Interconnecting Cisco Networking Devices Part 1 (ICND1) Course 01 - Building a Simple Network

Lesson 1 Networking Functions

Network Connections

Components of a Network

Looking at a Network Diagram

Applications Found on the Network Batch types of applications FTP, TFTP, Batch Reports, Inventory Updates Usually run at scheduled times Bandwidth is important, but not critical to the application Interactive Applications: Database queries or updates User to machine interactions Users look for quick response times, although important to the users experience, not that critical Real-time Applications: VoIP, video streams and conferencing Usually this is user to user interaction Latency must be avoided, real-time communications require very low latency on the network; this is critical for the application to work properly

Design Issues of a Network Topology Cost Speed Security Availability Scalability Reliability

Physical Topology Types Physical Topology refers to how the network devices are connected together The three basic categories are: Bus Star Mesh

Logical Topologies A logical topology is the path through the network for communications

Lesson 2 Understanding the Host-to-Host Communications Model

Examples of Host-to-Host Communications There are two different types of Host-to-Host Communications. The initial (older) model was: Usually proprietary (like Novell IPX/SPX) A 3 rd party application using communications software they developed Open Standards Model: OSI or TCP/IP stack both using a layered approach Multivendor software

OSI Reference Model Layer Number Name or Reference 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical

The TCP/IP Stack TCP/IP Stack Application Transport Internet Link

The Encapsulation Process Sender Application Transport Internet Network Access L2 HDR L3 HDR L3 HDR L4 HDR L4 HDR L4 HDR Other HDR Other HDR Other HDR L7-Data L7-Data L7-Data L7-Data FCS HDR = Header

Data De-Encapsulation Receiver Application Transport Internet Network Access L2 HDR L3 HDR L3 HDR L4 HDR L4 HDR L4 HDR Other HDR Other HDR Other HDR L7-Data L7-Data L7-Data L7-Data FCS HDR = Header

Communicating Peer-to-Peer PDUs Sender Application Transport Network Link Data Segment Packet Frame Receiver Application Transport Network Link

Lesson 3 Introducing LANs

Describing the LAN A Local Area Network (LAN) is usually described as: Equipment under your management High speed data connections Relatively close (geographically) connected devices

Components of the LAN User Devices PCs Servers Infrastructure Network Cards Physical Media Switches Routers Protocols Ethernet IP ARP DHCP

Understanding the Collision Domain

Understanding the Collision Domain (Cont.) The Layer 2 Switch should support the following functions: Operate at Layer 2 of the OSI and TCP/IP stack Ethernet Switches will either Forward, Flood, or Filter frames based on destination MAC Addresses Support Full-Duplex on its switchports Operate at high speeds, usually based on an ASIC architecture Auto sense speed and duplex settings

About the Switch Most Ethernet Switches have the following characteristics: High Port Density (compared to a router) Large frame buffers Auto sensing speed and duplex per port Fast internal switching Average a low cost per port

Lesson 4 Introduction to the IOS

Why the IOS The following are some of the features and functions of Cisco IOS: Connectivity to maintain high-speed traffic between devices Controlling access and unauthorized use Allowing for addition of interfaces and capability for network growth (scalability) Ensuring access to networked resources Consistency in user experience from one device to another

Basic Functions of the IOS The IOS is referred to as the CLI (Command Line Interface). Its purpose is to enter commands from the user. Operations, functions, and features can vary from one type of device to another Copy and Paste is available to the console/terminal window The Enter-key or Carriage Return instructs the IOS to parse and execute the typed command There are different modes of CLI operation, the EXEC and Configuration Modes Two default EXEC modes: User and Privileged

The User EXEC Mode This is the default mode available when a user first connects to a switch or router (assuming not password-protected) The command prompt will consist of the device host name followed by the greater than (>) sign

Privileged Exec Mode Often called Admin mode, and allows detailed examination of how a switch or router is operating This is the gateway to configuration mode Enables configuration and debugging To move from User Exec to Privileged Exec you must simply enter the command enable

Privileged EXEC Mode (Cont.) After switching to Privilege EXEC mode, the prompt will change to the hostname followed by a pound (#) sign: hostname#

Getting CLI Help CLI Help Options Context-Sensitive Help (using a?) Console Error Messages Description Lists all available commands and/or their supported arguments and parameters for that command Identifies if there is a problem with a command, to help the user identify how the command must be used or changed

