slides used in the hands-on lab. © 2011 cisco and/or its affiliates. all rights reserved. cisco...

Slides used in thehands-on lab

© 2011 Cisco and/or its affiliates. All rights reserved. Cisco PublicTECCRS-3000 22

EEM TCL Event Register Keywords

CLI Event Keyword…

event_register_cli sync yes|no skip yes|no [occurs ?] [period ?] pattern ? [default ?][queue_priority low|normal|high] [maxrun ?] [nice 0|1]

SYNC is a mandatory parameter, SKIP is mandatory if SYNC is set to no - the rest are optional…OCCURS can be used to indicate the number of CLI command matches before an event is raised…PERIOD indicates the time interval between sampling

If you don’t want the CLI command to be executed, set SYNC as “no” and SKIP as “yes”…

::cisco::eem::event_register_cli sync no skip yes pattern “show ip interface brief” maxrun 20

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TIMER Event Keyword…

event_register_timer watchdog|countdown|absolute|cron [name ?] [cron_entry ?] [time ?] [queue_priority low|normal|high] [maxrun ?][nice 0|1]

The type of Timer event must be specified - all other keywords are optional…

::cisco::eem::event_register_timer cron cron_entry "2 9 * * *"

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RESOURCE : CRON Information

Field Allowed Values

Minute 0-59

Hour 0-23

Day of month 1-31

Month 1-12 (or names, see table below)

Day of week 0-7 (0 or 7 is Sunday, or names, see table below)

String Meaning

@yearly Trigger once a year , “0 0 1 1 *”

@annually Same as @yearly

@monthly Trigger once a month, “0 0 1 * *”

@weekly Trigger once a week, “0 0 * * 0”

@daily Trigger once a day, “0 0 * * *”

@midnight Same as @daily

@hourly Trigger once an hour, “0 * * * *”© 2011 Cisco and/or its affiliates. All rights reserved. Cisco PublicTECCRS-3000 4



NONE Event Keyword…

event_register_none [queue_priority low|normal|high] [maxrun ?] [nice 0|1]

The one key point about this one is the use of the MAXRUN command - it defaults to 20 seconds but might need ramping up especially if dealing with conditional loops and CLI connections…

::cisco::eem::event_register_none

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EEM Environment Variables

Setting/Updating Environment VariablesEnvironment Variables can be created or modified from the CLI using the following command…

Router(config)#event manager environment chassis 6509 Router(config)#do show event manager environmentNo. Name Value 1 module 5 2 intf GigabitEthernet6/2 3 chassis 6509

LAB



EEM Writing TCL Scripts

Namespace Import…Two namespace keywords should be specified in EVERY script that you load onto a Cisco switch or router…

namespace import ::cisco::eem::*namespace import ::cisco::lib::*

These two commands import the extensions into the TCL operating environment…

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EEM TCL Basics—Creating a Variable

Variables…Can be created by using the “set” command…

set x 1

This creates the variable “x” and assigns it a value of 1

set init “abc”

This creates the variable “init” and assigns it a value of “abc”

Note: Assigning a text value necessitates enclosing the value in quotes…


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EEM TCL Basics—Referencing the Value in a Variable

Referencing the Value in a Variable…Referencing the variable value requires adding a “$” in front of the variable - consider the following…

set x 1set y $x

The second line assigns the value of variable $x to variable “y” - so $y will also inherit the value of 1


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EEM TCL Basics—Adding a Comment

Comments…Comments are invaluable to provide an understanding to other readers of the code for what the script is doing…

Comments are simply added by using a “#” at the beginning of the line

# This next block of code is used to# read in the contents of a file and place each# line into an array called $weekday


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EEM TCL Basics—Expressions

Expressions…To calculate math expressions, the “expr” command should be used - consider the following…

set x [expr 7 + 9 ]

The variable “x” is assigned the result of “7+9” - or another example

set y [expr [string length abc123] + 5 ]

