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: 3,240 Welcome to our Cisco IOS Classic Command Cheat Sheet! Cisco switches and routers use the Internetwork Operating System (IOS), which configures and controls the device’s performance and behavior. Cisco’s IOS defines an interface called the Command Line Interface (CLI), which enables administrators to enter commands into a terminal emulation program. The CLI […]
Cisco IOS Classic Command Cheat Sheet Read More »
Post Views: 1,485 We are always adding to, and updating the technical “how to’s” contained here. When it comes to configuring a new Cisco router, much of the configuration depends on what type of router it is as well as the purpose it will serve. However, there are certain things you should configure on every
Top 10 Cisco IOS Classic Commands Read More »
Post Views: 2,421 Many of our MPLS students and colleagues ask us about VRF Lite. The common question is “Can I use VRF Lite to simplify MPLS configuration?” The answer is, that VRF Lite actually has nothing to do with MPLS nor MPLS L3VPN per se. Let’s define what VRF Lite is. A VRF is
VRF Lite Configuration in Cisco IOS Read More »
Post Views: 3,134 As most of us know, a key to managing the Internet is knowledge of TCP and UDP port numbers. Cisco IOS uses Access Control Lists for many purposes, but in this tip, we will focus on TCP and UDP port numbers. Port numbers are unique, well-known, registered or ephemeral numbers used by
UDP and TCP Port Number Usage in ACL’s in Cisco IOS Read More »
Post Views: 1,474 Accessing the Internet is almost taken for granted today by most workers. They get very comfortable simply opening the lid to their laptop, turning on the wireless or connecting a cable and having access. For many of our clients, this notion of “open access” has been a continual challenge. On the one
Switch Port Security Usage in Cisco IOS Read More »
Post Views: 1,752 Network broadcasts can create a huge amount of traffic on your organization’s network. When one device sends out a single broadcast, that broadcast goes to all devices on the subnet or VLAN. How can you manage these broadcasts to make your network more efficient? One method is to use Cisco Catalyst broadcast
Storm Control for Switches in Cisco IOS Read More »
Post Views: 1,689 Welcome to our Cisco IOS Classic Interface Commands Cheat Sheet. You can see our other IOS cheat sheet here. You can view all our Cisco IOS How To’s here. Here are the most frequently used Interface commands as a quick reference/cheat sheet. This will help you remember the key interface configurations: Important
Cisco IOS Classic Interface Commands Cheat Sheet Read More »
Post Views: 2,210 The Show Environment command can be very helpful to alert you of potential hardware issues. You will need to access this command in global Exec mode. Here are the options available for the Show Environment command: show environment [alarms | all | fans | hardware | last | leds | power-supply |
Show Environment Command in Cisco IOS Read More »
Post Views: 2,415 The primary purpose of the show interfaces command is for displaying the equipped interfaces and their status. Here’s the information you can get about an interface from this command: Interface type Status Speed and duplex Encapsulation Errors on the interface The last time the interface flapped The last time the error counters
Show Interfaces Command in Cisco IOS Read More »
Post Views: 1,776 What happens if there is a system or user on a VLAN that is infected by malware or is deliberately running a scanning program? What if you have some public ports on your switches that you only want to have access to the Internet and not each other? This problem can be
Protected Ports on Cisco Switches in Cisco IOS Read More »
Post Views: 2,132 Point-to-Point (PPP) Protocol is an excelent Layer 2 protocol used to establish a direct connection between two nodes. It can provide connection authentication, transmission encryption (using ECP, RFC 1968), and compression. PPP was designed somewhat after the original HDLC specifications. The designers of PPP included many additional features that had been seen
PPP Configuration in Cisco IOS Read More »
Post Views: 1,575 What is Policy-based Routing? With policy-based routing (which we will call PBR from here on out), you get the option to implement policies that selectively cause packets to take different paths. Additionally, PBR can mark packets so that certain types of traffic get prioritized. One example of PBR is, say that your
Policy Based Routing feature Usage in Cisco IOS Read More »
Post Views: 2,148 This How To explains Passwords on Cisco platforms. The question you might ask is: Doesn’t the router already have default passwords? The answer is NO, it doesn’t. There is no automatic password defense that comes with your router. As a Cisco admin, this should be taken very seriously. It is so important
Passwords in Cisco IOS Read More »
Post Views: 2,250 OSPF (Open Shortest Path First) is an IGP (internal gateway protocol), and OSPF is an open standard protocol originally defined in RFC 2328. Since then OSPF has been updated numerous times including functionality to support IPv6 and Address Families. OSPF is supported on every major routing platform as well as Windows Server
OSPF Basics in Cisco IOS Read More »
Post Views: 1,458 If you want to partition flash memory of routers with flash, you can. On most class B Flash file systems, you can partition banks of Flash memory into separate, logical devices so that the router can hold and maintain two or more different software images. This partitioning allows you to write software
Partitioning Internal FLASH in Cisco IOS Read More »
