Cisco switch tutorials

Cisco switch: 802.1q trunk to router, aka router-on-a-stick

contributed by Al Banks on November 17, 2006 under Cisco switch

Connect a Cisco switch and router via 802.1q trunking. This configuration is known as a router-on-a-stick.

 

Disable or turn off CDP on Cisco switches

contributed by CISSP06 on August 12, 2006 under Cisco switch

Cisco Discover Protocol or CDP is a Cisco-proprietary protocol that runs on all Cisco products. CDP allows devices to learn about neighboring devices (the ones attached directly to the switch) including information about their platform, IP address, the version of IOS or other OS, VLAN membership, etc. This can be helpful information when troubleshooting network issues, it can also provide an attacker valuable information about the layout of your network. Other vulnerabilities include a denial of service attack in which CDP packets are generated, flooding the network. If you want to know how to turn off CDP, read on.

 

Cisco 2950 Switch: Create a VLAN

contributed by CISSP06 on July 28, 2006 under Cisco switch

The commands for creating a VLAN vary from one switch model to another. VLANs in a 2950 switch are configured in a manner similar to configuring an interface. This configuration is substantially different than a 2900 switch.

 

Cisco 2900 Switch: Create a VLAN

contributed by CISSP06 on under Cisco switch

A VLAN (Virtual Local Area Network) makes a single physical switch behave like several separate switches. A host connected to one VLAN cannot communicate through the switch to a host connected to another (although a router can permit communication between VLANs if desired). Here’s how to configure a new VLAN on a 2900 switch.

 

Cisco Switch 2900/2950: Display VLAN information

contributed by CISSP06 on under Cisco switch

Knowing the commands to display configuration information about Virtual LANs (VLANs) is as important as knowing the commands to configure them. The commands here display information about all VLANs or a single VLAN by number or name.

 

Cisco 2950 switch password recovery

contributed by BWAYCCTY on June 19, 2006 under Cisco switch

This documents the procedure for performing a password recovery on a Cisco 2950 switch (and probably other models, as well).

 

RSPAN using CatOS

contributed by jotfco on May 10, 2005 under Cisco switch

This small guide can be useful if you need to configure the RSPAN session on your Catalyst 6500.In this example we will see how to monitor more than one VLan using the RSPAN vlan. RSPAN has all the features of SPAN plus support for source ports and destination ports distributed across multiple switches, allowing remote monitoring of multiple switches across your network.The traffic for each RSPAN session is carried over a user-specified RSPAN VLAN that is dedicated for that RSPAN session in all participating switches. The SPAN traffic from the sources, which cannot be in the RSPAN VLAN, is switched to the RSPAN VLAN and then forwarded to destination ports configured in the RSPAN VLAN. The traffic type for sources (ingress, egress, or both) in an RSPAN session can be different in different source switches, but is the same for all sources in each source switch for each RSPAN session. Do not configure any ports in an RSPAN VLAN except those selected to carry RSPAN traffic. Learning is disabled on the RSPAN VLAN.

 

How to Determine Which Switch and Port You are Connected To

contributed by Caveman on May 4, 2005 under Cisco switch

Sometimes you need to know which switch and port you are connected to. I work for a community college with hundreds of switches. Here is a method I’ve found to work well.