Solving of Computer Networking - Math Problem Example

COMPUTER NETWORKING PROBLEM SOLVING REPORT 2 Student’s Name Class Instructor Institution of Affiliation City Date Q1. (a). Concept of polling and its effect on network congestion and saturation The switched Ethernet was developed to cub the problem of increased load in a network system that would often result to saturation in a classic Ethernet system. Polling is done on the switch to establish the required bandwidth for a real time system established within the protocol 802.16. In so doing, the capacity of the network is efficiently utilized. Whereas collisions are avoided in the use of a switch relative to the hub, without necessarily using the CDMA/CD algorithm, it is still significant to note that a single port within a switch may receive two frames at the same instance of time. Thus buffering is still a requisite tool of consideration. With many frames send to the buffer and with relative speeds of transmission, dropping the frames is bound to happen. Thus polling could still solve the potential event of discarding the frames when the limited buffer space is filled. It could be applied by allowing network subscribers being polled at set intervals to determine the required bandwidth and hence the switch device could sort the frames based on the bandwidth before porting them to the destination address. A hub also can be ported and polled to one of the destination for concentration of the frames and hence free the port buffers during a busy state. The advantage of polling the destination thus stands in that if a large bandwidth is required for transmission, the extra frames could be send to the concentration hub and hence queued and would avoid dropping. The main disadvantage would be a slight reduction in speed and also complex design for the switch to include the operation in its algorithm. (A Tanenbaum, 1944, 290) (b). Token bus data transmission on devices The token bus technology, though apparently has become deprecated employed the use of a token passing between devices that are connected to a network. The token bus is a logical topology that is best employed in a ring physical topology. Devices in the network would have a token circulating through the network with the destination address of the recipient device, and with the frames that need to be delivered. Each device in the network would receive the token, check the address and decide whether it matched or not. In case the token had the device address as its destination then it would read it and receive the frames, otherwise it would pass the token to the next device. The Token once it has delivered the attached frame would then be released and free to be picked by another device that has a send request. Thus in the token bus topology, the bus line is always active and there are no idle states upon the bus line. Thus in the token bus protocol, the sending device has control of the token which carries on frame a time, before being available again for any other device to use it.[Oli11] (c). Negative impacts of collision and broadcast on the throughput of an Ethernet. i. Using bus topology: In a bus topology, the backbone line of data transmission is only available when no device is transmitting. This ideally limits the use of the main resource to only two devices that have taken hold of the resource. Thus in the incident where the network address of recipient is multiple, delivery of the message won’t be instant since only two devices can communicate at a time. The overall speed of the network is greatly reduced and any other device cannot send data frames until the sender releases the bus after transmitting to all its recipient. Also, since the bus topology has only a single bus to be shared by all devices that have been connected to the network, a wrong address would mean that the bus won’t be released thereby blocking other devices from communication. As a result the network would be suspended indefinitely and thus lowering the overall throughput of the network. The idle time also when no device has data to send reduces the efficiency of the network rendering it cost ineffective.[Tan44] ii. Repeaters: These devices are important in boosting the transmission signal and avoid data loss due to the transmission medium. Since Ethernet network make use of twisted pairs of copper wires, which is a lossy medium, signal attenuation is bound to happen. Hence the power of the signal need to be boosted over a calculated span which stands to no more than 200 meters for cat 5 cables. Hubs: they are handy in network expansion, thus they allow more stations to be added to the Ethernet network without necessarily reconfiguring the layout and architecture of the network. However, since they have no processing power, they use fixed algorithm and mostly are not destination specific. They operate on broadcast mode for data packets.[Tan44] Bridges: Bridges are part of larger networks, creating a link between two or more local area networks that span over larger distances but for the same organization. They are useful in sharing same network resources and in establishing and running an intranet. They are good for large organizations to interlink in different parts of a locality such as a metropolitan. Switches: They operate much like hubs in network expansion and in adding or isolating a station from the network. However, they differ from hubs in that they are more intelligent and secure since they don’t broadcast messages to the entire node or devices connected to it, but rather, they determine the destination and pass the data frames uniquely to the destination without other ports having the knowledge of existence of the frames within the same router. This is achieved by having the router algorithms running on a powerful back-lane processing tools.[Oli11] Q2 (a) IPv4 checksum is a mistake discovery conspire that is utilized to shield IPv4 information bundles header from information defilement. Just the header of the datagram is checked utilizing this checksum. This is on account of, when communicating something specific, the sender computes the datagrams checksum and spots it on the header of the information parcel and after that sends the ascertained worth with the message. At the destination, the beneficiary computes the got information parcels header checksum again and cross checks to guarantee that the going with worth is indistinguishable. In the event that the numeric worth is not the same, then the information parcel has been adulterated. Cyclic repetition checks (CRC) are utilised at the connection layer with the end goal of identifying more sorts of bundle blunders. Notwithstanding being an advanced mistake checking component, CRC is not suitable for shielding information bundles from deliberate adjustment in light of the fact that CRC is a direct capacity and does not utilise verification in this way an assailant can control the message and recomputed the CRC making it difficult to distinguish the substitution. Furthermore, the CRC capacity is effectively reversible consequently it's unfit for use in advanced marks. However, on account of IPv4 checksum, any defilement of the information parcels is identifiable. (b) Subnet mask = 255.255.168.0 = 11111111 11111111 10101000 00000000 IP address = 165.131. 