Guide to Networking Essentials, 6th Edition Chapter 2: Network Hardware Essentials

Objectives In this chapter, students will learn: Basic operation of network repeaters and hubs The purpose of network switches The operation of wireless access points the basic operation of network interface cards The function of routers Copyright © 2012 Cengage Learning. All rights reserved. 2

Intro; Repeaters; Hubs PP. 61-66 Section 1.1 Intro; Repeaters; Hubs PP. 61-66 Copyright © 2012 Cengage Learning. All rights reserved.

Network Repeaters and Hubs Early networks didn’t use interconnecting devices Severely limited network size Total cable length and number of computers Copyright © 2012 Cengage Learning. All rights reserved.

Network Repeaters and Hubs Repeats signal Used to extend networks A repeater receives bit signals generated by NICs and other devices, strengthens them, and then “repeats” them to other parts of the network Enables you to connect computers whose distance from one another would make communication impossible Two ports Copyright © 2012 Cengage Learning. All rights reserved.

Network Repeaters and Hubs A repeater extends the length of a network Copyright © 2012 Cengage Learning. All rights reserved.

Hub (Multiport Repeater) Hub – a multi-port repeater Signaling Process: Receives signal from one port Cleans the signal - Filters out electrical noise Regenerates the signal to full strength Transmits the signal to all other ports Copyright © 2012 Cengage Learning. All rights reserved.

Hubs (Multiport Repeaters) A multiport repeater or hub Copyright © 2012 Cengage Learning. All rights reserved.

Hubs and Network Bandwidth Network Bandwidth – The amount of data that can be transferred in an interval. Usually measured in bits per second (bps) Speeds range from 10 Mbps up to 10 Gbps Bandwidth sharing – when all computers connected to the hub must share the amount of bandwidth the hub provides Causes collisions Copyright © 2012 Cengage Learning. All rights reserved.

Hub Indicator Lights Power, link status, network activity, collisions Uplink port – port used to connect two hubs together or hub to a switch Simulation 3: Basic operation of a hub Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check Enables you to connect computers whose distance from one another would make communication impossible. Repeater Networking device that sends data out all ports Hub Two things that hubs do to improve data quality Cleans and regenerates signal going out all ports Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check Name the four lights found on a network hub Power, link status, network activity, collisions Network Bandwidth The amount of data that can be transferred in an interval How is network bandwidth measured? bps (Mbps or Gbps) Copyright © 2012 Cengage Learning. All rights reserved.

Section 1.2 Switches and WAPs PP. 66-79 Copyright © 2012 Cengage Learning. All rights reserved.

Network Switches Looks like a hub Inside a LAN Reads data a frame at a time Gets MAC address from each frame Forwards the message to only the port tied to that MAC address. Copyright © 2012 Cengage Learning. All rights reserved.

Network Switches Switches maintain a switching table Copyright © 2012 Cengage Learning. All rights reserved.

Network Switches Steps of switch operation: 1. Receives a frame. 2. Reads the source and destination MAC addresses. 3. Looks up the destination MAC address in its switching table. 4. Forwards the frame to the port where the computer owning the MAC address is found. 5. The switching table is updated with the source MAC address and port information. Simulation 4: Basic operation of a switch Copyright © 2012 Cengage Learning. All rights reserved.

Switches and Network Bandwidth Each port gets dedicated bandwidth Can operate in full-duplex mode Can send and receive data simultaneously Hubs only half-duplex Switches are the preferred device because of these advantages Copyright © 2012 Cengage Learning. All rights reserved.

Switch Indicator Lights Link status indicators Activity indicators May have full-duplex or half-duplex mode indicators Uplink Port – Used to connect switches Expand network Some switches have a dedicated uplink Copyright © 2012 Cengage Learning. All rights reserved.

Wireless Access Points Wireless Access Point - Operate similarly to a hub without wires. Wireless Router - combines the functions of an AP, a switch, and a router Small businesses and home networks Wireless LANs usually attached to wired networks Copyright © 2012 Cengage Learning. All rights reserved.

Wireless Access Points A wireless router Copyright © 2012 Cengage Learning. All rights reserved.

Basic AP Operation All stations hear all data being transmitted Receiving device sends an acknowledgment back to the sending device to indicate successful reception Request to send (RTS) - optional Workstation requesting permission to transmit to AP Clear to Send (CTS) - optional AP response saying it OK to transmit Copyright © 2012 Cengage Learning. All rights reserved.

