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Routing & Switching

Cisco Routing & Switching

EEM, HSRP and BGP for HA and load balancing

This post describes how to use EEM to monitor BGP changes and trigger automatic configurations to remediate failures. Cisco IOS Embedded Event Manager (EEM) is a powerful and flexible subsystem that provides real-time network event detection and on-board automation.…

Cisco Routing & Switching

DHCP Relay and giaddr

In large networks, DHCP Servers are located on remote subnets, sometimes far from where the clients requesting the ip are located. In these cases, relays agents are needed to carry the DHCP Discover packets sourced from clients to the data center where the…

Cisco Routing & Switching

Setting Up a DHCP Server

Configuring a DHCP Server on a Cisco router is a very common task on SOHO enviroments. In small companies with a small number of hosts, there is no need of a separate DHCP Server, taking advantage of the DHCP Service avaliable…

Cisco Routing & Switching

EIGRP Summarization Issues

A common issue we can find when we doing summarization in EIGRP is the lost of the optimum path towards a remote network. This is due to the fact that EIGRP supress the most specific subnets, that is, those network…

Cisco Routing & Switching

High Availability using IP SLAs

Nowadays, with the arrival of converged networks where data, voice and video go through IP, the use of backup internet connections is mandatory for bussines continuity. Depending where we want to deploy this high availability, we have several options, if our company is large…

Routing & Switching

How to set up a terminal server on GNS3.

Sometimes, when the network topology involves many routers, managing all of them becomes a little bit annoying due to the huge number of windows terminals opened. Luckily, exists the terminal servers, that is, routers acting as a gateway between…

Cisco Routing & Switching

Filtering routes with RIP.

If our network is running RIP we have several options for route filtering. As always, we can play with various parameters in order to get the desired target: delete those unnecessary routes from the routing table. For this example…

Cisco Routing & Switching

Router as Frame Relay Switch

The first step before playing with the topology is setting up the router acting as frame relay switch, this is a very straight forward process, so I will show you how to do it in a few minutes. If you…

Cisco Routing & Switching

Base Topology

Because one of the main purposes of this blog is to present and explain network protocols, I decided to create a new topology as a base topology for the followings posts. Although I use the INE topology for my…