The following is a summary of each topic in the chapter and some questions for your reflection.
What Did I Learn in This Chapter? (35.6.1)
• Cisco Switches—A switch is used to connect devices on the same network. A router is used to connect multiple networks to each other. When selecting a switch for your LAN, choosing the appropriate number and type of ports is critical. Lower-cost switches may support only copper twisted-pair interface ports. Higher-priced switches may have fiber-optic connections. These are used to link the switch to other switches that may be located over long distances.
Similar to a switch port, Ethernet NICs operate at specific bandwidths such as 10/100 or 10/100/1000 Mbps. The actual bandwidth of the attached device will be the highest common bandwidth between the device NIC and the switch port. Networking devices come in both fixed and modular physical configurations. A managed switch that uses a Cisco operating system enables control over individual ports or over the switch as a whole. Cisco Catalyst 2960 Series Ethernet switches are suitable for small- and medium-sized networks.
• Switch Speeds and Forwarding Methods—Switches use one of the following forwarding methods for switching data between network ports: store-and-forward switching or cut-through switching. Two variants of cut-through switching are fast-forward and fragment-free. Two methods of memory buffering are port-based memory and shared memory. There are two types of duplex settings used for communications on an Ethernet network: full-duplex and half-duplex.
Autonegotiation is an optional function found on most Ethernet switches and NICs. It enables two devices to automatically negotiate the best speed and duplex capabilities. Full-duplex is chosen if both devices have the capability along with their highest common bandwidth. Most switch devices now support the automatic medium-dependent interface crossover (auto-MDIX) feature. When enabled, the switch automatically detects the type of cable attached to the port and configures the interfaces accordingly.
• Switch Boot Process—Cisco switches are preconfigured to operate in a LAN as soon as they are powered on. Configure the basic security settings before placing the switch into the network. The three basic steps for powering up a switch are as follows: (1) Check the components, (2) Connect the cables to the switch, and (3) Power up the switch. When the switch is on, the power-on self-test (POST) begins.
There are two methods to connect a PC to a network device to perform configuration and monitoring tasks: out-of-band management and in-band management. Out-of-band management requires a computer to be directly connected to the console port of the network device that is being configured. Use in-band management to monitor and make configuration changes to a network device over a network connection.
A Cisco device loads the following two files into RAM when it is booted: the IOS image file and the startup configuration file. The IOS image file is stored in flash memory. The startup configuration file is stored in NVRAM.
• Cisco Routers—Routers require an OS, a CPU, RAM, ROM, and NVRAM. Every Cisco router has the same general hardware components: console ports, LAN interfaces, expansion slots for different types of interface modules (e.g., EHWIC, Serial, DSL, switch ports, wireless), and storage slots for expanded capabilities (e.g., compact flash memory, USB ports).
• Router Boot Process—Follow these steps to power up a Cisco router:
Step 1. Securely mount the device to the rack.
Step 2. Ground the device.
Step 3. Connect the power cable.
Step 4. Connect a console cable.
Step 5. Turn on the router.
Step 6. Observe the startup messages on the PC within the terminal window as the router boots.
The most common methods to access the command-line interface on a Cisco router are console, SSH, and Aux ports. Routers also have network interfaces to receive and forward IP packets.
I found this chapter very helpful and I hope you did too. Now I want to go back to my office network and tour it again. Knowing how to set up multiple switches and routers will help me better understand why our network is set up the way it is.
Now that you know how to set up a multi-switch, multi-router network, see if you can tour your office or school network.
• What are the advantages of having the network set up the way it is?
• How might it change if the network were to double in size?