Wireless APs and Network Bandwidth All the extra chatter required to send data in a wireless network slows communication The effective bandwidth is about half of effective bandwidth found on physical networks Most APs operate from 11Mbps to several hundred Mbps 11 Mbps is 802.11b which is outdated Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check Which networking appliance reads frames and sends each frame out only one port Switch How do switches (typically) know what port to send out a message. Switching table Can send and receive data simultaneously (term) Full-duplex Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check A special port used to connect switches Uplink Port A wireless device that is similar to a hub Wireless Access Point (WAP) Message sent to the AP when a workstation wants to transmit. Request to send (RTS) Message sent to workstation from AP indicating it is OK to send the message Clear to Send (CTS) Copyright © 2012 Cengage Learning. All rights reserved.

Lab 1.2 Setup a Basic Network: To put on same LAN: Try One computer per team Use a single switch to put them on the same LAN To put on same LAN: Use Windows search feature to access the “networking and sharing center” Select “Change adapter settings” in the upper left corner. right-click - “Local area connection” and select “properties” Enter password From the Networking tab select “Internet Protocol Version 4 (TCP/IPv4)” Press the “properties” button Set your own IP address by pressing the “use the follo Try IP Address - 192.168.0.1 Subnet Mask - 255.255.255.0 Copyright © 2012 Cengage Learning. All rights reserved.

Section 1.3 NICs PP. 79-88 Copyright © 2012 Cengage Learning. All rights reserved.

Network Interface Cards Connect computer to medium Incoming messages: Receives bit signals and assembles them into frames Outgoing messages: receive packets from network protocol Creates frames by adding MAC addresses and error check Converts frame into bit signals and transmits them Copyright © 2012 Cengage Learning. All rights reserved.

Network Interface Cards A NIC handles incoming data from the network medium Copyright © 2012 Cengage Learning. All rights reserved.

Network Interface Cards NIC required to attach to networking medium Networking medium might be copper wire, fiber-optic cable, or airwaves Most NICs are built into a computer’s motherboard May use more than one NIC (especially servers) It is important to know how to install a new NIC Copyright © 2012 Cengage Learning. All rights reserved.

Network Interface Cards A NIC handles outgoing data to be sent to the network medium Copyright © 2012 Cengage Learning. All rights reserved.

NICs and MAC addresses All NICs have a unique MAC address MAC address is stored in read-only memory (ROM) on the NIC MAC Address = Two 24-bit hexadecimal numbers 24-bit manufacturer ID called OUI 24-bit serial number assigned by the manufacturer 48-bit address expressed in 12 hexadecimal digits: 04-40-31-5B-1A-C4 Copyright © 2012 Cengage Learning. All rights reserved.

The NIC as a Gatekeeper NIC validates the MAC addresses of incoming frames Three ways a frame may be accepted by a NIC: Match the MAC address of the NIC Broadcast frame (ff-ff-ff-ff-ff-ff) If NIC is in permiscuous mode Unicast Frame – A frame addressed to only one computer on the LAN When the destination MAC address matches the NICs MAC address, it’s a unicast frame Copyright © 2012 Cengage Learning. All rights reserved.

The NIC as a Gatekeeper Broadcast Frame – A frame designed to be sent to all computers on a network. Typically: ff-ff-ff-ff-ff-ff Promiscuous mode – turns off the gatekeeper functions and enables the NIC to process all frames it sees Simulation 5: How a NIC works Copyright © 2012 Cengage Learning. All rights reserved.

NIC Indicator Lights NICs have indicator lights to show status information Usually a link status indicator and an activity indicator The link light is usually green when connected to a network Some NICs support multiple speeds Usually a separate light for each speed so that you can determine at what speed the NIC is connected to the hub or switch In other cases the light is a different color for each speed, such as amber for 100 Mbps and green for 1000 Mbps Copyright © 2012 Cengage Learning. All rights reserved.

Selecting a NIC NICs commonly built into motherboard An additional NIC or a faster NIC may need to be installed When selecting a NIC you need to select correct bus interface PCI-Express is most common The NIC driver (software) must be available for your OS For servers, consider a NIC with onboard memory and multiple ports that performs faster Copyright © 2012 Cengage Learning. All rights reserved.

NIC Drivers Most OSs ship with NIC drivers NICs ship with drivers for the most common OSs If the OS has a suitable driver available, it is installed automatically After installation, Windows 7 shows your installed NIC as a “Network Connection” In Windows, each connection is assigned a name as in “Local Area Connection”, “Local Area Connection 2” You can rename these Copyright © 2012 Cengage Learning. All rights reserved.

NIC Drivers Copyright © 2012 Cengage Learning. All rights reserved.

