The “Ending” of Layer Two Redundancy

Although layer two redundancy should never end, this is the final chapter of understanding layer two redundancy in the network. Last week I talked about how and why STP (IEEE 802.1D) is important in the network and the problems and causes of not having it which can turn your network against you and everybody on it. Today’s post will talk about how a switch decides which one is in charge on the network and which ones aren’t Continue reading

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Link-State Protocols

Weeks ago and maybe months :), I talked about distance vector protocols and with that you probably got the feeling that when using a distance vector protocol it does not give a full network graphical representation of the entire network. Only the directly connected routes can’t remember? Check out this post Distance Vector Routing. Link state protocols are faster to converge network changes compared to distance vector however when compared to distance vector setup they can be harder to set up, maintain, and troubleshoot when problems arise. Continue reading

The Beginnings of Layer Two Redundancy

In a perfect world we would never need redundancy on a network infrastructure, but as you know as well as I know we don’t live in a perfect world. Hardware will eventually fail, bottlenecks will appear, and the speed of our network will become slower when we max the bandwidth on links. So having redundancy in routers, connections, and having a hierarchy network is one of best choices to make when improving the efficiently of the network. But in the OSI model there is one layer that can’t have redundancy at least logically and that is Layer two of the OSI model. Continue reading

Cisco Discovery Protocol

In today’s post let’s talk about CDP the Cisco Discovery Protocol. This protocol helps us in two ways, it first helps us verify that a connection between router or switch is set up correctly  at least up to layer two in the OSI model. This also helps us discover Cisco devices that are in are network and which interfaces these devices are connected too and from are Cisco equipment. The Cisco discovery protocol is Cisco proprietary  and before I go any further let me mention that CDP is a security risk because of the detailed information CDP gives out which helps you has a network administrator build a current network infrastructure, this can also hurt you because this information can easily be sniffed by programs that are easily searched on the internet. Continue reading

Cisco IOS Commands

This is the master list of some of the many Cisco IOS Commands that go with the CCNA track. This list also talks about what each command does in brief detail. You may also find that some commands may or may not be used for a CCNA level but offer some important information. If you don’t know what a command does or understand it, I would look at Cisco documentation. Continue reading