Upon completion of this chapter, you will be able to answer the following questions:
- What are Cisco LAN switches?
- What is the Cisco LAN switch boot process?
- What are Cisco small business routers?
- What is the Cisco router boot process?
Key Terms
There are no key terms for this chapter.
Introduction (17.0.1)
By now, you must be more than ready to test your knowledge and skills on a larger network. Larger networks require switches and routers. Switches and routers turn your LAN into part of a WAN, and your WAN into part of the World Wide Web, so you will want to know how to make them work. This chapter is the perfect starting point for you.
Cisco Switches (17.1)
Ethernet switches are Layer 2 devices that forward Ethernet frames. Switches can be interconnected to allow more devices to be connected.
Connect More Devices (17.1.1)
Home and small business networks usually do not require more than one or two networking devices to be able to function efficiently. A wireless router, equipped with wireless connections and a few wired connections, is the only piece of networking equipment that is necessary to provide sufficient connectivity for the average small group of users. These routers are configured through a web browser and have an easy-to-use graphical user interface (GUI) that guides you through the most common configuration items.
Wireless routers that are designed primarily for home use are not appropriate for most business networks that must support more than a few users. Modern networks use a variety of devices for connectivity. Each device has certain capabilities for controlling the flow of data across a network. A general rule is that the higher the device is in the OSI model, the more intelligent it is. This means that a higher-level device can better analyze the data traffic and forward it based on information not available at lower layers. As an example, a Layer 2 switch can filter the data and send it only out of the port that is connected to the destination, based on the MAC address.
As switches and routers evolve, the distinction between them may seem blurred. One simple distinction remains: LAN switches provide connectivity within the local-area networks of the organization, whereas routers interconnect local networks and are needed in a WAN environment. In other words, a switch is used to connect devices on the same network. A router is used to connect multiple networks to each other.
Figure 17-1 shows a series of Cisco switches.
Figure 17-1 Cisco Catalyst 9300 Series Switches
Figure 17-2 shows a series of Cisco routers.
Figure 17-2 Cisco 4300 Series Routers
In addition to switches and routers, other connectivity options are available for LANs. Wireless access points that are deployed in enterprises enable computers and other devices, such as smartphones, to wirelessly connect to the network, or share broadband connectivity. Firewalls guard against network threats and provide security, network control, and containment.
Cisco LAN Switches (17.1.2)
When a LAN grows to the point where the four Ethernet ports provided by the wireless router are not enough for all of the devices that need to attach to the wired network, it is time to add a LAN switch to the network. A switch can provide connectivity at the access layer of a network, connecting devices to a LAN. A switch can allow the network to grow without replacing central devices. When you‛re choosing a switch, there are a number of factors to consider, including the following:
- Type of port
- Speed required
- Expandability
- Manageability
Type of Port
When selecting a switch for your LAN, choosing the appropriate number and type of port is critical. Most lower-cost switches support only copper twisted-pair interface ports. Higher-priced switches may have fiber-optic connections. They are used to link the switch to other switches that may be located over long distances. The Cisco Catalyst 9300 series has a variety of options depending on your environment (see Figure 17-3).
Figure 17-3 The Cisco Catalyst 9300 Series
Speed Required
Ethernet twisted-pair interfaces on a switch have defined speeds. A 10/100 Ethernet port can function only at 10 megabits per second (Mbps) or at 100 Mbps. This means that even if the device that you are connecting to the 10/100 switch interface port is capable of connecting at gigabit speeds, the maximum speed at which it is able to communicate is 100 Mbps. Switches may also include gigabit Ethernet ports. If your Internet connection is more than 100 Mbps, a gigabit port is necessary to take advantage of the higher Internet bandwidth. Gigabit Ethernet ports also operate at 10/100 Mbps. Gigabit Ethernet is sometimes represented as 1000 Mbps. The Cisco Catalyst 9300 48S switch in Figure 17-4 has two 40 Gbps uplink ports to provide a fast path for the 48 ports to access the rest of the network and the Internet.
Figure 17-4 The Cisco Catalyst 9300 48S Switch
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 is the highest common bandwidth between the NIC on the device and the switch port.