Please see the attached file.
Data Communication Assignment 1 Q 1 The essential qualities of any system are correctness, reliability, robustness and security, compatibility and scalability, ease of use, and efficiency. Consider how these qualities relate to the Network Layer (Layer 3). For each of these qualities, describe if and how each of these qualities is provided by this layer. If the quality is not provided then explain why. Q1 answer should not exceed 3/4 pages. Q 2 An ISP has provided your company with the network 177.241.64.0/18. Devise a variable-length subnetting scheme that divides this into eighteen (18) usable subnets, that satisfy the following criteria: The smallest site has 369 users. The largest site has 1,000 users. There are 1,000,000 users in total. Your answer must include network addresses, broadcast addresses, netmask, and the maximum number of hosts supported per network, both before and after subnetting for each subnetting task. Any assumptions you make should also be included in your answer. Q2 answer should not exceed 3 pages. Q 3 Investigate the application protocol RFB and answer the following questions: a. [5 marks] Where RFB is used by an application, what functionality and services does RFB provide to the application? b. [2 marks] Which application architecture(s) does RFB protocol use? (ie. Client-server, peer-to-peer, thin-client, thick-client, etc.) c. [2 marks] Is data represented in RFB as text or binary (or something else)? d. [2 marks] How is this representation structured? (eg. Yaml, unstructured blob) e. [4 marks] Does RFB require any specific protocols be used in the lower layers of the protocol stack? f. [5 marks] What services or features provided by these specific lower layer protocols are necessary in order for RFB to function correctly? Your answers to Q3 will require supporting arguments and references that cite your research, since this is a networking unit you should use IEEE referencing style. Q3 answer should not exceed 4 pages. https://ieee-dataport.org/sites/default/files/analysis/27/IEEE%20Citation%20Guidelines.pdf https://ieee-dataport.org/sites/default/files/analysis/27/IEEE%20Citation%20Guidelines.pdf Comp6250 - Week 03 - Network Layer COMP6250 – Network Layer Internet Layer IP COMP6250 Data Communications 1 COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Outline TCP/IP Addressing Routing Subnetting Fixed length subnetting 2 Outline COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Important things to Understand ‣ What is IP and what does it do ‣ What is an IP address ◦ How is it structured ◦ How is the IP address used in routing ◦ IP address classes ‣ What routing is ‣ What forwarding is ‣ What routers are, what they do and why they only need to know about networks 3 Outline COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Network vs Internet Layers 4 Physical Data Link Internet Transport Application COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing TCP/IP’s 5-Layer Network Model 5 Intro COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing TCP/IP Protocol Family ‣ TCP/IP Network layer ◦ ARP, RARP, DHCP, BOOTP, IP, ICMP ‣ IP Routing (eg. RIP, OSPF) ‣ IP Multicasting: IGMP, DVMRP ‣ IP Error messages: ICMP ‣ Transport layer: TCP and UDP 6 Intro COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Internet Layer 7 Two major (and related) functions Routing Forwarding Intro COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Internet Layer ‣ Collects network topology into routing tables ◦ Routing protocols ‣ Packet handling ◦ Addresses (on source host) and forwards messages • Selects the best next hop from node to node until the message reaches destination ◦ Encapsulates on sending end • Adds network-layer header to message segments ◦ Forwards packets to next hop ◦ Decapsulates on receiving end • Removes the network-layer header at receiving end and passes encapsulated data up to the transport layer 8 Internet Layer Transport Layer Data Link Layer Intro COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing IP and Data-Link Layer 9 IP is concerned with whole journey Data-link concerned with each hop (link) Intro Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing COMP6250 - Network Layer Internet Protocol (RFC 791) 10 RFC – Huh? IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Network Devices 11 Network Device Host Router Host – an end system Router – an intermediate system Sends or receives messages Passes messages to another network COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Internet Protocol (IP) (RFC 791) ‣ IP provides ◦ universal addressing • IP addresses and only IP addresses used everywhere ◦ routing of packets between hosts ‣ IP delivers ◦ packets from source host to destination host ◦ end-to-end, not link-to-link ‣ IP is an unreliable connectionless packet delivery service 12 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Unreliable ‣ Unreliable means ◦ Delivery is not guaranteed. ◦ Makes a best effort attempt to deliver a packet. ◦ Along the way a packet might be ◦ lost ◦ corrupted ◦ delayed – which can cause ◦ out of sequence delivery ◦ duplication ◦ Acknowledgment not required when data is received. ◦ Sender/receiver not informed when a packet is lost, etc ◦ Acknowledgment of packets is responsibility of higher layer transport protocol such as TCP. 13 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Unreliable – Why? 14 IP Service Unreliable Real time (video, audio) if packet lost, or corrupted – too late can tolerate drop out Trying to recover makes things worse. Reliable non-real time files must be delivered bit for bit TCP does this (next week) COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Connectionless 15 Packets are independent of each other Order is unimportant to IP Packets just transmitted on network COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Packet 16 COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing IP Datagrams ‣ IP packets are called datagrams. ◦ Basic units of Internet-layer transfer ◦ Encapsulate transport-layer data • from TCP and UDP ◦ Datagrams are forwarded through the network ‣ IP datagrams sent to data-link layer ◦ data-link layer encapsulates in data-link layer frames ◦ data-link layer delivers to next hop 17 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Internet Protocol (IP) ‣ Two versions in current use ◦ IPv4: uses 32-bit addresses. ◦ IPv6: Mainly developed to increase IP address space due to the huge growth in Internet usage (128-bit addresses) ‣ Both versions have a variable-length payload field ◦ Max size depends on the data-link layer protocol. ◦ Ethernet’s max message size is 1,492 bytes • thus max size of TCP message: 1492 – 24 – 24 = 1444 bytes TCP header IPv4 header 18 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing IP Packet Formats IPv4 Header: 192 bits (24 bytes) IPv6 Header: 320 bits (40 bytes) 19 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Network Layer Functions ‣ Addressing (static) ◦ Internet Addresses ◦ Assignment of addresses ◦ Translation between network-layer addresses and other addresses (address resolution) ‣ Routing (static and dynamic) ◦ Routing protocols ◦ Information gathering about network topology ‣Forwarding (dynamic) ◦ Process of deciding what path a packet must take to reach destination 20 IP COMP6250 - Network Layer Outline Intro IP IP Addresses Subnetting Routing Address Allocation Address Resolution More Addressing Types of Addresses Try “ping”ing a URL; translation (corresponding IP address) will be given by the answer. These addresses must be translated from one type to another (for a message to travel from sender to receiver). This translation process is called address resolution. 21 Layer Address Type Example Address Analogy Application URL www.mq.edu.au Name Internet IP Address 137.111.13.34 Postal Address Data Link MAC Address 00:0C:00:F5:03:5A GPS Coordinate Note: with a postal address you can work out a route