Module Practice and Quiz

What did I learn in this module?

Configure a Switch with Initial Settings

After a Cisco switch is powered on, it goes through a five-step boot sequence. The BOOT environment variable is set using the boot system global configuration mode command. The IOS is located in a distinct folder and the folder path is specified. Use the switch LEDs to monitor switch activity and performance: SYST, RPS, STAT, DUPLX, SPEED, and PoE. The boot loader provides access into the switch if the operating system cannot be used because of missing or damaged system files. The boot loader has a command line that provides access to the files stored in flash memory. To prepare a switch for remote management access, the switch must be configured with an IP address and a subnet mask. To manage the switch from a remote network, the switch must be configured with a default gateway. To configure the switch SVI, you must first configure the management interface, then configure the default gateway, and finally, verify your configuration.

Configure Switch Ports

Full-duplex communication increases effective bandwidth by allowing both ends of a connection to transmit and receive data simultaneously. Half-duplex communication is unidirectional. Switch ports can be manually configured with specific duplex and speed settings. Use autonegotiation when the speed and duplex settings of the device connecting to the port are unknown or may change. When auto-MDIX is enabled, the interface automatically detects the required cable connection type (straight-through or crossover) and configures the connection appropriately. There are several show commands to use when verifying switch configurations. Use the show running-config command and the show interfaces command to verify a switch port configuration. The output from the show interfaces command is also useful for detecting common network access layer issues because it displays the line and data link protocol status. The reported input errors from the show interfaces command include: runt frames, giants, CRC errors, along with collisions and late collisions. Use show interfaces to determine if your network has no connection or a bad connection between a switch and another device.

Secure Remote Access

Telnet (using TCP port 23) is an older protocol that uses unsecure plaintext transmission of both the login authentication (username and password) and the data transmitted between the communicating devices. SSH (using TCP port 22) is a secure protocol that provides an encrypted management connection to a remote device. SSH provides security for remote connections by providing strong encryption when a device is authenticated (username and password) and also for the transmitted data between the communicating devices. Use the show version command on the switch to see which IOS the switch is currently running. An IOS filename that includes the combination “k9” supports cryptographic features and capabilities. To configure SSH you must verify that the switch supports it, configure the IP domain, generate RSA key pairs, configure use authentication, configure the VTY lines, and enable SSH version 2. To verify that SSH is operational, use the show ip ssh command to display the version and configuration data for SSH on the device.

Basic Router Configuration

The following initial configuration tasks should always be performed: name the device to distinguish it from other routers and configure passwords, configure a banner to provide legal notification of unauthorized access, and save the changes on a router. One distinguishing feature between switches and routers is the type of interfaces supported by each. For example, Layer 2 switches support LANs and, therefore, have multiple FastEthernet or Gigabit Ethernet ports. The dual stack topology is used to demonstrate the configuration of router IPv4 and IPv6 interfaces. Routers support LANs and WANs and can interconnect different types of networks; therefore, they support many types of interfaces. For example, G2 ISRs have one or two integrated Gigabit Ethernet interfaces and High-Speed WAN Interface Card (HWIC) slots to accommodate other types of network interfaces, including serial, DSL, and cable interfaces. The IPv4 loopback interface is a logical interface that is internal to the router. It is not assigned to a physical port and can never be connected to any other device.

Verify Directly Connected Networks

Use the following commands to quickly identify the status of an interface: show ip interface brief and show ipv6 interface brief to see summary all interfaces (IPv4 and IPv6 addresses and operational status), show running-config interface interface-id to see the commands applied to a specified interface, and show ip route and show ipv6 route to see the contents of the IPv4 or IPv6 routing table stored in RAM. The output of the show ip interface brief and show ipv6 interface brief commands can be used to quickly reveal the status of all interfaces on the router. The show ipv6 interface gigabitethernet 0/0/0 command displays the interface status and all of the IPv6 addresses belonging to the interface. Along with the link local address and global unicast address, the output includes the multicast addresses assigned to the interface. The output of the show running-config interface command displays the current commands applied to a specified interface. The show interfaces command displays interface information and packet flow count for all interfaces on the device. Verify interface configuration using the show ip interface and show ipv6 interface commands, which display the IPv4 and IPv6 related information for all interfaces on a router. Verify routes using the show ip route and show ipv6 route commands. Filter show command output using the pipe (|) character. Use filter expressions: section, include, exclude, and begin. By default, command history is enabled, and the system captures the last 10 command lines in its history buffer. Use the show history privileged EXEC command to display the contents of the buffer.

1.6.4 Module Quiz – Basic Device Configuration