About the Author

Scott Empson is the associate chair of the Bachelor of Applied Information Systems Technology degree program at the Northern Alberta Institute of Technology in Edmonton, Alberta, Canada, where he teaches Cisco routing, switching, and network design courses in a variety of different programs (certificate, diploma, and applied degree) at the post-secondary level. Scott is also the program coordinator of the Cisco Networking Academy Program at NAIT, a Regional Academy covering Central and Northern...

Acknowledgments

Anyone who has ever had anything to do with the publishing industry knows that it takes many, many people to create a book. It may be my name on the cover, but there is no way that I can take credit for all that occurred to get this book from idea to publication. Therefore, I must thank The team at Cisco Press Once again, you amaze me with your professionalism and the ability to make me look good. Mary Beth, Chris, Patrick, Meg, Seth thank you for your continued support and belief in my little...

Applying Extended ACLs to an Interface

Router(config) interface fastethernet 0 0 Router(config-if) ip access-group 110 out TIP Access lists can be applied in either an inbound direction (keyword in) or in an outbound direction (keyword out). TIP Only one access list can be applied per interface, per direction. TIP Apply an extended ACL as close as possible to the source network or device.

Assigning IPv6 Addresses to Interfaces

Enables the forwarding of IPV6 unicast datagrams globally on the router. Router(config) interface fastethernet 0 0 Moves to interface configuration mode. Automatically configures an IPv6 link-local address on the interface and enables IPv6 processing on the interface. NOTE The link-local address that the ipv6 enable command configures can be used only to communicate with nodes on the same link. Router(config-if) ipv6 address 3000 1 64 Configures a global IPv6 address on the interface and...

Assigning Ports to VLANs

Switch(config) interface fastethernet 0 1 Moves to interface configuration mode Switch(config-if) switchport mode access Switch(config-if) switchport access vlan 10 NOTE When the switchport mode access command is used, the port operates as a nontrunking, single VLAN interface that transmits and receives nonencapsulated frames. An access port can belong to only one VLAN.

Binary ANDing

Binary ANDing is the process of performing multiplication to two binary numbers. In the decimal numbering system, ANDing is addition 2 and 3 equals 5. In decimal, there are an infinite number of answers when ANDing two numbers together. However, in the binary numbering system, the AND function yields only two possible outcomes, based on four different combinations. These outcomes, or answers, can be displayed in what is known as a truth table You use ANDing most often when comparing an IP...

Cables and Connections

This chapter provides information and commands concerning the following topics Connecting a rollover cable to your router or switch Determining what your terminal settings should be Understanding the setup of different LAN connections Identifying different serial cable types Determining which cable to use to connect your router or switch to another device

Changing the Spanning Tree Mode

Different types of spanning tree can be configured on a Cisco switch. The options vary according to the platform Per-VLAN Spanning Tree (PVST) There is one instance of spanning tree for each VLAN. This is a Cisco proprietary protocol. Per-VLAN Spanning Tree Plus (PVST+) Also Cisco proprietary. Has added extensions to the PVST protocol. Rapid PVST+ This mode is the same as PVST+ except that it uses a rapid convergence based on the 802.1w standard. Multiple Spanning Tree Protocol (MSTP) IEEE...

STP and Ether Channel 139

Enabling Spanning Tree Protocol 139 Configuring the Root Switch 140 Configuring a Secondary Root Switch 141 Configuring Port Priority 141 Configuring the Path Cost 142 Configuring the Switch Priority of a VLAN 142 Configuring STP Timers 143 Verifying STP 143 Optional STP Configurations 144 Changing the Spanning-Tree Mode 145 Extended System ID 146 Enabling Rapid Spanning Tree 146 Troubleshooting Spanning Tree 147 Configuration Example STP 147 EtherChannel 150 Interface Modes in EtherChannel 151...

Backing Up and Restoring Cisco IOS Software and Configurations 185

Backing Up Configurations to a TFTP Server 186 Restoring Configurations from a TFTP Server 187 Backing Up the Cisco IOS Software to a TFTP Server 188 Restoring Upgrading the Cisco IOS Software from a TFTP Server 188 Restoring the Cisco IOS Software from ROM Monitor Mode Using Xmodem 189 Restoring the Cisco IOS Software Using the ROM Monitor Environmental Variables and tftpdnld Command 192

HDLC and PPP 251

Configuring HDLC Encapsulation on a Serial Line 251 Configuring PPP on a Serial Line (Mandatory Commands) 251 Configuring PPP on a Serial Line (Optional Commands) Compression 252 Configuring PPP on a Serial Line (Optional Commands) Link Quality 252 Configuring PPP on a Serial Line (Optional Commands) Multilink 252 Configuring PPP on a Serial Line (Optional Commands) Authentication 252 Verifying or Troubleshooting a Serial Link PPP Encapsulation 253 Configuration Example PPP 254

IP Access Control List Security 269

Applying Standard ACLs to an Interface 272 Applying Extended ACLs to an Interface 275 The established Keyword (Optional) 275 Using Sequence Numbers in Named ACLs 276 Removing Specific Lines in Named ACLs Using Sequence Numbers 277 Sequence Number Tips 278 Including Comments About Entries in ACLs 278 Restricting Virtual Terminal Access 279 Configuration Examples ACLs 279

Security Device Manager 283

Security Device Manager Connecting with CLI 283 Security Device Manager Connecting with GUI 285 SDM Express Wizard with No CLI Preconfiguration 287 Resetting the Router to Factory Defaults Using SDM 297 SDM User Interfaces 298 Configuring Interfaces Using SDM 298 Configuring Routing Using SDM 302 SDM Monitor Mode 304 Using SDM to Configure a Router to Act as a DHCP Server 305 Using SDM to Configure an Interface as a DHCP Client 307 Using SDM to Configure NAT PAT 312 What to Do If You Lose SDM...

