Imagine the following situation: You are a network engineer and your boss or a customer wants you to build a cheap and easy solution to host a publicly accessible server (such as Webserver, Email server, VPN server etc) using only a regular Cisco router. In most network designs, you will see that the usual and […]
Redistribution and OSFP – Discussion With Cisco Commands Examples
Redistribution in networks and in particular, in the context of IP routing, refers to the process of transferring or injecting routing information from one routing protocol or domain, into another. OSPF, as a routing protocol, can either be the protocol from which routes are redistributed, into which routes are redistributed, or both! In this article, […]
Cisco HSRP States and Troubleshooting (With Commands)
Hot Standby Router Protocol or HSRP is a Cisco proprietary first hop redundancy protocol that is used to configure default gateway redundancy. With HSRP (like other gateway redundancy protocols), two or more routers can achieve default gateway failover in the event that the primary gateway fails or becomes inaccessible. In this article, we will focus […]
Cisco Router Login – GUI Login and How to Secure Your Access
Many people ask how to connect and log in to a Cisco Router device. There are several methods to use such as access the web-based GUI of the Router using a browser, using a console connection (when you have direct physical access to the router), or using a network connection to login via SSH. In […]
Route Filtering and OSPF – Workaround With Distribute List Filtering
OSPF is one of the most popular routing protocols around. As a link state protocol however, when it comes to route filtering, it has some quirks that should be considered when deploying it. Unlike its distant cousins EIGRP and RIP, OSPF routes can only be filtered at the border of an OSPF area. In this […]
EIGRP Metric and K Values Explained
If you’ve used EIGRP at all, then you’ve probably already heard about its metric formula and the related K values that are used to measure the distance of a particular path to a destination network. It’s not always easy to get your head around these concepts and how they’re used in the context of this […]
EIGRP Variance and Unequal Cost Load Balancing in Networking
EIGRP is an advanced routing protocol that was originally developed by Cisco, but has since been adopted by other vendors as well. Along with OSPF, it is one of the most popular Interior Gateway Protocols (IGPs) used by large enterprises for the internal routing of their networks. One of the advantages that EIGRP has over […]
Comparison of Reported Distance vs Feasible Distance in EIGRP
One of the concepts involved with the EIGRP routing protocol that can sometimes be confusing is the idea of the feasible distance and the reported distance of a particular network destination. Understanding these two measurements of EIGRP is an important step in understanding some of the fundamental mechanisms of EIGRP. Definition of Terms Let’s start […]
Explanation and Comparison of OSPF E1 vs E2 Routes
Open Shortest Path First (OSPF) is a popular routing protocol used in many production networks throughout the world. Understanding route types is important when designing an OSPF topology for efficient and effective operation. Among the various route types OSPF offers, the External types E1 and E2 play an important role in importing routes from outside […]
Discussion and Explanation of OSPF Graceful Restart and Shutdown
OSPF is one of the most popular routing protocols for enterprise networks. It has been around since the 1980s and has been continually updated and revised to conform to the requirements of modern IP networks. As such, it is an extremely mature and robust routing protocol that can be tweaked and fine-tuned in many ways […]
Explanation and Configuration of OSPF MD5 Authentication on Cisco Networks
OSPF (Open Shortest Path First) is a dynamic routing protocol used in IP networks, primarily within large enterprise networks. In this article we will discuss and configure OSPF MD5 authentication on Cisco devices. Like other routing protocols, OSPF shares information about network topologies and prefixes between devices. This is done by exchanging messages between OSPF-enabled […]
Explanation of BGP Neighbor Adjacency States on Cisco Devices
Border Gateway Protocol (BGP) is the fundamental routing protocol that is used on the Internet. Like most routing protocols, BGP depends upon the creation of neighbor adjacencies between BGP routers to exchange prefixes and routing information. In order to successfully create these neighbor adjacencies, they go through a series of neighbor adjacency states. In this […]
How to Configure a Loopback Interface on Cisco Router & Switch
A loopback interface is a virtual interface that can be created within a network device and behaves much the same as a physical interface. Loopback interfaces can be configured on a Cisco router or a switch and have many uses. In this article, we’ll examine what they are, how they can be configured, and how […]