Welcome to CellStream’s Cisco Router and IOS How-To Resource Center. This collection of articles, configuration examples, troubleshooting guides, and practical tutorials is designed to help network engineers, technicians, students, and IT professionals better understand, deploy, manage, and troubleshoot Cisco networking equipment.
Whether you’re learning the fundamentals of Cisco IOS, configuring routing protocols, implementing security features, troubleshooting connectivity issues, or preparing for certification exams, you’ll find practical, real-world guidance based on industry experience and proven best practices.
The content provided here is intended to help simplify complex networking concepts and provide actionable solutions you can apply in your own environment. As with any network configuration, always validate commands and procedures in a test environment before implementing changes in production networks.
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Post Views: 1,224 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 […]
Reload Procedure to Bypass System Password Read More »
Post Views: 1,391 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
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Post Views: 1,777 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
Reload Procedure to Bypass System Password in Cisco IOS Read More »
Post Views: 1,691 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
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Post Views: 2,589 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
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Post Views: 1,717 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
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Post Views: 1,328 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
Post Views: 1,582 In our high level overview of QoS we stated that configuring QoS can be complicated. Cisco developed NBAR as the QoS ‘autopilot’ as one solution to this problem. More recently, Cisco has developed something called AutoQoS, which also configures QoS settings for you. You can use AutoQoS to a)create policies based on
Post Views: 1,769 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
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Post Views: 2,166 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,
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Post Views: 2,087 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
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Post Views: 1,752 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
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Post Views: 2,411 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
Post Views: 2,239 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
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Post Views: 1,596 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.
QoS Fundamentals in Cisco IOS Read More »
