Configuring Zero Touch Provisioning

Zero Touch Provisioning (ZTP) works as a Third Party App (TPA) in Route-Switch Processor (RSP) and Route Processor (RP). ZTP was designed to perform two different operations:

  • Download and apply an initial configuration.

  • Download and execute a shell script.

If the downloaded file content starts with !! IOS XR it is considered as a configuration file, and ZTP performs apply_config action on the configuration file.

If the downloaded file content starts with #! /bin/bash, #! /bin/sh or #!/usr/bin/python it is considered as a script file, and ZTP executes the script.

ZTP works as following:

  1. XR scripts that run on boot, invoke DHCP request.

  2. DHCP server returns either a user script or configuration file.

  3. Download the user script or configuration file.

  4. Execute the downloaded user script or apply the downloaded configuration.

When ZTP process encounters any error, or when ZTP quits or terminates, it revert to the initial configuration that exists before starting of ZTP process.


Note

  • When initiated, ZTP checks if the system start-up configuration is applied. If startup configuration is not applied, ZTP waits for 10 minutes before proceeding.

  • To boot an image through ZTP, configure the ROMMON reboot mode option to 3.


ZTP Switches between Management and Data Port

From Cisco IOS XR Release 6.5.1, during the fresh boot of a router, auto ZTP process is initiated from the management port and switches to data port. The following events cause the ZTP process to switch between management and data port:

  • When ZTP does not find an active interface.

  • When ZTP does not receive DHCP response and time elapsed since dhclient started is greater than 128 seconds.

  • When ZTP encounters an error.

The below flow diagram illustrates the ZTP process.

Figure 1. ZTP Process Flow Sequence

Note

  • During fresh boot or manual invocation, ZTP enables IPv6 on all data port interfaces in the dataport mode.

  • The auto breakout mode is not supported.

  • Starting from Cisco IOS XR Release 6.5.1, auto data port is supported.


Manual ZTP Invocation

Manual Zero Touch Provisioning (ZTP) can be invoked manually via CLI commands. This manual way helps you to provision the router in stages. Ideal for testing out ZTP configuration without a reboot. If you would like to invoke a ZTP on an interfaces(data ports or management port), you don't have to bring up and configure the interface first. You can execute the ztp initiate command, even if the interface is down, ZTP script will bring it up and invoke dhclient. So ZTP could run over all interfaces no matter it is up or down.

Use the ztp initiate , ztp breakout , ztp terminate , and ztp clean commands to force ZTP to run over more interfaces.

  • ztp initiate — Invokes a new ZTP session. Logs can be found in /var/log/ztp.log.

  • ztp terminate —Terminates any ZTP session in progress.

  • ztp clean —Removes only the ZTP state files.

    From release 6.2.3, the log file ztp.log is saved in /var/log folder, and a copy of log file is available at /disk0:/ztp/ztp.log location using a soft link. However, executing ztp clean clears files saved on disk and not on /var/log folder where current ZTP logs are saved. In order to have a log from current ZTP run, you must manually clear the ZTP log file from /var/log/ folder.

For more information of the commands, see the ZTP command chapter in the .

This task shows the most common use case of manual ZTP invocation: invoke 4x10 breakout discovery and ZTP.

Procedure

  Command or Action Purpose
Step 1

ztp breakout

Example:


RP/0/RP0/CPU0:router# ztp breakout

Tries the 4x10 breakout on 100 GE interfaces that supports breakout and are operationally down after no-shut. If the 10x10 breakout configure brings any 10GE interface operationally up, the breakout configuration is retained; if not, the breakout configuration is reverted.

Step 2

ztp initiate dataport

Example:


RP/0/RP0/CPU0:router# ztp initiate dataport

Wed Apr 22 10:52:24.417 UTC
Invoke ZTP? (this may change your configuration) [confirm] [y/n] :y
ZTP will now run in the background.
ZTP might bring up the interfaces if they are in shutdown state.
Please use "show logging" or look at /var/log/ztp.log to check progress.

Invokes DHCP sessions on all data ports that are either up or could be brought up. ZTP runs in the background.

Authentication on Data Ports

On fresh boot, ZTP process is initiated from management ports and may switch to data ports. To validate the connection with DHCP server, authentication is performed on data ports through DHCP option 43 for IPv4 and option 17 for IPv6. These DHCP options are defined in option space and are included within dhcpd.conf and dhcpd6.conf configuration files. You must provide following parameters for authentication while defining option space:

  • Authentication code—The authentication code is either 0 or 1; where 0 indicates that authentication is not required, and 1 indicates that MD5 checksum is required.

