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Tag Archives: cisco
Parsing Cisco Show Command Output
If you have done even the basics in networking you have probably used a “show” command at some point on a Cisco networking device. Show commands give us insight into the configuration, performance and issues that face that device. One issue with show commands, however, is that they can be very verbose. Many commands give you way more information than you are looking for and are difficult to get through quickly. Luckily for you and I there are output modifiers to help us parse the output.
I will attempt to teach this short lesson with an example. Say you want to look at all interfaces and see what access lists are applied to them. You could do “show run” and read all of the output until you find what you are looking for.
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Discovering a Cisco Network with CDP (Part 3)
This is part 3 of the series on network discovery using CDP. If you have not read the first or second parts you can find them HERE and HERE. So far we have looked at mapping the infrastructure with CDP as well as actually mapping hosts (by MAC address) to switch ports. I wanted to take the opportunity, in this write up, to step away from the Cisco command line and look at another product that leverages CDP: VMware. As you already know CDP is simply a packet emitted from physical ports of Cisco devices. Anything that cares to listen … Continue reading
Discovering a Cisco Network with CDP (Part 2)
Part one of this two part series talked about walking out your network with CDP. This is useful when all you need to know is the topology of the network equipment its self. The next step in the process is to map out where servers or other hosts are located. The first way of doing this would be to log onto the host, capture packets, and look for a CDP packet that indicates the switch name and port that the host is connected to. This would require packet capture software on each system and is really not practical. The second … Continue reading
Discovering a Cisco Network with CDP (Part 1)
If you have ever been dropped face first into an undocumented Cisco network with little Cisco experience you may have found yourself overwhelmed. Fortunately for admins who have no desire to tone cables or read long mac address tables there is a simple way to map out a network like this. The Cisco Discovery Protocol (CDP) is the answer. There are a few prerequisites but overall the process is fairly simple. First, CDP must be enabled on all of the devices and ports you would like to discover. This typically is the case as CDP is enabled by default on … Continue reading
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