Configuring a Single Cisco Router

Entering Global Configuration Mode 54 Configuring a Fast Ethernet Interface 59 Creating a Message-of-the-Day Banner 60 Assigning a Local Host Name to an IP Address 61 EXEC Commands in Configuration Mode The do Command 64 Configuration Example Basic Router Configuration 64

Class AE Addresses

All 0s in host portion Network or subnetwork address All 1s in host portion Broadcast address Combination of 1s and 0s in host portion Valid host address All 0s in host portion Network or subnetwork address All 1s in host portion Broadcast address Combination of 1s and 0s in host portion Valid host address

Command Modes

Displays information about software and hardware. Displays information about flash memory (for the 2900 2950 series only). Displays the current MAC address forwarding table. switch show controllers ethernet-controller Displays information about the Ethernet controller. Displays the current configuration in DRAM. Displays the current configuration in NVRAM. Displays whether the switch passed POST. Displays the current VLAN configuration. Displays the interface configuration and status of line up...

Command Syntax Conventions

The conventions used to present command syntax in this book are the same conventions used in the Cisco IOS Command Reference. The Command Reference describes these conventions as follows Boldface indicates commands and keywords that are entered literally as shown. In actual configuration examples and output (not general command syntax), boldface indicates commands that are manually input by the user (such as a show command). Italics indicate arguments for which you supply actual values....

Configuration Example

Figure 11-1 shows the network topology for the basic configuration of a 2960 series switch using commands covered in this chapter. Figure 11-1 Network Topology for 2960 Series Switch Configuration Turns off Domain Name System (DNS) queries so that spelling mistakes do not slow you down. Sets the encrypted secret password to cisco. 2960(config-line) logging synchronous Appends commands to a new line router information will not interrupt. User must log in to console before use. Moves back to...

Configuration Example DHCP

Figure 24-1 illustrates the network topology for the configuration that follows, which shows how to configure DHCP services on a Cisco IOS router using the commands covered in this chapter. Figure 24-4 Network Topology for DHCP Configuration Figure 24-4 Network Topology for DHCP Configuration Edmonton(config) interface fastethernet 0 0 Moves to interface configuration mode Edmonton(config-if) description LAN Interface Sets the local description of the interface Edmonton(config-if) ip address...

Configuration Example PPP

Figure 26-1 illustrates the network topology for the configuration that follows, which shows how to configure PPP using the commands covered in this chapter. Figure 26-1 Network Topology for PPP Configuration Figure 26-1 Network Topology for PPP Configuration NOTE The host name, password, and interfaces have all been configured as per the configuration example in Chapter 6, Configuring a Single Cisco Router. Boston(config) username Buffalo password academy Sets the local username and password...

Configuration Example STP

Figure 14-1 illustrates the network topology for the configuration that follows, which shows how to configure STP using commands covered in this chapter. Figure 14-4 Network Topology for STP Configuration Example Figure 14-4 Network Topology for STP Configuration Example Turns off Dynamic Name System (DNS) queries so that spelling mistakes do not slow you down. Changes the switch to VTP server mode. This is the default mode. Configures the VTP domain name to stpdemo. Creates VLAN 10 and enters...

Configuration Example VLANs

Figure 12-1 illustrates the network topology for the configuration that follows, which shows how to configure VLANs using the commands covered in this chapter. Figure 12-2 Network Topology for VLAN Configuration Example Creates VLAN 10 and enters VLAN configuration mode. Increases the revision number by 1 and returns to global configuration mode. Creates VLAN 20 and enters VLAN configuration mode. Creates VLAN 30 and enters VLAN configuration mode. Note that you do not have to exit back to...

Configuring a DHCP Helper Address

Router(config) interface fastethernet 0 0 Moves to interface configuration mode. Router(config-if) ip helper-address 172.16.20.2 DHCP broadcasts will be forwarded as a unicast to this specific address rather than be dropped by the router. NOTE The ip helper-address command will forward broadcast packets as a uni-cast to eight different UDP ports by default NetBIOS name server (port 137) NetBIOS datagram server (port 138) Boot Protocol (BOOTP) client and server datagrams (ports 67 and 68) If you...

Configuring a Secondary Root Switch

Switch(config) spanning-tree vlan 5 root secondary Switch recalculates timers along with priority to allow the switch to become the root switch for VLAN 5 should the primary root switch fail. NOTE If all other switches have extended system ID support, this switch resets its priority to 28672. Therefore, if the root switch fails, and all other switches are set to the default priority of 32768, this becomes the new root switch. For switches without extended system ID support, the switch priority...

Configuring DHCP

Router(config) ip dhcp pool internal Creates a DHCP pool called internal. Router(dhcp-config) network 172.16.10.0 255.255.255.0 Defines the range of addresses to be leased. Router(dhcp-config) default-router 172.16.10.1 Defines the address of the default router for the client. Router(dhcp-config) dns-server 172.16.10.10 Defines the address of the Domain Name System (DNS) server for the client 172.16.10.10 Defines the address of the NetBIOS server for the client. Router(dhcp-config) domain-name...

