The Fundamentals of Cisco Switching and the Spanning Tree Protocol (STP)
In switching, decisions about which devices should be forwarded to which locations are made based on the devices’ physical addresses. The switching function is carried out by application specific integrated circuits, or ASICs, which are contained within switches. As a direct result of this, astonishingly quick switching speeds can be achieved. In today’s lesson, I will discuss how switches acquire the hardware addresses of hosts that are connected to them, as well as how they put this information to use in order to carry out their functions. I will concentrate on the protocol that was developed to eliminate the possibility of a broadcast loop existing.
I will describe the operation of the Spanning Tree Protocol (STP) in detail and use examples when necessary so that you can get a clear understanding of how it works. For those of you who are not familiar with this field, the Spanning Tree Protocol (STP) is what I am referring to.
Changing Over to Benefits
The hosts on a local area network (LAN) are connected to switches, which are very important networking devices. Switches terminate connections between hosts. They are made up of multiple Ethernet, Fast Ethernet, and Gigabit Ethernet interfaces, and their throughput rates are able to be adjusted.
They are analogous to highways that have multiple lanes and a number of exits for drivers to choose from. As a result of the fact that every host has its own dedicated lane on the highway, collision domains are segmented according to each individual switch port. There is no sharing of bandwidth, and an individual amount of independent, dedicated bandwidth is allocated to each host that is connected to each port. The following are the advantages of all of these:
Low level of delay
Lightning-Fast Prices at a Discount
Why are they so cheap? The solution to this problem is not complicated at all. Imagine you have a local area network that contains fifty hosts. Because every host requires access to the Internet, one of their requirements is to be connected to a router in some fashion. It is inefficient and wasteful for a router to have fifty different interfaces to terminate client connections.
By incorporating a switch into the network, the router is only required to have a single interface in order to connect to the switch. Additionally, the ASIC electronics of the switch are what allow all users to access the router’s exit point. A typical local area network connection is depicted in the diagram that follows.
The Function of a Switch
As was just mentioned, switches perform their functions at layer 2 of the OSI model, which is known as the data-link layer. They are simple devices that just need to be plugged in and turned on; there is no special configuration required to use them. When a brand-new switch is powered on for the first time, you can anticipate that it will work immediately out of the box. In a moment, we’ll investigate the specific steps involved in achieving this goal.
A layer 2 switch is responsible for the following three functions:
When a switch is powered on for the first time, it will “learn” the MAC addresses of any hosts that are attached to it. It will then save this information along with the interface port association in a table called the MAC table.
Forwarding—The switch is able to send frames out the appropriate interfaces by using the MAC address table as a guide.
Prevention of loops is supported by the presence of multiple connections between switches, which are there for redundancy purposes. However, if a sophisticated protocol is not used to prevent the formation of network loops, the multiple connections will likely result in the formation of such loops. Spanning Tree Protocol is the protocol that is running on the switch ports, and its purpose is to prevent data flooding as a result of loops while simultaneously maintaining redundancy.