Wireless NICs NICS use SSID to join the network. Choose Wireless NICs based on the type of wireless AP Typical Wireless Standards: 802.11n; 802.11ac Older standards: 802.11a, 802.11b, and 802.11g Service Set ID (SSID) - the name assigned to the wireless network NICS use SSID to join the network. Typically need to enter a security key or UID and PSWD Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check What is required to attach a computer to a network Network Interface Card (NIC) What does the NIC do with bit signals coming from network? Assembles them into frames What identification code is tied to a NIC MAC address Three ways a frame may be accepted by a NIC: Match the MAC address of the NIC Broadcast frame (ff-ff-ff-ff-ff-ff) If NIC is in permiscuous mode Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check NIC setting that the gatekeeper functions and enables the NIC to process all frames it sees Promiscuous mode What color is the link light when successfully connected to a network Green Consider a NIC with onboard memory and multiple ports that performs faster if the computer is a Server The name assigned to the wireless network Service Set ID (SSID) Copyright © 2012 Cengage Learning. All rights reserved.

Lab 1.3 To Do Disable integrated NIC and add a new one to a junker Work with two of the servers in promiscuous mode Start using Wireshark now Evaluate “Packet tracer” Lookup networking symbols Should we just use Cisco standards? Are there other standards we could use? Copyright © 2012 Cengage Learning. All rights reserved.

Section 1.4 Routers PP. 88-100 Copyright © 2012 Cengage Learning. All rights reserved.

Routers Most complex networking device Connect LANs together to create an internetwork Copyright © 2012 Cengage Learning. All rights reserved.

Routers Routers - devices that enable multiple LANs to communicate with one another by forwarding packets from one LAN to another Copyright © 2012 Cengage Learning. All rights reserved.

Routers vs Switches Routers Switches Connect LANS Connect computers within a LAN IP addresses (Logical) MAC addresses (Physical) Work with packets Work with frames Do not forward broadcasts Do forward broadcasts Use routing tables Use switching tables Copyright © 2012 Cengage Learning. All rights reserved.

Routers Connect LANs It is possible to overload a LAN with computers Broadcast traffic can really affect this The next slide shows 3 different groups of users and 3 different servers all connected by switches Copyright © 2012 Cengage Learning. All rights reserved.

Routers Connect LANs Since they are connected by switches, they are all part of the same LAN and all broadcast traffic will be heard by all devices Copyright © 2012 Cengage Learning. All rights reserved.

Routers Connect LANs The picture on the next slide shows a better solution for the previous network The administrator groups users and servers together based on their department or function Copyright © 2012 Cengage Learning. All rights reserved.

Routers Connect LANs The router is used to create 3 separate LANs in order to contain broadcast traffic and facilitate more effective communication in each department LAN Copyright © 2012 Cengage Learning. All rights reserved.

Routers Create Broadcast Domains The scope of devices to which broadcast frames are forwarded is called a broadcast domain Each router interface in a network creates another broadcast domain Copyright © 2012 Cengage Learning. All rights reserved.

Routers Work with IP Addresses and Routing Tables Routers maintain routing tables composed of IP network addresses and interface pairs to determine where to forward packets on an internetwork Copyright © 2012 Cengage Learning. All rights reserved.

Routers Work with IP Addresses and Routing Tables What happens when a router isn’t connected to the network the packet is addressed to? The following slide shows what the routing table would look like on each router between the source and destination networks Copyright © 2012 Cengage Learning. All rights reserved.

Routers Work with IP Addresses and Routing Tables Copyright © 2012 Cengage Learning. All rights reserved.

Routers Work with IP Addresses and Routing Tables Default route — where to send a packet when the router doesn’t have an entry in its routing table Network unreachable — Message sent when the network can’t be found and there is no default route Default gateway — the IP address of the computer’s router Simulation 6: Router operation in a simple internetwork Copyright © 2012 Cengage Learning. All rights reserved.

Chapter Comprehension Check Network repeaters and hubs take incoming bit signals and repeat those signals out all connected ports Switches use _______ ______ to determine which MAC address can be found on which port switching tables A central device in a wireless network and perform a similar function to hubs Access points Create and mediate the connection between the computer and network medium Network interface cards Copyright © 2012 Cengage Learning. All rights reserved.

Chapter Comprehension Check Connect LANs to one another and forward packets from one LAN to another Router Routers use what address type to route messages between networks IP Address Unlike hubs and switches, routers do not forward broadcast frames The IP address of the computer’s router Default Gateway Copyright © 2012 Cengage Learning. All rights reserved.

Comprehension Check Used by the router to determine to which network to route packets Routing Table Where to send a packet when the router doesn’t have an entry in its routing table Default route Copyright © 2012 Cengage Learning. All rights reserved.

Lab As a class brainstorm labs that may make sense to do here. Copyright © 2012 Cengage Learning. All rights reserved.