Configuring Frame Relay

Setting the Frame Relay Encapsulation Type Router(config) interface serial 0 0 0 Router(config-if) encapsulation frame-relay Turns on Frame Relay encapsulation with the default encapsulation type of cisco. Router(config-if) encapsulation frame-relay ietf Turns on Frame Relay encapsulation with the encapsulation type of ietf (RFC 1490). Use the ietf encapsulation method if connecting to a non-Cisco router. Setting the Frame Relay Encapsulation LMI Type Router(config-if) frame- relay lmi-type...

Configuring HDLC Encapsulation on a Serial Line

Router(config) interface serial 0 0 0 Moves to interface configuration mode Router(config-if) encapsulation hdlc Sets the encapsulation mode for this interface to HDLC NOTE HDLC is the default encapsulation for synchronous serial links on Cisco routers. You would only use the encapsulation hdlc command to return the link to its default state.

Configuring Layer 2 Ether Channel

Switch(config) interface range fastethernet 0 1 - 4 Moves to interface range configuration mode. pagp Specifies the PAgP protocol to be used in this channel. lacp Specifies the LACP protocol to be used in this channel. 1 mode desirable I auto I on I passive I active Creates channel group 1 and assigns interfaces 01-04 as part of it. Use whichever mode is necessary, depending on your choice of protocol.

Configuring Static NAT One Private to One Permanent Public Address Translation

Step 1 Define a static route on the remote router stating where the public addresses should be routed. ISP(config) ip route 64.64.64.64 255.255.255.128 s0 0 Informs the ISP where to send packets with addresses destined for 64.64.64.64 255.255.255.128. Step 2 Create a static mapping on your router that will perform NAT. Corp(config) ip nat inside source static 172.16.10.5 64.64.64.65 Permanently translates the inside address of 172.16.10.5 to a public address of 64.64.64.65. Use the command for...

Configuring STP Timers

Switch(config) spanning-tree vlan 5 hello-time 4 Changes the hello-delay timer to 4 seconds on VLAN 5 Switch(config) spanning-tree vlan 5 forward-time 20 Changes the forward-delay timer to 20 seconds on VLAN 5 Switch(config) spanning-tree vlan 5 max-age 25 Changes the maximum-aging timer to 25 seconds on VLAN 5 NOTE For the hello-time command, the range is 1 to 10 seconds. The default is 2 seconds. For the forward-time command, the range is 4 to 30 seconds. The default is 15 seconds. For the...

Configuring the Switch Priority of a VLAN

NOTE With the priority keyword, the range is 0 to 61440 in increments of 4096. The default is 32768. The lower the priority, the more likely the switch will be chosen as the root switch. Only the following numbers can be used as a priority value CAUTION Cisco recommends caution when using this command. Cisco further recommends that the spanning-tree vlan x root primary or the spanning-tree vlan xroot secondary command be used instead to modify the switch priority.

Contents at a Glance

Part II Introduction to Cisco Devices 35 Chapter 5 The Command-Line Interface 45 Chapter 6 Configuring a Single Cisco Router 53 Chapter 13 VLAN Trunking Protocol and Inter-VLAN Routing 125 Chapter 15 Implementing a Wireless LAN 161 Part VII Network Administration and Troubleshooting 183 Chapter 16 Backing Up and Restoring Cisco IOS Software and Configurations 185 Chapter 17 Password-Recovery Procedures and the Configuration Register 193 Chapter 18 Cisco Discovery Protocol (CDP) 201 Chapter 20...

Converting Between Decimal Numbers and Binary

In any given octet of an IP address, the 8 bits can be defined as follows To convert a decimal number into binary, you must turn on the bits (make them a 1) that would add up to that number, as follows 187 10111011 128+32+16+8+2+1 224 11100000 128+64+32 To convert a binary number into decimal, you must add the bits that have been turned on (the 1s), as follows 10101010 128+32+8+2 170 11110000 128+64+32+16 240 The IP address 138.101.114.250 is represented in binary as The subnet mask of...

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Creating Named ACLs

Router(config) ip access-list extended serveraccess Creates an extended named ACL called serveraccess and moves to named ACL configuration mode. Router(config-ext-nacl) permit tcp any host 131.108.101.99 eq smtp Permits mail packets from any source to reach host 131.108.101.99. Router(config-ext-nacl) permit udp any host 131.108.101.99 eq domain Permits Domain Name System (DNS) packets from any source to reach host 131.108.101.99. Router(config-ext-nacl) deny ip any any log Denies all other...

Dynamic Trunking Protocol DTP

Switch (config) interface fastethernet 0 1 Moves to interface configuration mode. Switch(config-if) switchport mode dynamic desirable Makes the interface actively attempt to convert the link to a trunk link. NOTE With the switchport mode dynamic desirable command set, the interface becomes a trunk link if the neighboring interface is set to trunk, desirable, or auto. Makes the interface able to convert into a trunk link. NOTE With the switchport mode dynamic auto command set, the interface...

Enabling Rapid Spanning Tree

Switch(config) spanning-tree mode rapid-pvst Switch(config) interface fastethernet 0 1 Moves to interface configuration mode. Switch(config-if) spannisng-tree link-type point-to-point Sets the interface to be a point-to-point interface. NOTE By setting the link type to point to point, this means that if you connect this port to a remote port, and this port becomes a designated port, the switch negotiates with the remote port and transitions the local port to a forwarding state. Switch(config)...

