Networking Explained - Math Problem Example

Networking Name: Course: Tutor: Date: Question 1: wireshark a) The following is the screenshot obtained after running the wireshark analysis for the University of Delhi. b) There were over 100 packet pairs that were captured. The main reason for this very big figure is due to the fact that the network was not silent. As the web page was in the process of downloading, there were other additional protocols running in the computer thus making the protocols so many. c) Ethernet II: 0000 00 08 74 d6 ef 7d 00 26 5a ce 54 bf 08 00 45 00 ..t..}.& Z.T…E. Internet protocol 0010 02 07 92 a4 40 00 33 06 82 50 48 33 27 dc c0 a8 ….@.3. .PH3’… Transmission control protocol 0020 00 50 12 55 60 ee 50 5f 3d 37 d8 85 50 19 …P.U’ P_=7..P. d) Source and destination addresses Ethernet II: Source: D-Link|_ce:54:bf (00:26:5a:54:bf) Destination: dellcomp_d6:ef:7d 00:08:74:d6:ef:7d Internet protocol: Source: 192.168.0.5 Destination: 202.141.141.34 Transmission control protocol: Source: mediavault-gui (3673) Destination: http (80) The source address is the address of the machine which is sending a request to get the webpage and the destination is the server which has the information stored in it. The information is used to link the two machines on the web. e) Sample frame 24 4.115030 192.168.0.5 202.141.141.34 HTTP GET /index.php?id=4 HTTP/1.1 Information: Frame 24: 739 bytes on wire (5912 bits), 739 bytes captured (5912 bits) The frame has three segments and the total size is: 5912+5912+739+739=13302 bits Question 2: Request for IP John PC (1) If IP address is not found the Request is broadcast to other servers. IP add to John PC (2) DNS Servers until its found IP add to John PC (3) Internet (4) Email goes to John’s pc (5) STEPS After writing the message and clicking send packets contain the recipient information. This information is sent to the nearest DNS server to resolve the IP add to recipient PC. In that server, it’s returned for sending. If not, The request is broadcast till found. When found it is returned to the sender which contacts the nearest gateway to send the packets. The gateway searches for the servers where John pc is and passes the packets to the gateway on the other side which then sends the info to John PC. The feedback is exactly the same. Steps as per the diagram 1) The sender requests for the IP address of the recipient to be resolved and sent to it 2) The IP address is searched for in the nearest DNS server and sent back for the information to be sent 3) The IP is added to the email as a header so that the recipient can be identified in the network and the information sent to the next server 4) The gateway sends the information to the internet and using the header the receiving machine is searched for 5) On identification, the recipient’s nearest gateway is fed the information which it uses to locate the receiving server and stores the information until John retrieves it. Question 3: Address resolution What is address resolution? This is the method which is used in determining the real address of a machine which is needed in order to perform a particular operation on the internet. In this case, the address of a particular workstation which is in a network can be translated into one which the internet can be able to handle. When the computer is involved in the execution of certain instructions, it first resolves the IP address through a series of algorithm the gets the Ethernet address so that the particular computer can be located on the web. How does TCP/IP perform network layer address resolution in the network layer? To send messages to a PC in its network, a PC must be on familiar terms with the exact data link layer’s address. In such a case, the TCP/IP software conveys a broadcast message in the direction of all other computers in its local subnet. A broadcast message is received and developed by all PCs in the identical LAN. The message is a specifically formatted TCP level request which uses Address-Resolution-Protocol (ARP) that declares “Whoever is IP address “xxx.xxx.xxx.xxx”, please send to me the data link layer address belonging to you.” The TCP software in that PC with that IP address then acts in response with its address for data link layer. The sender then transmits its messages using that address. The dispatcher also stores that data link layer address in the address table for prospective purposes. How does TCP/IP perform network layer address resolution in the data link layer? The term server-name-resolution is used to define the way in which the address at the application layer is translated into the address at the network layer. This can be exemplified by the act of translating a URL from www.mm.com to an IP address like 192.123.9.0. The process occurs through the help of a DNS service. The DNS services are provided by name servers which are widespread in the internet. They locate the IP addresses from a database which holds the corresponding IP address against the URL. They provide a kind of assistance same as directory assistance. When computers require the IP addresses of other computers, they send requests to the name servers requesting for the information. When the TCP/IP requires translation of this address, it starts with sending a TCP packet to the name server closest to it. This packet tells the DNS server to propel the requesting machine the IP address that is matching the Internet address that was provided. If the DNS has the identical name in the database, it sends in reverse a unique TCP packet with the accurate IP address. If the DNS server doesn’t have the Internet address in its catalog, it will subject the equivalent request to a further DNS server somewhere else on the Internet. Once your workstation receives the IP address, the address is stored in a particular server