Example of Using Context-Sensitive Help This sequence is showing how the? can provide context sensitive help:

Example Error Messages Ambiguous Not enough of a command was entered Incomplete More arguments/parameters are needed The caret ^ means that character was the first character that was not recognized as a valid command

Managing IOS Configurations Two general types of configurations: Startup Config: This is the last saved copy of the running configuration, which is generally loaded on device startup Absence of this file on a Router will launch the setup mode when the Router first powers on Running Config: The current configuration of the device. Running Configuration RAM Startup Configuration NVRAM Configuration Configuration

Viewing the Running-Config Using the show command, you can easily view the current running-configuration, but only if you re in the Privileged EXEC mode

Viewing the Startup-Config Startup-configuration is stored in the NVRAM, and can be viewed with the show command

Managing Cisco IOS Configuration tftp ftp scp http External Server

Managing the IOS Configuration Running Configuration RAM Copy running startup Copy startup running Configuration Configure Terminal (merge) Startup Configuration NVRAM Configuration Copy tftp: running (merge) Copy run tftp: Copy tftp: start Copy start tftp blank Erase start TFTP Server

Copy Options Saving the running-config to NVRAM Backup the running-config to a TFTP Server

E-MACS EMAC Command Tab Ctrl-A Ctrl-E Backspace Ctrl-U Ctrl-Shift-6 (same time) Ctrl-C Ctrl-Z Description Completes the typing of a command Moves to the beginning of a command Moves to the end of a command Removes one character to the left of the cursor Erases a line Aborts an IOS process such as ping or traceroute Aborts the current command and exits the configuration mode Returns you to Privileged EXEC from Configuration Mode

Improving the Use of the CLI You can utilize the previous command function to the last 10 commands. You can increase this with the terminal history size option. The show history command will show you the last X commands you ve entered.

Improving the Use of the CLI (Cont.) If the content of a show command is long, you ll see the output pause, and a More option listed at the bottom of the display Pressing Enter will show you the next line of the output Pressing spacebar will show you the next page This setting can be adjusted as follows:

Improving the Use of the CLI (Cont.) You can filter the output of a show command through the use of pipes ( ) Common filters would be the include or the section options

Lesson 5 Starting a Switch

Installing the Switch Prior to installation, verify the environment is ready (Power and/or Cooling) Physically install the switch Rack/Wall Mounts Table/Shelf mount Verify the cabling is correct Plug the switch in, then power it on System will go through normal startup processes such as POST and Bootstrap

Understanding the LED Indicators The following are the LED Indicators 1: System LED 2: Remote Power Supply LED 3-6: Port Mode LEDs 7: Mode Button 8: Port Status LED

Initial Console Connection To make the initial connection you will need: To find the console port A console cable (Optionally) a USB-to-Serial port adapter

Configuration Basics From privileged EXEC mode, you would need to enter configuration mode using the command configure terminal For more specific configuration options, you must navigate to that configuration hierarchy, for instance to an interface configuration mode if you wanted to change the interface configuration

Configuration Basics (Cont.) Using the hostname command to change the local identity of the switch This will also be displayed with the prompt

Configuration Basics (Cont.) Assign the default management IP address, including subnet mask for a switch You may still have to issue the no shutdown command even though the VLAN 1 interface is virtual

Viewing the Initial Startup Status The show version command is useful to see the system hardware, software version, serial numbers, and boot images in use

Viewing the Initial Startup Status (Cont.) You can verify interface statistics by using the show interface command

Viewing the Initial Startup Status (Cont.) Viewing the active (running) configuration on the switch

Lesson 6 Understanding Ethernet and Switch Operation

Media for Ethernet All transmissions consist of some method to transmit binary 1 s and 0 s. The mechanics of how that works depends on the physical media type. Coaxial (no longer used in the Enterprise) Copper (such as twisted pair) Fiber-optic Ethernet is a means of encoding information for transmission, most often for sharing files and other types of communication

Media for Ethernet (Cont.) Ethernet was modified to the twisted pair, like with the use of telephone wiring to reduce costs UTP (Unshielded Twisted Pair), which is 4-pairs of copper wires twisted together, became widely popular Starting with 10BASE-T (stood for 10Mbs, Baseband, over Twisted pair) Fiber-optic variants of Ethernet have a higher performance, signals can travel further (sometimes in the tens of kilometers), and have electrical isolation

Media for Ethernet (Cont.) The most popular media for the small enterprise is the UTP option RJ-45 Connector Outer Jacket Color Coded Plastic Insulation Characteristic Speed or Bandwidth Price Media and connector size Maximum cable run Value Between 10Mb/s to 10 Gb/s Least Expensive Option Small Varies on Bandwidth and CAT Type

Media for Ethernet (Cont.) RJ-45 Connector and the RJ-45 Jack

Media for Ethernet (Cont.) Single Mode Optical Fiber Example

Media for Ethernet (Cont.)