Erasing VLAN Configurations

Removes the entire VLAN database from flash. WARNING Make sure there is no space between the colon ( ) and the characters vlan.dat. You can potentially erase the entire contents of the flash with this command if the syntax is not correct. Make sure you read the output from the switch. If you need to cancel, press to escape back to privileged mode (Switch ) Delete filename vlan.dat Delete flashivlan.dat confirm Switch Switch(config) interface fastethernet 0 5 Moves to interface configuration...

Example for Understanding Route Summarization

Refer to Figure 3-1 to assist you as you go through the following explanation of an example of route summarization. Figure 3-1 Four-City Network Without Route Summarization As you can see from Figure 3-1, Winnipeg, Calgary, and Edmonton each have to advertise internal networks to the main router located in Vancouver. Without route summarization, Vancouver would have to advertise 16 networks to Seattle. You want to use route summarization to reduce the burden on this upstream router.

Extended System ID

Switch(config) spanning-tree extend system-id Enables extended system ID, also known as MAC address reduction. NOTE Catalyst switches running software earlier than Cisco IOS Software Release 12.1(8) EA1 do not support the extended system ID. Verifies extended system ID is enabled. Verifies extended system ID is enabled.

Feedback Information

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Frame Relay

This chapter provides information and commands concerning the following topics Setting the Frame Relay encapsulation type Setting the Frame Relay encapsulation LMI type Setting the Frame Relay DLCI number Configuring a Frame Relay map statement Configuring a description of the interface (optional) Configuring Frame Relay using subinterfaces Troubleshooting Frame Relay Configuration examples Frame Relay

Guidelines for Configuring Ether Channel

You can combine from two to eight parallel links. All ports must be identical Cannot mix Fast Ethernet and Gigabit Ethernet Must all be VLAN trunk or nontrunk operational status All links must be either Layer 2 or Layer 3 in a single channel group. To create a channel in PAgP, sides must be set to To create a channel in LACP, sides must be set to To create a channel without using PAgP or LACP, sides must be set to On-On. Do not configure a GigaStack gigabit...

HDLC and PPP

This chapter provides information and commands concerning the following topics Configuring HDLC encapsulation on a serial line Configuring PPP on a serial line (mandatory commands) Configuring PPP on a serial line (optional commands), including those commands concerning the following Verifying or troubleshooting a serial link PPP encapsulation

Hj wirelessN

This Setup Wizard will help you install the Wireless-N Broadband Router. Norton Internet Security User Guide Exit 200S Cisco Systems. Inc. All Rights Reserved Figure 15-3 shows the wizard asking you to unplug the power from your modem. When you have finished, click Next. Figure 15-8 Unplugging Power to the Modem Figure 15-8 Unplugging Power to the Modem Figure 15-4 shows the wizard asking you to unplug the modem from your computer. When you have finished, click...

Implementing a Wireless LAN

This chapter provides information and commands concerning the following topics Wireless access point configuration Linksys 300N access point Wireless client configuration Linksys Wireless-N Notebook Adapter NOTE This chapter contains information that is not part of the objective list of knowledge needed for passing the CCNA 640-901 certification exam. However, the Cisco Networking Academy Program has included these topics as part of its curriculum. Therefore, this chapter is provided to you as...

Including Comments About Entries in ACLs

Router(config) access-list 10 remark only Jones has access The remark command allows you to include a comment (limited to 100 characters). Router(config) access-list 10 permit 172.16.100.119 Read this line to say, Host 172.16.100.119 will be permitted through the internetwork. Router(config) ip access-list extended telnetaccess Creates a named ACL called telnetaccess and moves to named ACL configuration mode. Router(config-ext-nacl) remark do not let Smith have telnet The remark command allows...

Interface

This chapter provides information and commands concerning the following topics Shortcuts for entering commands Using the fTabj) key to enter complete commands Using the question mark for help enable command exit command disable command logout command Setup mode Keyboard help History commands show commands To enhance efficiency, Cisco IOS Software has some shortcuts for entering commands. Although these are great to use in the real world, when it comes time to write a vendor exam, make sure you...

Interface Modes in Ether Channel

Forces the interface into an EtherChannel without PAgP or LACP. Channel only exists if connected to another interface group also in On mode. Places the interface into a passive negotiating state will respond to PAgP packets but will not initiate PAgP negotiation. Places the interface into an active negotiating state will send PAgP packets to start negotiations. Places the interface into a passive negotiating state will respond to LACP packets but will not initiate LACP negotiation. Places the...

InterVLAN Communication Tips

Although most routers support both ISL and dot1q encapsulation, some switch models only support dot1q (the 2950 and 2960 series, for example). If you need to use ISL as your trunking protocol, use the command encapsulation isl x, where x is the number of the VLAN to be assigned to that subinterface. Recommended best practice is to use the same number of the VLAN number for the subinterface number. It is easier to troubleshoot VLAN 10 on subinterface fa0 0.10 than on fa0 0.2. The native VLAN...

InterVLAN Communication Using an External Router Routerona Stick

Router(config) interface fastethernet O O Moves to interface configuration mode. Router(config-if) interface fastethernet 0 0.1 Creates subinterface 0 0.1 and moves to subinterface configuration mode. Router(config-subif) description Management VLAN 1 (Optional) Sets the locally significant description of the subinterface. Router(config-subif) encapsulation dot1q 1 native Assigns VLAN 1 to this subinterface. VLAN 1 will be the native VLAN. This subinterface will use the 802.1q trunking...

