Cisco IOS Embedded Event Manager (EEM)

Hello All,

Is there a show command to list all the built-in EEM environment variables, eg. $_cli_result, etc.

Thanks.

Hello Isaac

Take a look at this Cisco command reference:

This command will display the name and value of the EEM environment variables. You can also take a look at this reference for a list of EEM built in environment variables:

I hope this has been helpful!

Laz

Hi,

I’m trying to write a EEM applet atm which will do the following;

  1. copy run file’x’
  2. auto confirm device prompting for ‘Confirm’
  3. reload
  4. auto confirm device prompting for ‘Confirm’

At the moment I’ve made an ‘alias’ for step 1, and I’m having trouble with how to auto confirm when the device prompts for input.

Cheers,
Rob

Hello Robert

Before writing up an EEM script is always a good idea to go over the manual implementation of what you want to do. In order to copy the running-config to another file name and reload the device, you must do the following:

R2#copy running-config flash0: 
Destination filename [running-config]? test.cfg
2949 bytes copied in 2.445 secs (1206 bytes/sec)

R2#reload
Proceed with reload? [confirm]

In my example above, I copied the running configuration to a file called test.cfg. So in this case, you would have to issue the first command, then wait for the proper prompt to appear and then put in the correct command. (There is no confirmation there).

In the case of the reload, you will have to wait for the confirm prompt to appear and then press Enter.

The EEM script would go something like this:

action 010 cli command "copy run flash0:" pattern "running-config"
action 020 cli command "test.cfg" pattern "copied"
action 030 cli command "reload" pattern "confirm"
action 040 cli command ""

After action 10, it confirms “running-config” appears in the prompt before moving to the next command. Similarly, in action 20, “copied” must appear. In 030 “reload” must appear. Finally, after all patterns are matched, the “” indicates that the Enter key should be applied.

It is the pattern keyword that does the matching. Note that I have not tested the above, and you should confirm that it functions before proceeding.

I hope this has been helpful!

Laz

Hi Laz,

Thanks for that, will have a play with this in my lab and report back!

One thing on this, with action 020, are we able to build a file name based on say device hostname + fixed string label, ie device-name + base.cfg ?

Cheers,
Rob

Hello Robert

It is possible to retrieve information such as the hostname of the device. There are many predefined functions that do these types of functions. Specifically, for what you’re looking for you need to use the following command:

action 01 info type routername

This command will store the hostname of the device in a predefined variable called $_info_routername. You can then call this variable in subsequent actions like so:

action 02 cli command "$_info_routername-base.cfg"

This command will concatenate the saved hostname with the -base.cfg suffix.

Many more such built-in variables can be found at this Cisco community post:

Unfortunately, I found that Cisco documentation is either inadequate or non-existent (or at least very hard to find!) when it comes to details about EEM features.

I hope this has been helpful!

Laz

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Thanks for that Laz, I had a quick glance at that link before but maybe I should have tried the find feature! I will try to post my draft EEM applet once its closer to the task of me semi-automating my lab! Cheers, Rob

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Actually, this command below works alot better than an EEM script imo (as I don’t have to wait for reload the device to load a file)

configure replace flash:router-backup-1 list

From this networklessons article of course! :slight_smile:

now back to labbing!

Cheers,

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Hello Robert

Great, thanks for sharing that… It’s posts like this that increase the value and usefulness of the forum, as users share their personal experience on what works best for them. Your contributions are much appreciated!

Laz

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Happy to help, hopefully will be able to contribute with more tips and tricks! Cheers,

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HI Laz,
thanks a lot for your explanation.
I’ve got a question about the time variable.

In my case i would like to copy the cfg to an tftp server but i need to have also the hostname and the time.

event manager applet TFTP-SAVE
 event cli pattern "(write|write memory|copy running-config startup-config)"  sync no skip no
 action 0.0 syslog msg "salvaggio-TFTP"
 action 1.0 cli command "enable"
 action 2.0 info type routername
action 3.0 cli command "copy running-config tftp://<tftp-server>/2021_$_info_routername.$_event_pub_sec.cfg"

WIth this configuration i will have hostname and seconds output but i need the date instead

copied cfg

  • 2021_test.1632471991.cfg

i’ve already tried with

action 3.0 cli command "copy running-config tftp://<tftp-server>/2021_$_info_routername.$_event_pub_time.cfg"

but the debug looks like that:

*Sep 24 11:01:46: %HA_EM-6-LOG: TFTP-SAVE : DEBUG(cli_lib) : : OUT : copy running-config tftp://<tftp-server>/2021_test.Sep 24 09:01:46.009.cfg
*Sep 24 11:01:46: %HA_EM-6-LOG: TFTP-SAVE : DEBUG(cli_lib) : : OUT :                                                          ^
*Sep 24 11:01:46: %HA_EM-6-LOG: TFTP-SAVE : DEBUG(cli_lib) : : OUT : % Invalid input detected at '^' marker.

