Introduction to CDP (Cisco Discovery Protocol)

(Rene Molenaar) #1

This topic is to discuss the following lesson:

(Gabriel S) #2


It’s always so good read your articles! I can understand them and make me feeling smarter :smiley: Thanks!!!


(Rene Molenaar) #3

Good to hear you like them Gabriel! :slight_smile:

(Hussein Samir) #4

Hi Rene,

I work as technical support in Internet Services & Communications company and we don’t use Cisco products only, we also use other network products from different vendors like Ubiquiti, mikrotik, Exalt, etc. and we connect all these different products with each other!!
so when I use CDP to show which devices connected to cisco switch or router I noticed that information of different vendors products also appears to me!!
My question is why I show this info ? I know that CDP is Cisco proprietary so how it’s able to identify the products from other vendors???

(Rene Molenaar) #5

Hi Hussein,

Some other vendors also support(ed) CDP. Some older HP procurve switches also had it.

I think Ubiquiti and Mikrotik also have some support for it. Nowadays we also use LLDP, it is similar to CDP:


(christopher c) #6


Cisco ASA doesn’t seem to have CDP available. Is it maybe configured a different way?


(Rene Molenaar) #7

Hi Chris,

The ASA doesn’t support CDP…not sure why but it doesn’t :slight_smile:


(Trust_the P) #8

Hello @ReneMolenaar ,

I work with Cisco ASRs devices running cisco XR OS, and they don’t have CDP enabled by default. You have to enable it globally withcdp run command and that’s not enough to make it work. You still have to enable it per interface as well with cdp enable command.


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(Trust_the P) #9


ASAs don’t have CDP feature and it make sense since they are firewall devices. :slight_smile: but there is a trick way to do this, I will lab it and show you the commands.

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(Lazaros Agapides) #10

Hello sales2161

Thanks for sharing that information. It’s important because it shows how much detail Cisco goes into in choosing what features are enabled by default and which are not. ASRs are used in larger enterprise networks, and as such may be susceptible to security issues. Because CDP can open doors to attacks, it is disabled by default to improve security, but as you mention, can be enabled by administrators only if required and only on interfaces where it is needed.

Thanks for sharing!