IP Access Control List Security

This chapter provides information and commands concerning the following topics Applying standard ACLs to an interface Applying extended ACLs to an interface The established keyword (optional) Using sequence numbers in named ACLs Removing specific lines in named ACLs using sequence numbers Including comments about entries in ACLs Restricting virtual terminal access Configuration examples ACLs

IP Subnet Zero

When you work with classical subnetting, you always have to eliminate the subnets that contain either all zeros or all ones in the subnet portion. Hence, you always used the formula 2N - 2 to define the number of valid subnets created. However, Cisco devices can use those subnets, as long as the command ip subnet-zero is in the configuration. This command is on by default in Cisco IOS Software Release 12.0 and later if it was turned off for some reason, however, you can re-enable it by using...

Pv6 Ping

To diagnose basic network connectivity using IPv6 to the specified address, enter the following command The following characters can be displayed as output when using PING in IPv6. Each exclamation point indicates receipt of a reply. Each period indicates that the network server timed out while waiting for a reply. Administratively unreachable. Usually means that an access control list (ACL) is blocking traffic. Chapter 26 HDLC and PPP Chapter 27 Frame Relay

Networking Devices Used in the Preparation of This Book

To verify the commands in this book, I had to try them out on a few different devices. The following is a list of the equipment I used when writing this book C2620 router running Cisco IOS Software Release 12.3(7)T, with a fixed Fast Ethernet interface, a WIC-2A S serial interface card, and an NM-1E Ethernet interface C2821 ISR with PVDM2, CMME, a WIC-2T, FXS and FXO VICs, running 12.4(10a) IPBase IOS WS-C2960-24TT-L Catalyst Switch, running 12.2(25)SE IOS WS-C2950-12 Catalyst switch, running...

Optional STP Configurations

Although the following commands are not mandatory for STP to work, you might find these helpful to fine-tune your network. Switch(config) interface fastethernet 0 10 Moves to interface configuration mode. Switch(config-if) spanning-tree portfast Switch(config-if) spanning-tree portfast trunk WARNING Use the portfast command only when connecting a single end station to an access or trunk port. Using this command on a port connected to a switch or hub could prevent spanning tree from detecting...

Organization of This Book

This book follows what I think is a logical approach to configuring a small to mid-size network. It is an approach that I give to my students when they invariably ask for some sort of outline to plan and then configure a network. Specifically, this approach is as follows Chapter 1, How to Subnet An overview of how to subnet, examples of subnetting (both a Class B and a Class C address), the use of the binary AND operation, the Enhanced Bob Maneuver to Subnetting Chapter 2, VLSM An overview of...

Private Addressing Used in this Book

This book makes use of RFC 1918 addressing throughout. Because I do not have permission to use public addresses in my examples, I have done everything with private addressing. Private addressing is perfect for use in a lab environment or in a testing situation, because it works exactly like public addressing, with the exception that it cannot be routed across a public network. That is why you will see private addresses in my WAN links between two routers using serial connections, or in my Frame...

Requirements for Route Summarization

To create route summarization, there are some necessary requirements Routers need to be running a classless routing protocol, as they carry subnet mask information with them in routing updates. (Examples are RIP v2, OSPF, EIGRP, IS-IS, and BGP.) Addresses need to be assigned in a hierarchical fashion for the summarized address to have the same high-order bits. It does no good if Winnipeg has network 172.16.64.0 and 172.16.67.0 while 172.16.65.0 resides in Calgary and 172.16.66.0 is assigned in...

Restricting Virtual Terminal Access

Router(config) access-list 2 permit host 172.16.10.2 Permits host 172.16.10.2 to Telnet into this router based on where this ACL is applied. Router(config) access-list 2 permit 172.16.20.0 0.0.0.255 Permits anyone from the 172.16.20.x address range to Telnet into this router based on where this ACL is applied. The implicit deny statement restricts anyone else from being permitted to Telnet. Moves to vty line configuration mode. Router(config-line)access-class 2 in Applies this ACL to all 5 vty...

Route Summarization

Route summarization, or supernetting, is needed to reduce the number of routes that a router advertises to its neighbor. Remember that for every route you advertise, the size of your update grows. It has been said that if there were no route summarization, the Internet backbone would have collapsed from the sheer size of its own routing tables back in 1997 Routing updates, whether done with a distance vector or link-state protocol, grow with the number of routes you need to advertise. In simple...

Route Summarization and Route Flapping

Another positive aspect of route summarization has to do with route flapping. Route flapping is when a network, for whatever reason (such as interface hardware failure or misconfiguration), goes up and down on a router, causing that router to constantly advertise changes about that network. Route summarization can help insulate upstream neighbors from these problems. Consider router Edmonton from Figure 3-1. Suppose that network 172.16.74.0 24 goes down. Without route summarization, Edmonton...

Routing

Chapter 7 Static Routing Chapter 8 RIP Chapter 9 EIGRP Chapter 10 Single Area OSPF This chapter provides information and commands concerning the following topics Configuring a static route on a router The permanent keyword (optional) Static routes and administrative distance (optional) Configuring a default route on a router Configuration example Static routes Configuring a Static Route on a Router When using the ip route command, you can identify where packets should be routed in two ways Both...

