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So now let's briefly change gears and talk about something known as EEM.

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Now what this stands for is Cisco's Embedded Events Manager.

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Now in essence EEM can be implemented in two different ways.

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We can have something known as an applet and we can also have EEM scripts.

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Now for our purposes the one we have to focus in on is the applets.

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Now the good news is is that this is the simpler implementation.

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Now basically what we're talking about here is when some type of event happens
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Now basically what we're talking about here is when some type of event happens

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on your system.

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You have this type of F style logic, this programmatic logic.

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If something happens, if an event happens then we want to perform a particular

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action in response.

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Now when we happen to create an EEM applet the actual response we specify is

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just well

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specified directly via the CLI whereas if we want to create an EEM script then

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we create

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something known as a TCL script. Again we don't have to focus on this so let's

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just stick with

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the applet via the CLI. So what type of thing could this be? Well let's maybe
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the applet via the CLI. So what type of thing could this be? Well let's maybe

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say we have,

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let's go with a router here and a router here, this can be R1, this can be R2.

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Let's suppose we happen to have some type of BGP peering across to this device

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here.

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So it's going to be BGP neighbour 2.2.2.2 and 1.1.1.1.

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Now say for example the connection here happens to flap and we get a syslog

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message on our device

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denoting and telling us that well our adjacency with 2.2.2.2 has ultimately

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went down with
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went down with

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loss that connection then in response perhaps we would like to issue the

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commands clear IP BGP

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soft which is simply a command we can use to reconfigure and activate BGP

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information within

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our devices. So again think about R1, R2. If we happen to have a problem with

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this neighbour

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relationship that happens to go down and respond to this happening before we

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even have to look at it

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or notice it or type anything in response to this particular action our EEA app

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let can be programmed
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let can be programmed

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to look for it and then respond accordingly by issuing this clear IP BGP soft

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commands.

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So we get that in sync kick in similarly let's maybe say someone happens to

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administratively shut

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down this link well what we could do is if we notice that link going down we

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can have an EEA

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applet to respond accordingly to that particular action and then bounce that

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interface back into

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the upstate. This is really all we're talking about here we're noticing events

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and in response

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to particular events we're going to be performing particular actions in this
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to particular events we're going to be performing particular actions in this

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nice automatic form.

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So let's go and see how this actually does operate there okay so what we'll do

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is go to the

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definite sandbox. So what I've done is log into a switch and what I'm going to

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do is I'm going

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to make configuration changes which will ultimately generate logs I will then

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use those logs as a

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pattern to match in order to invoke my EEA applets let me show you what I mean.

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Say for example I

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created a look back interface of look back let's go with 132 okay does it

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actually matter the name
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actually matter the name

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what we can actually see here straight away is the creation of that look back

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generated this

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message now if I happen to shut this down look at what we actually see here see

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this interface look

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back 132 is down say for example I just copy this right here okay now here's

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what I'm going to do

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for the moment let me just say no shut so it's back up in the upstate what I

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will do in fact what I

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will do is I will say interface look back 132 and let me just put an IP address

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of 192.168

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132.132 and give it a slash 32 mask okay and just say look back for IBGP pe
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132.132 and give it a slash 32 mask okay and just say look back for IBGP pe

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ering okay let's say

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this is the purpose of this particular look back okay so here's what I'm going

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to do as we can see

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if I go to show IP interface brief right now the protocol is in the upstate and

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as such what that

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means is that it can ultimately ping this address I can say do ping 192.168 132

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.132 as we can see

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right here now I will configure my EEM applets I'll say event manager applets
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right here now I will configure my EEM applets I'll say event manager applets

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that is the type

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we're going to be using and now I just give this applet a name let's just call

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this look back up okay

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now I'm inside the configuration what I will do is I will say event syslog

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pattern and then

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with think rotation marks I'm going to tell the system which pattern to look

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for so what I will

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do is I'll tell the system if you happen to see this particular pattern that

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look back 132 is down

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what I want to do is to perform a particular action so I'll say action and I'll
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what I want to do is to perform a particular action so I'll say action and I'll

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give this

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in the medical value this can be action 1.0 and I'll say it's a CLI command I

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want to be doing

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so now specify the command will be enable I'll then say the next command this

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will be

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command 1.2 this will be configure terminal it will be to go into that

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interface so I'll say interface

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look back 132 and then the next command will be action at 1.3 and that command

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will simply be

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to type no shutdown so if I just do end that is now configured that applet so

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here's what's going
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here's what's going

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to happen like I say right now if I do show IP interface brief we can see we

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are in the upstate

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for interface look back 132 now if I go into that look back right here and I

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happen to shut it down

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we're going to generate that logging message which is ultimately going to kick

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off these particular

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commands see how the interface is suddenly straight back up that is because

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this particular pattern

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set off the applet to go and kick off all of those commands I specified see the

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ones above enable

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configure terminal interface look back 1.3 and then the no shutdown command so
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configure terminal interface look back 1.3 and then the no shutdown command so

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if something happens to

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go in and you know erroneously pull down or look back that we're using for bgp

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then automatically

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pre-configured we're going to have EEM in order to save us