In this How To we will reveal how to bypass the system password on Cisco IOS routers.  This procedure is used regularly by CellStream consultants. As you will see, we are changing the configuration register to alter the boot process to exclude the configuration files that the router has, as within those configuration files is […]

Let’s say you’re implementing some changes on a router that has a large configuration file. Maybe something distracted you when you were making the change, but the new feature doesn’t work when you go to test it. You just want to back everything out and start from scratch. How can you do that? You have

In this How To we will reveal how to bypass the system password on Cisco IOS routers.  This procedure is used regularly by CellStream consultants. As you will see, we are changing the configuration register to alter the boot process to exclude the configuration files that the router has, as within those configuration files is

GLBP is a new protocol similar in function to HSRP (discussed here). It has been available since IOS version 12.2(14)S and you can read more at the Cisco site in this article on Gateway Load Balancing Protocol. GLBP and HSRP are both Cisco proprietary solutions, but VRRP is an open standard based on RFC 3768.

This How To explaing how to use Extended Ping and Extended Traceroute options in Cisco IOS. Extended Ping The ping command is just about as simple as it gets when it comes to troubleshooting. Ping is actually ICMP.  ICMP sends a encho request to a particular address and, if present, that device send back an

In this How To we will discuss the process for backing up and restoring configurations of your Cisco IOS devices. Whenever you have a good working configuration, it is always a good idea to create a backup – I like to call them “golden configurations”. This way, if you make changes that cause problems, you

This How To will explain the process to back up your IOS image.  Your IOS image is stored as a file in the non-volatile memory of your switch or router.  This image file is compressed to reduce its size and reduce the transfer times as much as possible. Before starting the procedure of IOS file

While RIP is not used for the ‘real’ Internet routing, and hasn’t been for many years, we often use RIP to do testing as it is so quick and easy to configure the protocol.  Also, if you are learning shortest path routing for the first time, RIP is a great place to start as it

This How To addresses the method of limiting bandwidth on ports of a Cisco Switch or Router. Why should you limit bandwidth? There are a number of reasons for limiting bandwidth on a Cisco switch Ethernet port. For example, let’s say you work for an Internet service provider in a colocation facility, and you sell

This How To covers something called Black Hole Routing using the NULL interface in Cisco IOS. The entire YouTube network went down in 2009, across the globe, for about two hours — thanks to a mistake made by an ISP in Pakistan. That mistake involved a black hole route accidentally distributed around the world. While

Generic Route Encapsulation is a tunneling technique in IP networking where a received IP packet is re-encapsulated in a second IP header (IP-in-IP) and sent across the network. It is like a Layer 3 VPN but alone it is not a secure VPN. You can encrypt GRE with an encryption protocol such as IPSec to

A common misunderstanding with configuring Cisco routers is the meaning of the ‘bandwidth’ command. Following a recent discussion we had with a client we thought it appropriate to add some specifics to our Tech Tips area. Let’s say you have a serial interface between two Cisco routers and the interface is up and running with

In this How To we will explain the basics of SSH configuration on Cisco IOS. To start, we recommend you verify you have the correct IOS version that supports triple-DES and SSH. With that said, let’s jump in. First, make sure your router has a hostname by using the hostname command. Here’s an example: Router#

In this How To we will introduce the concepts of Quality of Service or QoS (kwas). Managing QoS is an important process and skill that everyone who runs a network needs to understand.  We will introduce you to QoS principles at a high level. You will find details in other How To’s. First, lets understand