Saving VLAN Configurations

The configurations of VLANs 1 through 1005 are always saved in the VLAN database. As long as the apply or the exit command is executed in VLAN database mode, changes are saved. If you are using VLAN configuration mode, the exit command saves the changes to the VLAN database, too. If the VLAN database configuration is used at startup, and the startup configuration file contains extended-range VLAN configuration, this information is lost when the system If you are using VTP transparent mode, the...

Security Device Manager

This chapter provides information and commands concerning the following topics Security Device Manager Connecting with CLI Security Device Manager Connecting with GUI SDM Express Wizard with no CLI preconfiguration Resetting the router to factory defaults using SDM Configuring interfaces using SDM Configuring routing using SDM Using SDM to configure a router to act as a DHCP server Using SDM to configure an interface as a DHCP client Using SDM to configure NAT PAT What to do if you lose SDM...

Setting Duplex Operation

fastethernet 0 1 Moves to interface configuration mode 2960Switch(config) interface fastethernet 0 1 Displays current MAC address forwarding table Deletes all entries from current MAC address forwarding table switch clear mac address-table dynamic Deletes only dynamic entries from table 2960Switch(config) mac address-table static aaaa.aaaa.aaaa vlan 1 interface fastethernet 0 1 Sets a permanent address to port fastethernet 0 1 in VLAN 1 2960Switch(config) no mac address-table static aaaa....

Setting Passwords

Setting passwords for the 2960 series switches is the same method as used for a router. 2960Switch(config) enable password cisco 2960Switch(config) enable secret class Sets the encrypted secret password to class 2960Switch(config-line) password cisco 2960Switch(config-line) password cisco 2960Switch(config-line) line vty 0 4 Enters line vty mode for all five virtual ports 2960Switch(config-line) password cisco Setting IP Addresses and Default Gateways Enters the virtual interface for VLAN 1,...

Setting the Encapsulation Type

Depending on the series of switch that you are using, you might have a choice as to what type of VLAN encapsulation you want to use the Cisco proprietary Inter-Switch Link (ISL) or the IEEE Standard 802.1q (dotlq). The 2960 switch supports only dotlq trunking. 3560Switch(config) interface fastethernet 0 1 Moves to interface configuration mode 3560Switch(config-if) switchport mode trunk Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link...

Shortcuts in Binary ANDing

Remember when I said that this was supposed to save you time when working with IP addressing and subnetting Well, there are shortcuts when you AND two numbers together An octet of all 1s in the subnet mask will result in the answer being the same octet as in the IP address. An octet of all 0s in the subnet mask will result in the answer being all 0s in that octet. Question 4 To what network does 172.16.100.45 belong, if its subnet mask is 255.255.255.0 Step 1 Convert both the IP address and the...

So Why AND

The best answer is to save you time when working with IP addressing and subnetting. If you are given an IP address and its subnet, you can quickly find out what subnetwork the address belongs to. From here, you can determine what other addresses belong to the same subnet. Remember that if two addresses are in the same network or subnetwork, they are considered to be local to each other and can therefore communicate directly with each other. Addresses that are not in the same...

Step 1 Determine How Many H Bits Will Be Needed to Satisfy the Largest Network

A is the largest network with 50 hosts. Therefore, you need to know how many H bits will be needed If 2h - 2 Number of valid hosts per subnet Therefore H 6 (6 is the smallest valid value for H) You need 6 H bits to satisfy the requirements of Network A. If you need 6 H bits and you started with 8 N bits, you are left with 8 - 6 2 N bits to create subnets Started with NNNNNNNN (these are the 8 bits in the fourth octet) Now have NNHHHHHH All subnetting will now have to start at this reference...

Step 1 Summarize Winnipegs Routes

To do this, you need to look at the routes in binary to see if there are any specific bit patterns that you can use to your advantage. What you are looking for are common bits on the network side of the addresses. Because all of these networks are 24 networks, you want to see which of the first 24 bits are common to all four networks. 172.16.64.0 10101100.00010000.01000000.00000000 172.16.65.0 10101100.00010000.01000001.00000000 172.16.66.0 10101100.00010000.01000010.00000000 172.16.67.0...

Step 2 Pick a Subnet for the Largest Network to

You have 2 N bits to work with, leaving you with 2N or 22 or 4 subnets to work with NN 00HHHHHH (The Hs The 6 H bits you need for Network A) If you add all zeros to the H bits, you are left with the network numbers for the four subnets 00000000 .0 01000000 .64 10000000 .128 11000000 .192 All of these subnets will have the same subnet mask, just like in classful subnetting. Two borrowed H bits means a subnet mask of The x notation represents how to show different subnet masks when using VLSM. 8...

Step 3 Pick the Next Largest Network to Work With

Determine the number of H bits needed for this network You need 5 H bits to satisfy the requirements of Network B. You started with a pattern of 2 N bits and 6 H bits for Network A. You have to maintain that pattern. Pick one of the remaining 26 networks to work with Network B. For the purposes of this example, select the .128 26 network 10000000 But you need only 5 H bits, not 6. Therefore, you are left with 10N00000 10 represents the original pattern of subnetting. N represents the extra bit....

