the next topic of discussion is a very sharp topic, and it deals with Cisco Discovery Protocol.
Cisco Discovery Protocol is a layer to protocol that is used to map out your network.
Now the words map out. Your network should set. Send warning bells in your head because insecure environments
you should not allow people to map out your network. So this protocol should be turned off
if you are in a secure environment, which
most of the time happens In the DC Washington metro area,
CDP works between devices.
It is Cisco proprietary and on by default.
So if I go on rather one
and CDP is on by default
and if I say execute the command
I see if physically you see look at art apology. You see a router two or one
is connected to a router. One
on router to one serial 0102 rather one serial 000
So if I go into outer one and execute the show CDP neighbor command or neighbors command,
I see the device i d of the device at the other end, which is rather one
my local interfere serial 010
is connected to serial 000 off router one.
So my router to one serial 010 is connected to serial 000 on router one.
The platform on Router one is a C 2800 series router.
If I execute the command Sure. CDP neighbor detail, neighbors detail.
I see a little bit more detail about Router one.
Router one is running version 12.4
sub release 15 T operating system.
My interface serial 010
The platform ISS see 2800 series router
and I also see rowdier ones I p. Address, which is 200. 202 100.1
to show you that router ones I p address on serial 000 is actually 202 102 101.
I can go into Router One and execute the
you shou ID be inter fees,
brief command. And as you see, serial 000 on Router one. Has I p 201 11
now a variation of the show
CDP neighbors detail command because this one sure, you detailed information about all the devices you are connected to.
So if I execute this command on router one, it won't be as clean or if I execute this command. Yes, on router one.
Sure CDP neighbors detail.
I see detail about switch one
so router ones interface faceted at 00 is connected to switch ones. Fast. Ethan at Zito's Last 24
and the switch is a 35 60. Switch running
operating system version. $12 to sub release. 37 s e.
And I see information about rotter to a one, which is connected on the other side. On serial 000 router to one's address is 202 102 102
router ones into face 0000 is connected to
router to one's interface. Hero 010 and router to one is a C 2800.
See 2800 studies router
Now what if I just wanted to see you out? Or to a one? Variations of the shore CDB neighbor detail command is show CDP entry
are to a one are to a one being are two router to a one's host name
and hit enter. Then it would show me information Just about our to a one
and set off all my neighbors.
Another variation of the shore CDP neighbor detail Command is sure CDP
show CDP Entry star which stands for Show all my entries once again similar to the show CDP Neighbor Detail command, you see switch one and router to a one, which is on the cereal and over our one
again. It showed me information about which one
Which one is connected to our one on fast Internet 00 locally and
fast. Lieutenant zero slash 24 on the switch in
and our two alone disconnected
on our one to our two ones as 010
Now, as I said, you should turn off CDP if you are in a secure environment so I could go to interferes. Fascinating that 00 and say no
enable. That turns off CDP on my fastest in at 00 interface which is connected to switch one. Now if I ask for
let's clear the CDP table for us
with this Claire CDB table command. Now, if I look at show cdp
I don't see anything because CDP has not talked back and forth yet.
Let me bounce the interfaces.
Let me just reload this router real quick to hasten the process. I saved my work with the W R Command and reloaded the router.
You would not do this at work. I'm just trying to hasten the process of the lab
show CDP neighbor detail
That seems to have turned off CDP on all the interfaces.
Okay, we will go back a little bit.
No, we can keep rolling.
So as I said that in a secure environment, CDP should be turned off
go into an interface and say
no CDP unable to turn our CDP per interface.
Or you could say no CDP run
from config motew globally turnoff CDP on that device.
Now, if execute the command show CDP neighbor,
I hear or I get a message saying CDP is not enabled.
This concludes our CDP lecture