and diagrammatically it is represented as,Figure 2: Relation of OSI and ATM (2) Show with the help of a diagram the flow of cells in a real Communication from end to end, up and down the layers in the ATM Model. Show two intermediate switches in the diagram. 5
  6. 6. Abid Afsar TNS Assignment II Student Number: 2823134 Answer: • In term of sending user information, ATM protocol architecture is similar to TCP/IP protocol suit. ATM works same like TCP/IP to forward user information form one machine to another in the form of packets. • In regards to routing or switching and control is completely different because it fully connection- oriented which it establish in form of virtual connection • First a unique virtual connection is established which have their VCI number • Next communication begin and signalling standard agreement take place and then data transmission start from one user machine to another and exactly an original data order • Finally, on completion of transmission connection is terminated • ATM network mange data in specific order to manage the quality of services in a most sophisticated manner • On higher level it uses user plan and control plan for data • Diagrammatically the concept is visualised as, 6
  7. 7. Abid Afsar TNS Assignment II Student Number: 2823134Figure 3: End- to-End Communication an ATM network (3) Describe in details the ATM Cell structure. Answer: • An ATM use a fixed cell also called packet which is composed of 5 bytes of header and 48 bytes of payload. All data in ATM network is switched and multiplexed in the form of ATM cell. 7
  8. 8. Abid Afsar TNS Assignment II Student Number: 2823134 • In diagrammatic form it is represented as ATM Cell Figure 4: ATM Cell • ATM cell header can have the following two header format that is UNI (User to Network Interface) and NNI (Network- to-Network Interface). The UNI is interface is between network device and end user while NNI is between network to network device or between the two back bone networks 8
  9. 9. Abid Afsar TNS Assignment II Student Number: 2823134 • Diagrammatically the concept of UNI and NNI is illustrated as, Figure 5: UNI and NNI interface format • The above diagram can be explained as, in ATM cell header fields the first one is GFC( generic flow control) it provides local function, the second one is VPI(virtual path identifier) it is a unique identification number for every virtual path, third one is VCI (virtual channel number) it is a unique identification number of every virtual circuit, fourth one is Payload type identify that weather it contain user data or control data, fifth one is CLP(congestion lost priority) it identify that if a cell shows congestion it should be 9
  10. 10. Abid Afsar TNS Assignment II Student Number: 2823134 discarded or it show the status of congestion in the network and sixth one is HEC(header error control) it provided information in relation to any error encountered • Multiplexing is also in important feature of ATM cell, it multiplex different forms of data such voice, video and text. Multiplexing improve overall efficiency and also improve the performance of overall resources, diagrammatically it is illustrated as Figure 6: ATM Cell Multiplexing (4) Describe the address fields used for ATM addressing. Use a diagram to show the fields. Answer: 10
  11. 11. Abid Afsar TNS Assignment II Student Number: 2823134 • ATM address use virtual circuit and it is 20 bytes in length and the ATM has three distinct formats, in general term it is represented as Figure 7: ATM address Format • The parts of an ATM address can be defined as, the first part is the ATM switch identifier it composed of 13 bytes, and identifies the switch position in network. The main three addressing scheme viewing location of switch differently. The second one is adapter MAC address hold 6 bytes. It shows the particular adapter type in the ATM network and the MAC address operation is similar like in Ethernet or token ring. The third one is selector (SE) hold a space of 1 byte, and it chooses a logical connection end point on physical ATM adapter. • The three addressing schemes use in ATM networks are i. Data Country/region Code (DCC) ii. International Code Designator (ICD) 11
  12. 12. Abid Afsar TNS Assignment II Student Number: 2823134 iii. E.164 The three different format of ATM address is diagrammatically illustrated as Figure 9: ATM Distinct Address Format (5) Describe the structure of the ATM Adaptation layer AAL5 and the services provided by each. Answer: • The AAL layer provide interface to the upper layer of the ATM reference model 12