121. 110=10100101 100000011 1101110 01101111 10100101 10000011 1101110 01101111 (IP) 11111111 11111111 11000000 00000000 (mask) 10100101 10000011 1101110 00000000 165.131.64.0 (Network address) range= compliment of 11111111 11111111 1100000 00000000= 00000000 00000000 0011111 11111111 = 63.255 IP address range =165.131.64.0 to 165.131.127.255 (c) The switch portions the bundles into transmittable pieces with the most extreme part size been MTU (Maximum Transmission Unit) short the IP header size. The switch then puts each piece with its header checksum recomputed and section counterbalance field set into partitioned parcels and after that transmits them. At the destination, the recipients recognizes a bundle as a part if the banner for more pieces is set and the field for section counterbalance is nonzero. The collector utilizing neighborhood and remote web address, ID field and convention ID distinguishes the pieces and reassembles information from the parts having the same ID utilizing both more sections banner and part counterbalance. After accepting all pieces the collector figures unique information payload length, puts every one of the sections in the suitable request and passes the parts information for further preparing up the stack. [Tan44] IPv4 discontinuity adds to clog in that upon parcel fracture, the numerous sections prompts more bundle headers overhead, pieces reassembly at the accepting hub and extra steering choices. This makes a different assignments from one errand of transmitting stand out bundle to the destination which prompts clog. Furthermore, amid reassembly of parts, on the off chance that one piece is distinguished as missing the blunder checking system asks for the whole sections to be sent once more. This makes more activity and prompts clog. Likewise, in the event that the Internet portals get congested, they will likewise drop sections prompting missing pieces at the accepting hub consequently more retransmissions in this manner making more blockage. [Tan44] (d) (i) This convention joins ARQ blunder control and high-rate forward mistake revising coding. There is an expansion of repetitive bits to the information been transmitted happens where mistake identifying code, for this situation cyclic excess check is utilised. At the less than desirable end, the accepting hub after distinguishing a tainted datagram demands the sending hub to retransmit another datagram and the degenerate datagram is disposed of. (ii) Datagram ACK Datagram Datagram corrupt NAK Re-transmission (iii) The upsides of this convention include: It is a quicker method for transmission since as the degenerate datagram is disposed of and the getting hub anticipates a retransmission or the datagram is recognized, the sending hub can send other information and the accepting hub can get information in the same time interim. Endless supply of a degenerate datagram the getting hub sends a retransmission demand for the same datagram naturally until a blunder free datagram is retransmitted. The burdens of this convention is that all together for the datagram transmission to pass blunder recognition any given correspondence ought to be gotten without any mistakes. Also, an expanded number of parcel retransmissions brings down the information stream execution.[Oli11] Q3 (a) RIPv2 is generally utilised as a part of little systems while OSPFv2 is utilised by bigger systems. The data contained in RIPv2 upgrades incorporates routinely redesigned data from the switches depicting every switches steering database to every one of the switches it is associated with straightforwardly and an overhaul calculation The OSPFv2 redesign contains a topological database containing all associations in a neighbourhood system and a calculation that empowers the switches to overhaul their connection state frequently that clarifies every switches steering database to different switches[Oli11]. RIPv2 choices are said to originate from second-hand data since it monitors the switch that is nearest to every destination address while OSPFv2 choices are said to originate from direct data since it monitors every one of the associations topological database of a nearby system. (b) M 0 {C} 1 ∞ 0 ∞ 3 ∞ 1 {C,A} 2 ∞ 0 5 3 3 2 {C,A,F} 2 7 0 ∞ 3 3 3 {C,A,F,D} 1 7 0 5 3 3 Routing table Destination Next hop A 2 F 1 D 1 (c) (i) Header length (HLEN) is the web header length (32-bit words number). The IPv4 header length field determines the header measure that likewise relates with the information balance. The aggregate length field is a 16-bit field that decides the entire bundle size in bytes. In IPv6 payload length shows the IPv6 payload length and the field's size is 16 bits. Every one of these fields are connected in that the IPv6 is a variant of IPv4 header where once in a while utilized fields as a part of the IPv4 header were wiped out and fields giving better backing were added to better constant activity support.[Tan44] (ii) In IPv4 the convention field decides the conventions utilised as a part of the IP datagram information bit while the IPv6 next header field betokens either the upper layer PDU convention (TCP, UDP) or the augmentation header with no antecedent. The two are connected in that in the IPv6 sign of upper layer convention, comparable qualities utilised in IPv4 (while showing the upper layer convention) field are additionally utilised here. These conventions utilised as a part of IPv4 and IPv6 are the same and have not changed. (iii) In IPv4, Time-To-Live (TTL) field is 8 bits and helps keep datagrams from going in circles (holding on) on a web. It confines the lifetime of a datagram. In IPv6, the 8 bits bounce limit field be tokens the IPv6 bundles most extreme number of associations past which it can go before it is disposed of. The two fields are comparative aside from the absence of memorable connection to the time in which the bundle is lined at the switches line. References Oli11: , (Bonaventure, 2011, p. 140), Tan44: , (Tanenbaum, 1944, p. 364), Tan44: , (Tanenbaum, 1944, p. 427), Oli11: , (Bonaventure, 2011, p. 234), Tan44: , (Tanenbaum, 1944, p. 441), Tan44: , (Tanenbaum, 1944), Oli11: , (Bonaventure, 2011, p. 470), Oli11: , (Bonaventure, 2011, p. 55), Tan44: , (Tanenbaum, 1944, pp. 461,462), Read More