TCP/IP Model Quiz

Chapter 4-4 - Bluetooth, WiMAX, RFID, and Mobile Communications

• This chapter examines three wireless technologies: Bluetooth, WiMAX, and RFID.
• Bluetooth uses the 802.15 standard to connect computers, mobile phones, and devices.
• Data transmission occurs over the 2.4 GHz ISM frequency band, which is also used by 802.11b, g, n.
• Three output power classes exist for Bluetooth, with varying maximum output power and operating distances (see Table 11-5).
• When a Bluetooth device is enabled, it uses an inquiry procedure to discover available Bluetooth devices.
• The paging procedure synchronizes the connection between two Bluetooth devices, forming a piconet.
• A piconet is an ad-hoc network of up to eight devices, with one device acting as the master.
• WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless system designed for fixed and mobile broadband access.
• WiMAX operates in the 2 GHz to 66 GHz frequency range.
• Fixed station WiMAX access can cover up to 30 miles, while mobile access is 3-10 miles.
• WiMAX offers adaptable channel sizes (3.5 MHz, 5 MHz, 10 MHz), which ensures compatibility globally and optimizes data transfer rates.
• The WiMAX MAC layer differs from Wi-Fi, as WiMAX units only need one access attempt.
• WiMAX has a range of up to 31 miles and operates in both point-to-point and point-to-multipoint configurations.
• WiMAX is useful for last-mile connections, providing a cost-effective alternative.
• RFID (Radio Frequency Identification) uses radio waves to track and identify people, animals, objects, and shipments using the principle of modulated backscatter.
• The RFID system consists of RFID tags (transponders) with integrated antennas and radio electronics, and readers (transceivers) that transmit radio waves to activate tags.
• RFID systems have three parameters: powering the tag, frequency of operation, and communications protocol.
• RFID tags are classified as passive, semi-active, or active based on their power source.
• RFID operation frequencies include LF (125/134 kHz), HF (13.56 MHz), and UHF (860-960 MHz and 2.4 GHz).
• The Slotted Aloha protocol is used for RFID communications, reducing data collisions.
• Mobile communication technologies like CDMA (Code Division Multiple Access) and LTE (Long Term Evolution - 4G) are briefly introduced.
• 3G/4G and HSPA+ provide broadband wireless services.

Chapter 4-5 - Configuring a Point-to-Point Wireless LAN - A Case Study

• The chapter presents a proposal for a point-to-multipoint wireless network for a company.
• Company administrators want a wireless connection for employees back to the company's network.
• A site survey of the proposed antenna site on a hill 1 km from the home network is conducted.
• The site has a tower for mounting the antenna and clear views for 6 km in any direction.
• A wireless bridge connects the home network to the distribution point.
• Three antenna options (Omni, Yagi, Dish) are considered. Each has various costs and ranges.
• The administrators choose antenna A (omni-directional) for the site tower and this provides enough coverage for the 2 Mbps link needed for the remote users.
• An RF site survey verifies the signal quality of the selected antenna.
• Detailed measurements are taken from multiple locations within the planned coverage area.
• Remote user installations require a directional antenna (Yagi) plus a mount, lightning arrestor, and wireless bridge; this data link is for a 2 Mbps connection.
• The chosen antenna (Yagi) provides sufficient RF signal level for remote users.
• Each remote user needs a wireless bridge and switch to connect multiple users.

Chapter 4-6 - Troubleshooting Wireless Networks

• This section explains common techniques for troubleshooting wireless networks.

• Wireless networks, though easier to use, can sometimes fail.

• Checking hardware-related issues in wireless networks often involves the access point as the primary device.

• Pinging the access point's IP address helps verify network connectivity.

• Unplugging and replugging the access point resets it, in case of connectivity failures.

• Measuring signal strength ensures a "good" signal at the receiving location.

• Interference from electrical devices like microwave ovens (2.4 GHz) can affect signal strength.

• Maintaining a baseline measurement of signal strength helps in identifying issues.

• Wireless users share channels; large numbers of users can cause performance issues and packet drops due to heavy loads. Checking the access point's load capacity specifications may help.

• Access points usually assign 192.168.0.x IP addresses to clients.

• Using the command "ipconfig" verifies the assigned IP address.

• Resetting the SSID (Service Set Identifier) is valuable for connecting to or disconnecting your wireless device from a particular network.

• Most wireless systems support multiple security protocols (e.g., different versions of WPA/WEP).

• Ensuring the client and access point use the same security mode is crucial.

• Selecting a non-overlapping channel (e.g. channels 1 or 11) in Wi-Fi can reduce interference problems.

• Antenna placement (high up, unobstructed by metal) and avoiding physical obstructions improve signal range.

• Understanding that metal surfaces and thick materials can interfere with the signal range.

• Wireless client compatibility (hardware and software) and using the same wireless network standard is essential.

• Checking basic cable connections solves some unexpected problems

Chapter 6-2 - The TCP/IP Layers

• The TCP/IP model lists 4 layers: Application, Transport, Internet, and Network Interface.

• The Application layer defines the applications used to process requests, relevant ports and sockets.

• The Transport Layer defines connection types between hosts and acknowledgement methods.

• The Internet Layer defines protocols for addressing and routing data packets.

• The Network Interface Layer specifies how hosts connect to the network.

• The TCP/IP protocol was established before the OSI model, with the four layers correlating to the seven layers in the OSI model.

• TCP/IP supports application layer protocols like Telnet, FTP, SMTP, DNS, and SNMP for communication.

• Port numbers (Table 6-2) are reserved and assigned.

• Common application ports, like Telnet (23), FTP (20, 21), SMTP (25), DNS (53), DHCP (67, 68), TFTP (69), and HTTP(80) are included in Table 6-3.

• The transport layer is vital for establishing network connections, managing data transfer, and completing the connection.

• Two key transport protocols are TCP (connection-oriented) and UDP (connectionless).

• Establishing a TCP connection follows a three-way handshake (SYN, SYN+ACK, and ACK).

• TCP specifies the rules for establishing, managing, and terminating a connection; it handles error checking and data packet recovery.

• The UDP protocol is connectionless, which means data packets are sent without waiting for an acknowledgement; this is suitable for applications like streaming.

• The Internet layer defines protocols used for addressing and routing data packets through a network.

Chapter 6-4 - IPv4 Addressing

• IPv4 addresses use a 32-bit structure.

• IPv4 address classes (A, B, C, D, E) have specific numerical ranges and characteristics, influencing how they are used within a network to define network portions and host portions.

• Private IP addresses are allocated for internal networks (Intranets).

• ARIN is involved in assigning IP address blocks.

• Different address classes partition their 32-bit addresses differently (Table 6-8 & 6-9) showing how many bits are used for the network portion and how many bits are used for the host portion.

• Private IP addresses (Table 6-10) are not used for routing on the Internet.

• ARIN (the American Registry for Internet Numbers) is the organisation that assigns IP address space.

Chapter 6-5 - Subnet Masks

• Subnetting divides networks into smaller networks (subnets) using subnet masks.
• The subnet mask defines which bits of an IP address identify the network/subnet and host portion.
• Subnets are created by borrowing bits from the host portion of the IP address.
• The subnet mask defines the network/subnet bits, allowing routers to forward traffic to the appropriate subnet.
• Equations are used to calculate the total number of subnets created and the number of usable host addresses per subnet.
• A subnet has a network address and a broadcast address; these addresses are different from typical host addresses in the subnet.
• Subnet masks are used to distinguish whether traffic is directed to a host on the same local area network or routed to a gateway.