address board. This way, if you still need to contact the same PC again, your PC does not need to get in touch with any DNS server. Most server address-tables are more often than not deleted whenever you exit your computer. Question 4: a) difference between amplifier and repeater An amplifier does not have the ability to distinguish between an intended signals against noise; it amplifies uniformly everything which is fed into it. A repeater on the other hand does not enlarge the signal; it restores the signal. When it obtains a weak or corrupt signal, it generates a duplicate, bit by bit, at the former and original strength. A repeater can not be able to filter (Pontain, 2001). Compare and contrast stop‐and‐wait ARQ and continuous ARQ. c) Stop and wait ARQ vs continuous ARQ Stop-and-wait ARQ. With stop and wait ARQ, the transmitter sends a solitary code-word and then waits for a helpful acknowledgement (ACK) or unhelpful acknowledgement (NAK) prior to sending any additional code-words. The advantage of this ARQ is that it only calls for a half-duplex channel. The main drawback is that it squanders time waiting for the ACKs, ensuing a low throughput. Continuous ARQ. Continuous ARQ requires a full-duplex channel since code-words are sent endlessly until when a NAK is established. A NAK is then handled in either one of the two ways: With go back-N ARQ, the particular transmitter resends the faulty code-word plus all other code-words that had followed until NAK was established. N parameter is for the delay in the round trip. For geosynchronous-satellite-channels, N can be very huge as of the 540 Millisecond round-trip-delays. d) What is transmission efficiency? Transmission efficiency in a network means the way in which the sending computer enhances that all the bits that were intended for a particular destination get to it without packet losses on the way. This is enhanced using flow control or multiplexing. Ethernet frame layout The format has a starting delimiter which is 1 byte, a destination address (6 bytes), source address (6 bytes), length, (2 bytes), LLC header and field for information (46-1500 bytes) and a frame check sequence (4 bytes). The Frame Check Sequence which is abbreviated as FCS is a fraction of the entire frame which is put into place so as to confirm that the specific information contained in every frame does not get altered during the process of transmission. If a frame is besmirched during communication, the FCS will not be equivalent with the recipient's FCS. Any frames that do not equal the calculated FCS are discarded. Question 5: AARNet The Australian Academic and research network is concerned with offering the internet to education and research communities in Australia. It serves the Australian education system and also the research partners involved. It incorporates 37 universities and also the CSIRO Australia. AARNet is an IP network. It though supports multiple protocols apart from voice, SNA and fax. It does not support the ISO OSI standards like the X25. This is because of the chief concern on speed. It now works as a completely fledged ISP in affiliation with Corinthian engineering, Pegasus and connect.com. Network diagram Connection is through 10 gigabit/sec circuits which connect to Australia and also overseas. It has an on campus wireless connection and also a national service which uses dial up. It has a traffic control with a download quota of 750 mb which is free. In order to be able to access the internet one must have UQ login information (Pontain, 2001). Question 6: Telstra Telstra provides internet subscription and a variety of internet services. They include IP networking, network hosting, email, and servers through: - Telstra Internet Direct: - this provides internet subscription, services which include IP networking and email services to businesses, the government and enterprises. It is mainly concerned with businesses and does not supply to individuals. Telstra Big Pond: it provides internet subscription Cable, Wireless, ADSL, and Dialup for suburban customers and small businesses. Big Pond is Australia's major internet service provider as it has over 2,000,000 subscribers. . Telstra Wholesale resells or leases telecommunications to other corporations for the rationale of resale at a charge. The speed is about 30Mbits/sec and ADSL speed of 8 Mbit/s/384kbit/s in some areas. It will also be offering fiber to the node technology (FTTN) which will improve download speed to 100Mbits/s. Optus Optus internet services comprise of:- Dial-Up Internet (Residential) in All States Broadband Internet (Residential) (cable and DSL) in all states apart from Tasmania and also does not offer to the Northern Territory. Satellite Internet Commercial internet and Wholesale internet access Secure-Gateway services which is solely for Federal-Government departments Optus has also integrated a hybrid roll out of fibre coax. Optus net provides cable broadband and customer dial up. It also has ADSL and ADSL2+ services (pontain, 2001). Iinet internet services iinet has a market share of 12.4%. It provides ADSL and WAIX services. The company also has a structure which provides DSLM infrastructure known as iiSLAMs. iiNet Limited offers Broadband and IP telephony modes of communication to consumers and also to business customers. Its products are broadband2+ (ADSL2+) services and also have incorporated VOIP services for its businesses. iiNet is part of the Terria-consortium which is at present bidding to construct the National-Broadband-Network. The following are the broadband settings for iinet. Modulation: ADSL2+ (broadband2+), G.DMT (broadband1) Encapsulation: PPPoE Multiplexing: LLC Authentication: PAP Username: john.citizen@iinet.net.au VPI: 8 VCI: 35 Reference Pountain, D. (2001). Networking explained. New York: Penguin Books. Read More