Switch

The main task of a switch is to unite devices into a single network. It transmits data received on one of its interfaces to another based on the source and destination MAC address information contained in the transmitted frame.

Their logic is based on the Switching Table. As soon as a new host appears on the network and tries to transmit any information, the switch records that a new MAC address has appeared on one of its interfaces. A switch records this data in the form of a table like this:

 

Interface X - MAC address Y

Cisco Systems' advertising announcements will tell you about the latest 21st-century technologies in the all-new Cisco Catalyst 9200 series of switches, which is positioned to create LANs for small and medium-sized offices.

Everything new and technological is always liked by IT directors and other management personnel, but not by network engineers and IT administrators. But do not be afraid this time, because the new bright design and improved features essentially hides the updated, but good old Cisco 2960 switch, used everywhere, loved by network engineers for its ease of setup, convenience and reliability.

Cisco Catalyst 9200 Switch Overview and Configuration Configure Cisco Catalyst 9200

Configuring a Cisco Catalyst 9200 switch is almost exactly the same as configuring a Cisco Catalyst 2960 switch, with the exception of a few new features that will not be required by most companies.

You can safely use the following articles to configure the Cisco Catalyst 9200 as a switch for connecting users, printers, and other LAN resources. The differences will only be in the configuration of the interfaces, since the Cisco 9200 has at least 1G.

The etherchannel (also called port channel sometimes) technology allows to combine several physical switch ports (from 2 to 8 total) into one logical port. This technology is often used to increase reliability of a connection between two devices. Traffic uses all active ports and, in case one physical port fails, this will have no effect on the overall availability of the connection. Naturally, the connection bandwidth is increased, as well.

For this example, we will look at configuring two Cisco switches. Let it be Cisco Catalyst 3560, although the technology and command syntax are universal and practically identical for all models.

On the first switch, SW-DELTACONFIG-1, we need to create a logical interface port-channel with a unique sequence number (for example, 1)

Let's consider a scenario in which there are two several departments of the same company that have to be connected using logically separate networks (VLANs) and need to communicate with each other, while being connected on a single Layer 3 switch Cisco 3560.
The task is to organize the following subnets (VLANs):

Step 0. Clear previous configuration

(This step should be performed only on new or test equipment, since it completely removes all existing configuration)
After you take your new switch out of the box, connect to it with a console cable and clear the factory configuration by entering the privileged mode and using the "write erase" command (you can learn more about Cisco IOS configuration modes in this article)

After this your switch will reboot, taking about three minutes to do so, and display a request for basic configuration wizard afterwards. You should decline:

Step 1. Hostname

Let's call our switch SWR-DELTACONFIG-1 (SWR is an abbreviation from SWitch Router). To do this, enter the configuration mode (conf t) and type the following commands:

In everyday work, it's often necessary to determine the switch and port a user or device is connected to. To do it, you don't have to look for it visually. All you need is to know its MAC address.
The point is that each switch stores information about all MAC addresses that showed at least any network activity in the last few minutes. Your task is to use this information wisely.
So, let's say you need to find the switch port a user John is connected to. It's known that the IP address of his computer is 192.168.10.100

There are two possible ways of how you can determine the MAC address:

Or

Let's consider the simplest case when you have to hook up 3 departments of a company to different logical networks (Vlans) using one access layer switch Cisco 2960 (Sometimes they are called switches of the second layer of OSI model).

For example we need to organize these networks (Vlan):

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