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.
We welcome your feedback and suggestions. If you have questions about any of the content, ideas for additional topics, or requests for Cisco technologies and configurations not currently covered, please contact us using our Contact Us form. Your input helps us continue expanding and improving this resource for the networking community.
Thank you for visiting and supporting CellStream’s learning resources.
Post Views: 2,134 The order of operations is hard coded into Cisco IOS and tells the router how to process traffic according to the configuration of different router functions and features. While we cant’ make you think like a router, it is likely you have already picked up on some of these. When configuring features […]
Order of Operations in Cisco IOS Read More »
Post Views: 1,353 What is NBAR? NBAR is a powerful packet filtering/identification/firewall that you may already have installed on your Cisco router. For a list of what NBAR can detect look here. NBAR is also what we call Cisco’s “autopilot” for QoS. It has been in IOS since ver. 12.0 and has been continually updated
NBAR Explained in Cisco IOS Read More »
Post Views: 1,769 As we said in our basic ACL How To, ACL’s’ are vital to networking today. Everyone uses them, and proper usage is imperative. In this How To, we are going a little deeper into two ACL types: Intrastructure and Transit. We will discuss the two with examples and you will clearly understand
Access Control to Infrastructure (iACL) and Transit (tACL) Read More »
Post Views: 2,252 ACL’s’ are vital to networking today. Everyone uses them, and proper usage is imperative. Besides being difficult to use at times, the penalty for an ACL mistake is huge. In one swift swoop, you could incorrectly permit malicious attackers onto your network or incorrectly deny all valid users from your network. Either
Access Control List (ACL) Basics Read More »
Post Views: 1,440 What is AAA? It stands for Authentication, Authorization, and Accounting. When it comes to network security, AAA is one of many features a network manager may use. Here is what each of these are used for and why you should care: Why every network admin should care about AAA Besides passing certification
AAA Usage in IOS Classic Read More »
Post Views: 1,592 This How To explains how to fix an annoying default behavior on Cisco IOS. Mistype a command on a Cisco router and the router thinks you just typed a hostname. This is often an annoying problem. For example: Router#shwoTranslating “shwo”…domain server (10.1.1.1) % Unknown command or computer name, or unable to find
Stopping the Cisco Router from Trying to TELNET Read More »
Post Views: 1,466 This How To explains the fundamentals of configuring EIGRP. EIGRP is an advanced distance-vector routing protocol that is used on a computer network to help automate routing decisions and configuration. The protocol was designed by Cisco Systems as a proprietary protocol, available only on Cisco routers, but Cisco converted it to an
EIGRP Configuration in Cisco IOS Read More »
Post Views: 2,404 When a router has to forward a packet, it looks in its routing table to match as many bits as possible of the destination address to a route in its routing table. This is known as longest match routing. Once a match is found, the router forward the packet to the next
Administrative Distances in Cisco IOS Read More »
Post Views: 1,966 What happens if there is a system or user on a VLAN that is infected by malware or is deliberately running a scanning program? This can cause a massive amount of entries in the CAM Table of the switch. Think of the CAM table as the MAC address table. There is a
CAM Table Overflow Attack Mitigation on Cisco Switches Read More »
