The OSPF (Open Short Path First) dynamic routing protocol is probably the most popular and most used IGP routing protocol in TCP/IP networks. Because OSPF is supported by all networking vendors, it does not have the restrictions of proprietary protocols like Cisco EIGRP for example (in terms of multi-vendor environments etc). The new Cisco CCNA […]
Readers Favorite Posts – Articles Liked by our Visitors
The following articles have been embraced by our readers because they offer valuable information about various networking topics: 1) Basic Cisco Router Configuration Step-By-Step This article discusses the 7 most important and most basic steps to follow for configuring any Cisco Router. Specifically, you will learn the following: Configure Access Passwords. Configure a Hostname. Configure […]
7 Types of Firewalls Technologies (Software/Hardware) Explained
The firewall is the cornerstone of security in computer networks and I.T in general. In this website I have been talking extensively about the Cisco ASA firewall which is a classic example of a hardware network firewall. However, there are some other types of firewalls used in large enterprises, SMB or even home networks. Some […]
12 Types of Network Devices Found in Modern Enterprise Networks
I’ve been working with small and large networks for almost two decades. I can say that I have pretty much seen it all. There are so many different types of network devices that you can write a whole book about. In this article I will describe briefly the most common network device types that you […]
Cisco ASA Firewall Packet Tracer for Network Troubleshooting
One of the most useful troubleshooting features of Cisco ASA firewalls is to use the “packet-tracer” command to trace and simulate how a packet will traverse through the ASA appliance in order to identify possible problems (such as why a packet is blocked etc). The packet tracing feature was introduced in Cisco ASA firewall version […]
8 Best Wired Routers for Home and Small Business Networks
In the market of networking devices, you can find both wireless routers (just like the WiFi devices we have in our homes) and wired routers which can be great performers in both small home networks and in business environments as well. In this article I have researched some great wired router models for both home […]
13 Best Open Source Router OS Software for Small or Large Networks
Usually, commercial and enterprise grade network routers (such as Cisco, Juniper, HPE etc) run on their own proprietary operating system (OS) software which runs only on the specific vendor’s hardware devices. However, the Open Source community has developed some great Router OS software that can power commodity hardware such as x86 computers or regular SOHO […]
VPN Failover with HSRP High Availability (Crypto Map Redundancy)
The purpose of HSRP (Hot Standby Routing Protocol) is to check interfaces and other connectivity parameters, and if the interface is down then a failover takes place from Active HSRP Router to standby HSRP router. There is no direct correlation between HSRP and IPSEC. However, we can use HSRP to provide VPN tunnel failover, as […]
Comparing Cisco IOS Configurations (Config Compare Tools)
In our day to day work as network administrators it is often necessary to compare configuration files of Cisco routers, switches, firewalls etc. As we know, a characteristic of Cisco IOS is that the configuration files are stored in text format, but still a line by line comparison of different config files is tedious and […]
How to Pass BGP Sessions through Cisco ASA Firewall (BGP Pass Through)
The following article describes the proper way to allow BGP sessions between two routers to pass through a Cisco ASA firewall appliance. Especially if the BGP configuration between the two routers uses MD5 authentication (which is a good security practice), you need some special “treatment” on this session in order to pass it successfully through […]
Traffic Rate and Bandwidth Limiting on Cisco ASA Firewall
With the new modular policy framework (MPF) introduced in ASA versions 7.x and 8.x, the firewall administrator is now able to apply policing and rate limiting to traffic passing through the ASA appliance. I got a few questions from people how this functionality works and decided to throw in a quick example below which you […]
Cisco ASA Virtual Firewall Configuration (with Config Example)
Device virtualization is one of the most popular topics in IT industry today and Cisco has been supporting this concept in the majority of its network devices. In this article we will talk about Cisco ASA virtualization, which means multiple virtual firewalls on the same physical ASA chassis. Virtual ASA is also known as “Security […]
Cisco ASA Firewall (5500 and 5500-X) Security Levels Explained
This article describes the security levels concept as used in the Cisco ASA firewall appliance. The following information applies to both the older 5500 series and the newer 5500-X series of appliances. What is Security Level A Security Level is assigned to interfaces (either physical or logical sub-interfaces) and it is basically a number from […]