Teaching how to use the COSI switches
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Using the TL-SG3424

This guide is in no way comprehensive - if you have more curiosities, you should read the manual in the manuals/TL-SG3424 folder.


  • Basic Operations
    • Log In
    • Overview
  • Managing VLAN Configurations
    • View VLAN configuration
    • Adding/Removing VLAN ID's
    • Adding VLAN ID's to a port
    • Set up a ACCESS port
    • Set up a TRUNK port
  • Managing LAG and LACP Configurations
  • Managing STP Configurations
    • View STP configuration
    • Change STP configuration
  • Saving Switch Config (!important!)
  • Notes on Backups

Basic Operations

Log in

To log into a network switch while in the lab, enter its IP address into your browser.

A current table of addresses:

Switch Name IP Address

For these examples, we will be logging into swm4.

Once you get to the login page, log in with the typical lab credentials for csguest.

login screen

Click Login.


This is what you see when you log in.


On the left are the menus that allow you to navigate to different parts of the configuration interface. On the top are the tabs that allow you configure that particular part of the configuration interface, and change the current view.

In this view, we can see what ports are connected. Ports 1 and 18 currently have gigabit connections. 100M connections and 10M connections will look different.

Below that, we have information about the system itself, as well as the configuration IP address and the system uptime, among other tidbits of information.

Managing VLAN Configurations

These instructions are for utilization of the VLAN configuration panel.

View VLAN configuration

If you click on VLAN, and then 802.1q VLAN, you will see the following:

vlan config overview

This view shows you what VLAN tags the switch knows about. By default, it only knows about "Default VLAN", and all of the ports will be in ACCESS mode on that VLAN.

If you click on the tab to the right of that, you will see the VLAN port config.

vlan port config overview

This view will show you much more detailed information about the ports themselves.

Adding and Removing VLAN ID's

To create a VLAN, on the VLAN config overview, click the "Create" button.

You will be greeted by the following screen:

add vlan screen

Next, select an unused VLAN ID, and enter it into the first box. In the second box, enter a description. Typcially, in COSI, these are in the following format:

v[vlan ID]_[purpose]

Some examples:

v2_cosi_priv (the private COSI network)
v3_cosi_pub (the public COSI network)

After that, click Apply below the port listing. Adding ports at this screen tends to (unintuitively) fail.

Adding VLAN ID's to a port

Depending upon whether your port in question is in ACCESS or TRUNK mode will change the behavior of this step.

In ACCESS mode, when you change the VLAN ID, it will replace any existing VLAN ID with the one you select.

In TRUNK mode, when you change the VLAN ID, it will add/remove the VLAN ID to a list of VLAN ID's that the port is allowed to access.

To add the port to a VLAN, go to the VLAN Config tab, and click Edit under the VLAN you want to add/remove the port from.

You will see the following configuration panel:

add or remove ports from vlan

Once you do that, select/unselect the ports you want to change (and remember the behavior as listed above).

Click "Apply" to finish and apply the changes.

Set up an ACCESS port

Click on the Port Config tab. You will see the following:

port config

To change to ACCESS, select the ports on the left that you want to change, then click ACCESS from the dropdown, and then click "Apply".

Do not try to change the PVID here. It will fail (inexplicably).

Set up a TRUNK port

Click on the Port Config tab. You will see the following:

port config

To change to TRUNK, select the ports on the left that you want to change, then click TRUNK from the dropdown, and then click "Apply".

Do not try to change the PVID here. It will fail (inexplicably).


If you get errors about the PVID when changing VLANs accessible on a TRUNK port, change it to a VLAN that will be on the TRUNK after the changes.

Managing LAG and LACP Configurations


Managing STP configurations

These instructions are for utilization of the STP configuration panel.

IMPORTANT NOTE: The OIT link we have will administratively go down automatically if it recieves ANY STP packets! DO NOT allow STP packets to touch OIT's network. You MUST disable STP for these interfaces!

Note: Some of these configs are probably broken in some ways, and need to be fixed in order to operate properly (example, topography of the network is not propogating the way it's supposed to).

View STP configuration

Click on the Spanning Tree menu on the left hand side. It looks like this:

stp overview

Edit STP Configuration

Most of the relevant edits to the switch configuration itself are made on the main STP Config page. You can select whether it's enabled or not, the version (we use STP), and some other parameters.

stp overview

The CIST Priority is probably the most important - the higher up the network you go, the higher the priority should be. For example, the root of our network is 0, M1 is 4096, and other switches are bigger numbers.

Per Port Configurations

If you click on the Port Config link in the left menu, you will be greeted with this.

stp port config

Most of the time, you only need to select the ports, and set the status to Enable or Disable, but sometimes you want to set the path costs and the priority of the link itself.

Saving Switch Config

To save the config, click on the "Save Config" option on the left menu. When you click it, it will ask you if you're sure and then save the config. This will take at least a few minutes.

save config

This step is important, since if the switch reboots, it will reset to this saved config, rather than any config you have without saving. This is important, because if you lock yourself out of the switch, it resets when you reboot it, so that you don't need to get to the console and reset the switch entirely and lose ALL of the configuration.

Notes on Backups

The best thing to do is NOT screw up the configuration or do a reset. The switch hardly stores any information about how it was configured in the "backup" file, so if you have a reboot, and you didn't save the config to the switch (as above), it can't be restored. Everything besides the root password will be forgotten. The "backup" and "restore" configuration is seriously lacking in any features (and puts out what looks to be an extremely minimal Cisco-style interface listing and config)