  13. 13. Abid Afsar TNS Assignment II Student Number: 2823134 • It further sub divide into two sub layers that is segmentation and reassembling, and convergence • The basic duty of ALL layer is the format conversion • The ALL received 48 bytes payload from higher level layer and a header of 5 bytes from ATM layer • ALL have four different types that are AAL 1, ALL 2/3, ALL 4 and AAL 5. • These different types of ALL’s can also be distinguished by connection oriented or connectionless mechanism. The ALL 1, 2,5 are pulley connection oriented while ALL ¾ is partly connection oriented and AAL ¾ is partly connectionless as well. • Diagrammatically it is represented as 13
  14. 14. Abid Afsar TNS Assignment II Student Number: 2823134 (6) What are Partial Packet Discard (PPD) and Early Packet Discard (EPD)? Answer: these are the ATM cell discard techniques and segments large size packets into a series of bursts at ATM and ALL 5 cells. This phenomenon is very useful at ATM over IP (AIP) and ATM over LAN emulation (LANE) networks. These techniques closely work with traffic policy and also look on to QoS as well. When the cells of a large packet are dropped due to some reason and some of the fragmented packets are also discard and will be send for transmission. The discarding or dropping of fragmented packets are call partial packet discard (PED). And when cells are fragmented portion of a large packet, and are known in advance that the buffer space is not sufficient to accommodate the entire packet, and then there is no need to send some of its cells. It is better to discard the entire packet and will be retransmitted this whole phenomena is called early packet discard (EPD) (7) Discuss in details four traffic control mechanisms used in the ATM Model. Answer: the ATM network should always be capable to recover from any sort of potential errors, weather a human or machine error such as intermittent or accidental and so on. The following control mechanism are widely used in ATM traffic management arena 14
  15. 15. Abid Afsar TNS Assignment II Student Number: 2823134 1. Network Recourse Management: This is always a priority of network management to achieve good quality and efficiency, and meet the user quality of service requirements. There is no perfect standard for network resource is available until today. The core problem is the statistical behaviour of the ATM networks because several cells were entered into the buffer from different sources and also due multiplexing as well. 2. Connection Admission Control: it is the initial call setup procedure, and to establish a virtual channel or path that is acceptable to the network. It will make sure that the new connection will not devalue the other connection already in place and the quality of other channel is not affected. 3. Usage Parameter Control and Network parameter Control (UPC/NPC): These two techniques doing different function at network interface. The UPC is functioning on user network interface while NPC functioning on network node interface. the main purpose of UPC and NPC is to secure the network resources from intentional and malicious attack. It will also check the validity of VPI/VCI entries, monitor traffic volume for the agreed traffic parameter and standards and guarantee that all traffic obeying the specified criteria, and check the accepted traffic volume on each access link. 15
  16. 16. Abid Afsar TNS Assignment II Student Number: 2823134 4. Priority Control: An ATM cell have the priority cell loss bit in the header. And the information is classed according to their priority and at least an ATM cell has two distinguished classes. 5. Traffic Shaping: It is a form of alerts given at the time when there is a speedy traffic on an access link, these alerts are given to slow their peak cell rate, limit the cell delay by appropriately organising the cells in time. 6. Congestion Control: is a state of a network in which the traffic overload or overflow on the network, everything jammed , and no new network connection can be established, the unguaranteed quality of service network is not able to add or remove network connection. These problem can be solved by using the above mechanism such as connection admission, and UPC and NPC. (8) Explain in detail how IP over ATM takes place. Your explanation must discuss: connecting IP to an ATM, addresses and the transfer of IP data grams. Answer: ATM network is connection oriented network and it widely support network protocols such as IP, Framerelay, and IPv6, IPX, Decnet and so on. An ATM use three types of connection which are permanent virtual circuit (PVC) and Soft PVC, and short virtual circuit (SVC). The ATM network is divided 16