Thanks for a feedback
BR
Aronne

Hello Aronne

It looks like the problem comes from the fact that there are spaces in the date portion of the file name. It is strange that the ‘^’ marker is pointing after the first space, but I would have to say that this is most likely the problem. I would suggest taking a look at this Cisco community thread that deals with a very similar configuration issue the EEM:

There you will see various options and configurations that may be helpful. You must however keep in mind that some features, such as those that can manipulate text in order to remove spaces, are supported in EEM 3.0 or higher, so you will have to check your version.

Take a look at the thread and let us know how you get along. If you need more help in the process, you know where to find us!

I hope this has been helpful!

Laz

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Hi Laz, thanks a lot for your helpful feedback :+1: .

Got another question about EEM.
I have to add a VLAN in TRUNK of multiple Switches. The only thing that helps me to discover which is the “UPLINK” where i have to put in the new VLAN in the Trunk is the description of those link.

Example:
IF G1/0/1
description DA730 - xxxxxxx
Is there a script that allows me to use the “DA” value in the description as trigger for a switchport trunk allowed vlan add command ?

Thanks again for a feedback

Aronne

Hello Aronne

Hmm, that can become involved. In order to achieve this, you need to determine which ports have the “DA” in their description. There is a command that matches a particular string that can be used.

action 3.2 cli command "show interface gigabitethernet 1/0/1"
action 3.3 string match "*description DA*" "$_cli_result"
action 3.4 puts "$_string_result

The above commands will output the results of the show interface command into the $_cli_result variable. Within that output, you will have the description.

The next command searches for a string match that contains the text “description DA” with any other text appended before and after. If it finds it, the variable $_string_result will be set to 1. Otherwise, it will be set to 0. The final command simply prints that value to the CLI. In your case, you can use that result in an if statement, to either apply the config you want to that interface or not to apply it.

More info about the string match command can be found here:

I hope this has been helpful!

Laz

Hi Laz!
Thanks for your explanation. Everytime simple and Grest!

Bye bye
Aronne

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Hi RYAN,

I’m trying to write a EEM applet which will do the following;

1- syslog msg Line protocol on Interface FastEthernet0/1, changed state to down
2- syslog msg Line protocol on Interface FastEthernet0/2, changed state to down
3- reload router

i want my router reload automatic when all lines protocol in router change to down

Hello Ridhwan

In order to achieve what you’re looking for you must find a way to determine when all line protocols have changed state to down. In order to do this, you must actively keep track of the states of the line protocols. This is not trivial but can be complex if you want to achieve it with an EEM applet. One approach would be to periodically issue the show interface description command which lists all of the interfaces, their descriptions as well as their Status and Protocol indicators like so:

image

Then you’ll have to save that output into an archive so it can then be parsed. Saving into an archive can be done like so:

archive
log config
logging enable

Once that’s done, you can then parse that archive and search for the correct number of “down” states. If the number matches the requirement, you can then issue the reload command. Now in order for this to work, you must periodically issue this command, say every several seconds, and when the condition is matched, you can issue the command you want.

Now this is one approach, there may be others that are more suitable, however, before we go into any other options, can you share with us the need for this particular operation? What are you trying to achieve with this? Maybe we can help find an alternative solution to the problem you are facing.

I hope this has been helpful!

Laz

Hi Laz
Thank you for your replay
My issue is: I have a bunch of ASR901 routers, and a lot of them got stuck, when it goes stuck , the ospf protocol goes down and i lost the connection
in addition I can not login to router and i can not do any thing
even by console .
to fix this issue i have to go to field and restart the router
so that is why i am looking for EEM command
when routers go down and all line protocol of interfaces go down
it will reload automatically
and no need to visit the field

for example i am doing now EEM command for one interface
but now i want for all interface in same time :

event manager applet OSPF_DOWN 
 event syslog pattern "Nbr 192.168.12.1 on FastEthernet0/0 from FULL to DOWN"
 action 1.0 reload

can you help
and if you have better solution can you guide us
thank you .

Hello Ridhwan

Yes, I understand your difficulty. The primary issue here is the connectivity you need to log in remotely so you can avoid having to go out into the field and restart the router. Can you create a script that tests IP connectivity with your main site? Or with the IP address of the device through which you are connecting remotely? That way you are only testing a single element rather than the line protocol going down on all interfaces.

You can use ping to test IP connectivity to an address at your main site just to confirm that connectivity is active. As soon as this is lost, for whatever reason, the device will reboot.

Now whether or not you will want to do this depends upon how often this takes place, and how many devices depend upon this particular router for connectivity. Also, if connectivity with your main site or your admin PC is lost, does that mean that all connectivity is lost, and if so, is it still OK to reboot the device? You may want to examine and weigh these issues as well to make your decision as to what event you want to cause the reboot to take place.

Finally, concerning the problem itself, you should determine what is causing this issue and resolve it. The EEM script to reboot the device should only be a temporary solution.

Let us know how you get along!

I hope this has been helpful!

Laz

A post was merged into an existing topic: IP SLA and EEM Script