Step 3 Summarize Edmontons Routes

For Edmonton, you do the same thing that we did for Winnipeg and Calgary look for common bit patterns in the routes 172.16.72.0 172.16.73.0 172.16.74.0 10101100.00010000 01001010.00000000 172.16.75.0 10101100.00010000 01001011.00000000 172.16.76.0 172.16.77.0 172.16.78.0 172.16.79.0 Common For Edmonton, the first 21 bits are common. The summarized route is therefore Figure 3-2 shows what the network looks like, with Winnipeg, Calgary, and Edmonton sending their summarized routes to Vancouver....

Step 4 Pick the Third Largest Network to Work With

Networks C and Network D 12 hosts each Determine the number of H bits needed for these networks You need 4 H bits to satisfy the requirements of Network C and Network D. You started with a pattern of 2 N bits and 6 H bits for Network A. You have to maintain that pattern. You now have a choice as to where to put these networks. You could go to a different 26 network, or you could go to a 27 network and try to fit them into there. For the purposes of this example, select the other 27 network .160...

Step 4 Summarize Vancouvers Routes

Yes, you can summarize Vancouver's routes to Seattle. You continue in the same format as before. Take the routes that Winnipeg, Calgary, and Edmonton sent to Vancouver, and look for common bit patterns 172.16.64.0 172.16.68.0 172.16.72.0 Common Because there are 20 bits that are common, you can create one summary route for Vancouver to send to Seattle Vancouver has now told Seattle that in one line of a routing update, 16 different networks are being advertised. This is much more efficient than...

Step 5 Determine Network Numbers for Serial Links

All serial links between routers have the same property in that they only need two addresses in a network one for each router interface. Determine the number of H bits needed for these networks You need 2 H bits to satisfy the requirements of Networks E, F, G, and H. You have two of the original subnets left to work with. For the purposes of this example, select the .0 26 network 00000000 But you need only 2 H bits, not 6. Therefore, you are left with 00NNNN00 00 represents the original pattern...

Sticky MAC Addresses

Sticky MAC addresses are a feature of port security. Sticky MAC addresses limit switch port access to a specific MAC address that can be dynamically learned, as opposed to a network administrator manually associating a MAC address with a specific switch port. These addresses are stored in the running configuration file. If this file is saved, the sticky MAC addresses do not have to be relearned when the switch is rebooted, and thus provide a high level of switch port security. Switch(config)...

STP and Ether Channel

This chapter provides information and commands concerning the following topics Enabling Spanning Tree Protocol Configuring the root switch Configuring a secondary root switch Configuring the switch priority of a VLAN Optional STP configurations Changing the spanning-tree mode Enabling Rapid Spanning Tree Troubleshooting Spanning Tree Interface modes in EtherChannel Guidelines for configuring EtherChannel Configuring Layer 2 EtherChannel Configuration example EtherChannel

The ping and traceroute Commands

This chapter provides information and commands concerning the following topics Examples of using the ping and the extended ping commands Disables ICMP redirects from this specific interface Reenables ICMP redirects from this specific interface Checks for Layer 3 connectivity with device at address w.x.y.z Enters extended ping mode, which provides more options The following table describes the possible ping output characters. The following table describes the possible ping output characters....

Troubleshooting Spanning Tree

Displays all spanning-tree debugging events Displays spanning-tree debugging topology events Switch debug spanning-tree backbonefast Displays spanning-tree debugging BackboneFast events Switch debug spanning-tree uplinkfast Displays spanning-tree debugging UplinkFast event Switch debug spanning-tree switch state Displays spanning-tree port state changes

Using Global Configuration Mode

Changes the switch to VTP client mode. Changes the switch to VTP server mode. Changes the switch to VTP transparent mode. NOTE By default, all Catalyst switches are in server mode. Returns the switch to the default VTP server mode. Switch(config) vtp domain domain-name Configures the VTP domain name. The name can be from 1 to 32 characters long. NOTE All switches operating in VTP server or client mode must have the same domain name to ensure communication. Switch(config) vtp password password...

Using Sequence Numbers in Named ACLs

Router(config) ip access-list extended serveraccess2 Creates an extended named ACL called serveraccess2. Router(config-ext-nacl) 10 permit tcp any host 131.108.101.99 eq smtp Uses a sequence number 10 for this line. Router(config-ext-nacl) 20 permit udp any host 131.108.101.99 eq domain Sequence number 20 will be applied after line 10. Router(config-ext-nacl) 30 deny ip any any log Sequence number 30 will be applied after line 20. Returns to global configuration mode. Router(config) interface...

Using the range Command

Switch(config) interface range fastethernet 0 1 - 9 Enables you to set the same configuration parameters on multiple ports at the same time. NOTE There is a space before and after the hyphen in the interface range command. Switch(config-if-range) switchport mode access Switch(config-if-range) switchport access vlan 1O

Using VLAN Configuration Mode

Creates VLAN 3 and enters VLAN configuration mode for further definitions. Switch(config-vlan) name Engineering Assigns a name to the VLAN. The length of the name can be from 1 to 32 characters. Applies changes, increases the revision number by 1, and returns to global configuration mode. NOTE This method is the only way to configure extended-range VLANs (VLAN IDs from 100 to 4094). NOTE Regardless of the method used to create VLANs, the VTP revision number is increased by 1 each time a VLAN is...