The variable “y” is assigned the value of 11 as that is sum of the length in characters of the string “abc123” added to 5


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EEM TCL Basics—If-Then

If-Then…If-Then-Else is supported in TCL - a simple example

if { $name == “cisco”} { set init 1 }

The value of variable “init” will be changed to 1 if the variable $name has been set to “cisco” in an earlier part of the code (not shown)


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EEM TCL Basics—If-Then-Else

If-Then-Else…The “else” part of this option can also be used as shown in the following example…

if { $name == “cisco”} { set init 1} else { set init 2 }

Depending on the value of the variable $name, the variable $init will be set to either 1 or 2…


LAB


EEM TCL Basics—More on Arrays

Arrays continued…

The values inside the array can also be accessed using an index as shown below…

set address “10.22.134.112”set x [split $address ,\.]# note that $x[0]=10, $x[1]=22, $x[2]=134, $x[3]=112set lastbyte [lindex $x 3]

This example splits out the ip address into the 4 bytes - it assigns each byte as a unique value in the array “$x” by splitting out the values using the “.” as the delimiter - the variable “lastbyte” is then assigned the last indexed value in the array (e.g. “112”)

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EEM TCL Basics—Reading in from a File

Reading Files…

The file format should be in plain ASCII (text) format - such a file can be accessed using the following command…

set infile [open disk0:/input.txt r]

This example opens a file “input.txt” that is located on the CF card in Disk0: - the file is opened in “read-only” format which is indicated by the “r” at the end of the line - as such, data cannot be written back out to this file

The command also sets up a file handle “infile” which is used as a pointer for the file contents that are read in…

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EEM TCL Basics—Reading in from a File

Reading Files…

Lets look at how the contents of a file can be read - lets assume the file “input.txt” is loaded with the following values…

set infile [open disk0:/input.txt r]set varindex 0; set finish 0while {[gets $infile line] >= 0} { if {$line == “end”} { set finish 1 } if {$finish == 0} { set data($varindex) $line incr varindex }}

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EEM TCL Basics—Writing to a File

Writing Files…

The file format will be in plain ASCII (text) format - such a file can be created using the following command…

set data [open disk0:/output.txt w]

This example opens a file “output.txt” that is located on the CF card in Disk0: - the file is opened in “write” format which is indicated by the “w” at the end of the line

The command also sets up a file handle “data” which is used as a pointer for the file contents that are written to the file…

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EEM TCL Basics—Writing to a File

Writing Files…

To write data to a file, the command “puts” is used…

puts <filehandle> <data to be written>

Using the file created on the previous slide, the following shows how data can be written

set x 10 puts $data $x

This example writes “10” into the file pointed to by the handle $data…

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EEM TCL Basics—Closing a File

Closing Files…

After extracting the data from a file, the file should be closed - this is done as follows…

close $infile

Using the previous file example, this closes the file represented by the handle “$infile”…

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EEM TCL Basics—How to Use Event Information

EVENT_REQINFO Event Keyword…The answer lays in using “event_reqinfo”…

array set syslog_details [event_reqinfo]

set answer $syslog_details(msg)

The variable “syslog_details” is primed with values (based on the SYSLOG event_reqinfo) with variables defining the state of the SYSLOG event - then we use…

Primes the variable “$answer” with the value of “msg” in the array “syslog_details”… In other words…

$answer = “%LINK-3-UPDOWN: Interface GigabitEthernet1/48, changed state to up”

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EEM TCL Basics—Regular Expressions

Regular Expressions…Are used to perform a pattern match on the whole (or part) value of a variable and takes the following format…

regexp { <pattern match>} $var abc

This command takes the value in variable $var, matches it to the regular expression <pattern match> and places the result of the inspection into the variable “abc”…