Media for Ethernet (Cont.) Types of Fiber Cable Connectors

Ethernet Frames Size in Bytes The Ethernet Frame 8 6 6 2 46-1500 4 Content Preamble Destination MAC Source MAC Ether- Type Data Frame Check Sequence

Communication Types Unicast Broadcast Multicast Example of a Client Group

Introducing the MAC Address The Ethernet MAC Address is 48bits in size (6 bytes) The first 24bits (3 bytes) is the OUI The last 24bits (3 bytes) is Vendor Assigned OUI 24 bits Vendor Assigned 24 bits

Introducing the MAC Address (Cont.) Depending on the vendor s software, the MAC Address may be displayed in different formats This is still a hexadecimal value, it s only the display that looks different 0000.0c43.2e08 (dots separation) 00:00:0c:43:2e:08 (colon between each 8 bits) 00-00-0c-43-2e-08 (hyphen separating each 8 bits)

How the Switch Works frame 1 MAC Table Port 1: MAC A Port 2: Empty Port 3: Empty 2 3 MAC Table Port 1: MAC A Port 2: Empty Port 3: Empty frame 1 frame 2 3

How the Switch Works (Cont.) 1 MAC Table Port 1: MAC A Port 2: Empty Port 3: MAC - B 2 3 frame MAC Table Port 1: MAC A Port 2: Empty Port 3: MAC - B frame 1 2 3

Understanding Duplex Half-Duplex means: You can transmit or receive, but not at the same time This is unidirectional communications Older technology

Understanding Duplex (Cont.) Full-Duplex operation: Point to Point only, no shared media Both ends must support full-duplex

Configuring Duplex and Speed This example shows you how to manually configure speed and duplex for interface FastEthernet 0/1 The next part of that configuration shows you how to set autoduplex and auto-speed on interface FastEthernet 0/5

Results of Duplex Settings Duplex Setting Half Full Auto Half Half Mismatch Half Full Mismatch Full Full Auto Half Full Full

Results of Duplex/Speed Settings The Show Interface command will allow you to view the current duplex and speed on an interface

Lesson 7 Troubleshooting Common Switch Media Issues

Troubleshooting Tools Using PING to test connectivity

Troubleshooting Tools (Cont.) Telnet can test connectivity to the application layer

Problems with Media Copper media can have several issues that cause problems: EMI sources causing noise Damage to the cable itself Change in traffic flow causing congestion Installation of new equipment

Problems with Media (Cont.) Fiber can also have issues that affect communications: Macrobend losses: Fiber can t be bent into too small a radius or light can escape This means that the light does not reflect correctly off of the cladding, which could lead to loss of light Improper splicing also causes loss of light Radius greater than 25-30mm = No Loss

Troubleshooting Flow Chart

Understanding Interface Status Using show interface command Interface Status Line Protocol Status Link State Up Up Operational Up Down Connection issue Down Down (not connected) Cable unplugged, or other side is disconnected or shut down Down Down Interface problem Administratively Down Down Disabled

Understanding Interface Statistics Excessive collisions: This naturally occurs with half-duplex Try to change to full-duplex Change both sides to have the same duplex settings Excessive late collisions: Usually a duplex mismatch Configure the link to use full-duplex Change both sides to have the same duplex settings Excessive Noise: Usually indicated by too many CRC errors Check cable for damage or excessive length There may also be another source of noise, such as electrical devices too close

Interface Statistics Interface Statistics

Port Problems Most common port problems can be associated with duplex and speed mismatches Verify the duplex settings match on both ends of the cable Verify the speed settings match on both ends of the cable

Port Problems (Cont.) Some examples of the duplex mismatches are: One end set to half, the other end set to full One end set to full, the other set to auto If Auto-Negotiation fails, it will default to half One end set to half, the other set to auto If Auto-Negotiation fails, it will default to half No mismatch would then occur