  17. 17. Abid Afsar TNS Assignment II Student Number: 2823134 into logical networks and each logical network has own separate IP subnet also called logical subnet (LIS). Every system in the LIS has share the same IP prefix and net mask. In LIS end system communicant with each other through ATM end-to-end connection. And in a different LIS’s the communication is take place through router. (9) Describe the link state routing algorithm and list its advantages over distance vector routing algorithm. Answer: Link state is a routing protocol such as OSPF and IS-IS used in packet switch networking in computer communication. The main concept of the link state routing protocol is that every network node has to take routing information of the connected neighbours in the form of a table. Every network node calculates best to the other concerned destination. The calculated best path is then place in routing table. Advantages: 1. Link state algorithm converge fast than distance vector protocol 2. It use multicast to share the network information 3. It support classless routing 4. Link state operate better at large enterprise network 17
  18. 18. Abid Afsar TNS Assignment II Student Number: 2823134 5. It has small routing table 6. It is capable of scalability 7. It has a low network overhead 8. It has no node limits 9. It use cost for shortest path findings (10) Compare memory requirement imposed on the receiver node by selective reject protocol and the go-back-N protocol. Give examples to support your answers. Answer:Go-Back-N protocol manage the transmission time involved atreceiver end, and the transmission time of acknowledgment to comeback at sender end, and are carefully checked for efficiency purposeand the technique is called pipelining. The sender is obliged to keeptrack of frames and their concerned acknowledgment, and also haveto look timeout interval as well. As a result of tracking of each recordthe memory requirement for sender is increased. On the other handthe receiver only receives the frame or acknowledgment which thereceiver need. In situation where frame lost or duplication occurs inframes or acknowledgments, the receiver discards whole frame, andcall for resend. In memory perspective the receiver only needmemory, when the frame is in right order with no error, lost andduplication. 18
  19. 19. Abid Afsar TNS Assignment II Student Number: 2823134 For example: we want to send frames of window size 9, can be shown in the following figureSender End 0 1 2 3 4 5 6 7 8 Ack 0 Ack 1Receiver End 0 1 2 3 4 5 6 7 8 discard discard discard discard discard discard Error Retransmission of the same framesSender End 2 3 4 5 6 7 8 Ack 2 Ack 3 Ack 4 Ack 5 Ack 6Receiver End 2 3 4 5 6 7 8 In the above figure error occur in frame 2 and all the subsequent frames were also discarded. The sender was not aware of the problem, and again sends the same copies of the frame because of the timeout interval expiry. The limitation of go-back-n protocol is the sender unawareness of the problem, and this makes it inefficient. And negatively affect the channel usage, memory at sender side, and bandwidth. 19
  20. 20. Abid Afsar TNS Assignment II Student Number: 2823134 In contrast selective reject protocol when the problem occur during delivery of the frames, only particular frames were send back again by the sender. On the receiver end all frames are not discarded and only damage frame is acknowledged. In selective reject protocol receiver side buffer size is increased because of keeping every correct frame send by the sender. In this technique both sender and receiver vigilantly watch their time counter, and the receiver have knowledge that which frame has a problem and need to be re-acknowledge. It uses NAK (negative acknowledgment) for lost or damaged bit retransmission. For example: we want to send frames of window size 9, using selective reject protocol is shown in the following figureSender End 0 1 2 3 4 5 6 7 8 Ack 0 Ack 1 NAk 2 Ack 1 Ack 2 Ack 3 Ack 4Receiver End 0 1 2 3 4 5 6 7 8 buffered buffered buffered buffered buffere buffered Error d 20
  21. 21. Abid Afsar TNS Assignment II Student Number: 2823134Selective reject protocol improves the channel usage time andbandwidth, and also has a positive effect on the overall efficiency oftransmission between sender and receiver. Bibliography 21
  22. 22. Abid Afsar TNS Assignment II Student Number: 2823134[1]. Tanenbaum, Andrew S. Computer Networks. Upper SaddleRiver, NJ: Prentice Hall PTR, 1996. Print.[2]. Händel, Rainer, Manfred N. Huber, Stefan Schröder, and RainerHändel. ATM Networks: Concepts, Protocols, Applications.Wokingham, England: Addison-Wesley Pub., 1994. Print.v[3]. ATM Addresses." Microsoft TechNet: Resources for ITProfessionals. Web: 23 Dec. 2011<http://technet.microsoft.com/en-us/library/cc976977.aspx>.[4]. Clark, Martin P. ATM Networks: Principles and Use. Chichester,England: Wiley/Teubner, 1996. Print. 22

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