Next - how do we specify the “pattern match”…


LAB


EEM TCL Basics—Regular Expressions

Some examples of pattern match…

^ match at beginning of string$ match at end of string. matches any literal character\x matches the character x[chars] matches any single character from char* matches zero or more of preceding atom+ matches one or more of preceding atom(abc) matches on expression abc


LAB

Example : regexp {(phone)} $Var1 Var2 will extract the word phone fromVar1 and assign it to Var2 if the value of Var1 is “I like my new cell phone”


EEM TCL Basics—Invoking CLI Commands

Accessing the CLI…Before any commands can be invoked from a script, a connection (pipe) to the CLI must be opened with the following code…

if [catch {cli_open} result] { error $result $errorInfo } else { array set cli1 $result }

LAB




Invoking a command to the CLI…A command can be invoked as follows…

if [catch {cli_exec $cli1(fd) "enable"} result] { error $result $errorInfo}if [catch {cli_exec $cli1(fd) "conf t"} result] { error $result $errorInfo}

This example shows two commands being invoked one after the after…

LAB




Closing a connection to the CLI…After the CLI commands have been invoked - the connection to the CLI must be closed - use the following code to perform this action…

if [catch {cli_close $cli1(fd) $cli1(tty_id)} result] { error $result $errorInfo}

LAB



EEM TCL Basics—Creating a Custom SYSLOG Message

Custom SYSLOG message…A custom SYSLOG message can be created as follows… action_syslog [priority emerg|alert|crit|err|warning|notice|info|debug] [msg ?]

An example is as follows…

if { $x == 1} { action_syslog msg “This is a test message”}

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EEM TCL Basics—Action Reload

Action Reload…This command can be used to force a reload of the entire switch…

An example of this follows…

if {$upgrade_complete == “yes”} { action_reload

}

action_reload


LAB


EEM Creating a TCL User Directory

Script Directory…

Scripts MUST be loaded into a registered directory in order to be successfully invoked - creating the Directory can be done using the following…

Router# mkdir EEMCreate directory filename [EEM]? Created dir flash:EEMRouter#

This example creates a directory called “EEM” on flash:

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EEM Registering a TCL User Directory

Registering a Script Directory…

After creation, the Directory must be registered - this can be done using the following…

Router(config)# event manager directory user policy flash:/EEMRouter(config)# ^ZRouter# show event manager directory user policy flash:/EEM

The Directory is now registered and can be primed with TCL scripts

LAB



EEM Registering TCL Script

Registering Scripts…

Scripts MUST be loaded into a registered directory in order to be successfully invoked - registering the script can be done using the following…

Router(config)# event manager policy <script-name> type user

Where <script-name> is the name of the script (e.g. cdp.tcl)

LAB



EEM Registering TCL Script

Viewing Registering Scripts…Scripts that have been registered can be viewed using the following command…

Router#show event manager policy registeredNo. Class Type Event Type Trap Time Registered Name1 applet system cli Off Tue Dec 19 18:29:22 2006 my_applet pattern {conf t} sync no skip no

2 script user none Off Tue Dec 19 18:29:22 2006 autoqos.tcl policyname {autoqos.tcl} nice 0 queue-priority normal maxrun 20.000

3 script user none Off Tue Dec 19 18:29:22 2006 macip.tcl policyname {macip.tcl} nice 0 queue-priority normal maxrun 200.000


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EEM EEM Show Commands

Viewing Contents of Registering Scripts…The body of scripts that have been registered can be viewed using the following command…

Router#show event manager policy available detailed macip.tcl ::cisco::eem::event_register_none maxrun 200#------------------------------------------------------------------# EEM Add Static DHCP Snooping DB entries## December 2008# Copyright (c) 2008 by Cisco Systems, Inc.# All rights reserved.#------------------------------------------------------------------#namespace import ::cisco::eem::*namespace import ::cisco::lib::*# Open pipe to CLI and enter enable mode --More--


LAB

slides used in the hands-on lab. © 2011 cisco and/or its affiliates. all rights reserved. cisco...

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