Port Problems (Cont.) Other duplex examples are: Autonegotiation is set on both ends: One side fails to full duplex, and the other end fails to half duplex A Gigabit Ethernet interface defaults to full duplex, while a 10/100 defaults to half duplex Autonegotiation is set on both ends: If both sides fail to half, then there is no mismatch Autonegotiation fails on both ends, and they both revert to half duplex

Port Problems (Cont.) Here are some of the issues relating to speed settings: Each end is set to a different speed then a mismatch occurs One side set to a specific speed, the other side set to auto If auto-negotiation fails, switch will sense what the other side is using to revert to the best speed Auto is set on both ends Auto fails on both sides, they then revert to their slowest speed and then there would be no mismatch

Troubleshooting Flow Chart Follow this flow chart for troubleshooting port setting issues:

Troubleshooting Port Issues Display the duplex and speed settings with the show interface command

Review Questions: 1. You download a file from an FTP site on the Internet. What is the highest layer in the OSI model used in this FTP operation? A. Application B. Presentation C. Session D. Transport 2. A host computer has been correctly configured with a static IP address, but the default gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error? A. Layer 1 B. Layer 2 C. Layer 3 D. Layer 4 3. Which layer of the OSI reference model is responsible for ensuring reliable endto-end delivery of data? A. Application B. Presentation C. Session D. Transport 4. In the communications industry, what are the features and benefits of using the layered OSI model? A. It encourages industry standardization by defining what functions occur at each layer of the model B. It necessitates changes in functionality in one layer to other layers C. It enables equipment efficiency from different vendors to use the same electronic components D. It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting E. A & B F. C & D G. A & D

5. At which layer of the OSI model is the optimal path to a network destination determined at? A. Data Link B. Session C. Physical D. Network 6. Which OSI layer header contains the address of a destination host that is another network? A. Application B. Presentation C. Network D. Transport 7. A network device connects to the network through an interface for the corresponding media type. This device is known as a NIC; what does NIC stand for? A. Next Interchange Connection B. Network Interface Card C. Now In Charge D. Network Independent Charge 8. A kilobyte is how many bytes? A. 1,000 B. 1,000,000 C. 100 D. 10,000 9. When moving from the upper layers of the OSI model to the lower layers, the information for each layer is added on as headers, and this process is known as what? A. De-encapsulation B. Packet Padding C. Encapsulation D. Compression

10. What layer of the OSI model do the protocols Ethernet, PPP, and frame-relay operate on? A. Layer 4 B. Layer 3 C. Layer 2 D. Layer 1

Answer Key: 1. A The highest layer in the OSI model is layer 7, the Application layer. This layer describes the use of end-user applications, such as Microsoft Office applications, Internet browsers, Telnet, and FTP. 2. C IP Addressing and IP Routing reside on the OSI Network layer, which is layer 3. 3. D A key function of the Transport layer is to provide connection services for the protocols and applications that run at the levels above it. Transport layer protocols are given intelligence in the form of algorithms that ensure reliable and efficient communication between devices. This encompasses several related jobs, including lost transmission detection and handling, and managing the rate at which data is sent, to ensure that the receiving device is not overwhelmed. 4. G The OSI (Open System Interconnection) reference model was created as a reference point for communications devices. A layered approach is used to segment the entire telecommunications process into a series of smaller steps. A is correct because it encourages a level of standardization by encouraging that functions be compared to known layers. D is also correct because it allows engineers to focus on the development, refining, and perfection of simpler components. 5. D The Network layer (Internet layer in the TCP/IP model) provides logical addressing and routing through an internetwork. The Network layer is layer 3 of the OSI model. 6. C Only network address contains this information. To transmit the packets, the sender uses network address and data link address. But the layer 2 address represents just the address of the next hop device on the way to the sender, and is changed on each hop. Network address remains the same.

7. B This is an interface to the appropriate network media, hence the name Network Interface Card. 8. A This is 1,000 bytes; kilo stands for 1000. Technically, this is really 2 to the power of 10, which is really 1024 bytes, but in practice, we round this down to 1000 based on the prefix of KILO. 9. C Encapsulation describes the method of putting these headers around the original data as the data moves down the stack. 10. C These are all layer 2 encapsulation protocols.