As common place in today’s networks redundancy is key. Applications are the key components to business obtaining revenue. More and more applications are becoming SaaS and ecommerce is here to stay. With that being said, many companies are moving to redundant connections to the internet. These connections could be through two different ISPs, or both connections to the same ISP. Often times these connections will be of different speeds to save on costs. The key to these connections is to maintain internet connectivity.
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Continuing with our OSPF and interior gateway protocols we will not look at an MD5 implementation utilizing OSPF on a Cisco router. We will again continue with our 3 router topology as used in both the EIGRP MD5 example and the OSPF plain text example. There are very few changes that will need to be made to our earlier OSPF example using plain text. The topology is as follows.
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Continuing with our interior routing protocol discussion on authentication we are going to look at Cisco OSPF implementation of plain text authentication. While this isn’t the most widely used model for authentation with OSPF it is a viable option. The topology we are going to use is the same topology from the EIGRP authentication example. The steps may feel familiar as well.
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The Scenario is this…Company A has purchased Company B. One is an enterprise of thousands of users, the other a mid size company in the multiple hundres. However, as would happen to be the case, both companies utilize an overlapping subnet. To further complicate the issue it has been decided that both companies need to terminate at Company A’s core and utilize a single unified instance of EIGRP. As part of this scenario, both companies need to be abble to access each others networks but luckily it has been determined that neither need to be able to access each others overlapped networks. Additionally both companies advertise different bit masks on their overlapping networks. This is something that we can work with.
The following examples show the additional configuration required for the specific scenario above. The full router configurations are posted at the end of the article.
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The scenario looks like this. You’ve got a branch office with a single router connecting to your corporate office over the WAN. In your branch office you have a single layer 2 switch and a desire to separate traffic into multiple broadcast domains. Maybe you want an easy way to allow only HR computers to connect to a very specific branch office server and the only place for any restriction of traffic is on that branch office router. Here is where your router on a stick comes into play.
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Cisco routers are capable of doing many more things than simply routing packets. In fact, it can operate as a small DHCP server when needed. By no means is it a replacement for your enterprise, centrally managed DHCP server but it does have its applicable scenarios. Lets say you have a branch office that has its own server for any particular reason. Maybe it is a local file share for an engineering departments CAD program and rather than having all file traffic from opens and saves traverse the WAN during the day, you simply run backs of that server across the WAN at night. Continue reading
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Routing is at the core of the network infrastructure. Routing is what ultimately lets you get from point A to point B not only in your own network, but also across the entirety of the world wide web. Routing in its simplest form tells your network devices the path to get to another network device located on another network. This was originally handled by creating static routes to the required destinations.
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Todays enterprise network is heavily focused on providing as near to 100% uptime as possible. Newer technologies such as virtualization and server clusters have been a focal point in achieving this level of service for some time now. However, an often missed opportunity to provide that level of service exists in the core of your infrastructure. Many medium size organizations will implement a server monitoring resource to measure and track the uptime on their core applications and infrastructure servers such as DHCP, DNS, SharePoint, Active Directory, and so on. Often times this monitoring server is located within the data center, and likely on the same subnets as the servers themselves. This can quickly skew your uptime numbers in the sense of “can my users reach the servers?”. While true, the uptime of the servers may be near 100% from the standpoint of the monitoring system, that does not indicate the ability for your users to reach the servers, or in the same concept, your servers to reach your users. Enter default gateway redundancy.
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In my chase for CCNP I came across virtual links while studying for the CCNP ROUTE exam. When I first read through the concept I was slightly lost during the description. However, upon a couple of runs through a lab it became clear on how easy the were. Before I list the condensed two step (or focus points if you will) to look at let’s look at what a virtual link is and why we would use it.
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I often get asked what the best way to study for an Information Technology certification is and what it entails. Throughout my career I have taken a number of certification and have developed a strategy that has been working for me with relatively good success for quite some time. While I understand that everyone has a diferrent learning style, and learns at a different pace, I believe many of the concepts can be adjusted to the individual. In fact, my process relies upon creating a timeline based on your own learning goals. In this article I am going to outline my certification preparation techniques and some of the tools I use to accomplish my training. Most of the tools I use are no-cost freeware and readily available on the internet. A quick google search should suffice in obtaining most of them.
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