Using VLAN Database Mode

CAUTION The VLAN database mode has been deprecated and will be removed in some future Cisco IOS Software release. It is recommended to use only VLAN configuration mode. Creates VLAN 4 and names it Sales. The length of the name can be from 1 to 32 characters. Creates VLAN 10 and gives it a name of VLAN0010 as a default. Applies changes to the VLAN database and increases the revision number by 1. Applies changes to the VLAN database, increases the revision number by 1, and exits VLAN database...

Using Wildcard Masks

When compared to an IP address, a wildcard mask identifies which addresses get matched to be applied to the permit or deny argument in an access control list (ACL) statement A 0 (zero) in a wildcard mask means to check the corresponding bit in the address for an exact match. A 1 (one) in a wildcard mask means to ignore the corresponding bit in the address can be either 1 or 0. 172.16.0.0 10101100.00010000.00000000.00000000 0.0.255.255 00000000.00000000.11111111.11111111 result...

Verifying and Troubleshooting IPv6

CAUTION Using the debug command may severely affect router performance and might even cause the router to reboot. Always exercise caution when using the debug command. Do not leave debug on. Use it long enough to gather needed information, and then disable debugging with the undebug all command. TIP Send your debug output to a syslog server to ensure you have a copy of it in case your router is overloaded and needs to reboot. Deletes routes from the IPv6 RIP routing table and, if installed,...

Verifying Ether Channel

Displays list of what is currently running on the device Switch show running-config interface fastethernet 0 12 Displays interface fastethernet 0 12 information Displays all EtherChannel information Switch show etherchannel 1 port-channel Displays a summary of EtherChannel information Clears PAgP channel group 1 information Clears LACP channel group 1 information

Verifying STP

Displays STP information on active interfaces only Displays a detailed summary of interface information Switch show spanning-tree interface gigabitethernet 0 1 Displays STP information for interface gigabitethernet 0 1 Switch show spanning-tree summary totals Displays the total lines of the STP section

Verifying VTP

Displays general information about VTP configuration Displays the VTP counters for the switch NOTE If trunking has been established before VTP is set up, VTP information is propagated throughout the switch fabric almost immediately. However, because VTP information is advertised only every 300 seconds (5 minutes), unless a change has been made to force an update, it can take several minutes for VTP information to be propagated.

VLAN Trunking Protocol and InterVLAN Routing

This chapter provides information and commands concerning the following topics Dynamic Trunking Protocol (DTP) Setting the encapsulation type VLAN Trunking Protocol (VTP) Using global configuration mode Inter-VLAN communication using an external router Router-on-a-stick Inter-VLAN communication tips Configuration example Inter-VLAN communication

Vlsm

Variable-length subnet masking (VLSM) is the more realistic way of subnetting a network to make for the most efficient use of all of the bits. Remember that when you perform classful (or what I sometimes call classical) subnetting, all subnets have the same number of hosts because they all use the same subnet mask. This leads to inefficiencies. For example, if you borrow 4 bits on a Class C network, you end up with 14 valid subnets of 14 valid hosts. A serial link to another router only needs 2...

VLSM Example

You follow the same steps in performing VLSM as you did when performing classical subnetting. Consider Figure 2-1 as you work through an example. Figure 2-1 Sample Network Needing a VLSM Address Plan A Class C network 192.168.100.0 24 is assigned. You need to create an IP plan for this network using VLSM. Once again, you cannot use the N bits 192.168.100. You can use only the H bits. Therefore, ignore the N bits, because they cannot change The steps to create an IP plan using VLSM for the...

Warning and Disclaimer

This book is designed to provide information about the Certified Cisco Networking Associate (CCNA) exam and the commands needed at this level of network administration. Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information is provided on an as is basis. The author, Cisco Press, and Cisco Systems, Inc. shall have neither liability nor responsibility to any person or entity with respect to any loss or damages...

Who Should Read This Book

This book is for those people preparing for the CCNA exam, whether through self-study, on-the-job training and practice, or even through study within the Cisco Networking Academy Program. There are also some handy hints and tips along the way to hopefully make life a bit easier for you in this endeavor. It is small enough that you will find it easy to carry around with you. Big, heavy textbooks might look impressive on your bookshelf in your office, but can you really carry them all around with...

Wireless Access Point Configuration Linksys 300N Access Point

NOTE The wireless access point (AP) used in this chapter is the Linksys Wireless-N Broadband Router. If you are using a different AP, the screen captures shown here may differ. It is important to use the most up-to-date firmware or drivers. This is especially true for the 300N AP because the 802.11n technology is still in draft stage. Therefore, check the AP manufacturer website for available updates. In the case of Linksys, its website for updates is http www.linksys.com download. Figure 15-1...

Sequence Number Tips

Sequence numbers start at 10 and increment by 10 for each line. If you forget to add a sequence number, the line is added to the end of the list. Sequence numbers are changed on a router reload to reflect the increment by 10 policy (tip 1). If your ACL has numbers 10, 20, 30, 32, 40, 50, and 60 in it, on reload these numbers become 10, 20, 30, 40, 50, 60, 70. Sequence numbers cannot be seen when using the Router show running-config or Router show startup-config command. To see sequence...

Verifying and Troubleshooting DHCP Configuration

Displays a list of all bindings created Displays the bindings for a specific DHCP client with an IP address of w.x.y.z Clears an automatic address binding from the DHCP server database Displays a list of all address conflicts recorded by the DHCP server Clears address conflict from the database Displays recent activity on the DHCP database Router show ip dhcp server statistics Displays a list of the number of messages sent and received by the DHCP server Router clear ip dhcp server statistics...