  • Client identifier—The client identifier must be 'exr-config'.

  • MD5 checksum—This is chassis serial number. It can be obtained using echo -n $SERIALNUMBER | md5sum | awk '{print $1}' .

Here is the sample dhcpd.conf configuration. In the example below, the option space called VendorInfo is defined with three parameters for authentication:
class "vendor-classes" {
   match option vendor-class-identifier;
}

option space VendorInfo;
option VendorInfo.clientId code 1 = string;
option VendorInfo.authCode code 2 = unsigned integer 8;
option VendorInfo.md5sum code 3 = string
option vendor-specific code 43 = encapsulate VendorInfo;
subnet 10.65.2.0 netmask 255.255.255.0 {
  option subnet-mask 255.255.255.0;
  option routers 10.65.2.1;
  range 10.65.2.1 10.65.2.200;
}
host xrv9k-1-mgmt {
   hardware ethernet 00:50:60:45:67:01;
   fixed-address 10.65.2.39;
   vendor-option-space VendorInfo;
   option VendorInfo.clientId "exr-config";
   option VendorInfo.authCode 1;
   option VendorInfo.md5sum "aedf5c457c36390c664f5942ac1ae3829";
   option bootfile-name "http://10.65.2.1:8800/admin-cmd.sh";
}

ZTP Bootscript

If you want to hard code a script to be executed every boot, configure the following.


conf t
    ztp bootscript /disk0:/myscript
commit

The above configuration will wait for the first data-plane interface to be configured and then wait an additional minute for the management interface to be configured with an IP address, to ensure that we have connectivity in the third party namespace for applications to use. If the delay is not desired, use:


conf t
    ztp bootscript preip /disk0:/myscript
commit

Note

When the above command is first configured, you will be prompted if you wish to invoke it now. The prompt helps with testing.


This is the example content of /disk0:/myscript:

#!/bin/bash
exec &> /dev/console # send logs to console 
source /pkg/bin/ztp_helper.sh
 
# If we want to only run one time: 
xrcmd "show running" | grep -q myhostname
if [[ $? -eq 0 ]]; then
    echo Already configured
fi
 
# Set the hostname
cat >/tmp/config <<%%
!! XR config example
hostname myhostname
%%
xrapply /tmp/config
 
#
# Force an invoke of ZTP again. If there was a username normally it would not run. This forces it.
# Kill off ztp if it is running already and suppress errors to the console when ztp runs below and
# cleans up xrcmd that invokes it. ztp will continue to run however.
#
xrcmd "ztp terminate noprompt" 2>/dev/null
xrcmd "ztp initiate noprompt" 2>/dev/null

ZTP Utilities

ZTP includes a set of shell utilities that can be sourced within the user script. ztp_helper.sh is a shell script that can be sourced by the user script. ztp_helper.sh provides simple utilities to access some XR functionalities. Following are the bash functions that can be invoked:

  • xrcmd—Used to run a single XR exec command:
    xrcmd “show running”
  • xrapply—Applies the block of configuration, specified in a file:
    
    cat >/tmp/config <<%%
    !! XR config example
    hostname node1-mgmt-via-xrapply
    %%
    xrapply /tmp/config
  • xrapply_with_reason—Used to apply a block of XR configuration along with a reason for logging purpose:
    
    cat >/tmp/config <<%%
    !! XR config example
    hostname node1-mgmt-via-xrapply
    %%
    xrapply_with_reason "this is a system upgrade" /tmp/config
  • xrapply_string—Used to apply a block of XR configuration in one line:
    
    xrapply_string "hostname foo\ninterface GigabitEthernet0/0/0/0\nipv4 address 1.2.3.44 255.255.255.0\n"
  • xrapply_string_with_reason—Used to apply a block of XR configuration in one line along with a reason for logging purposes:
    
    xrapply_string_with_reason ”system renamed again" "hostname venus\n interface TenGigE0/0/0/0\n ipv4 address 172.30.0.144/24\n”
  • xrreplace—Used to apply XR configuration replace in XR namespace via a file.

    
    cat rtr.cfg <<%%
    !! XR config example
    hostname node1-mgmt-via-xrreplace
    %%
    xrreplace rtr.cfg
  • admincmd—Used to run an admin CLI command in XR namespace. Logs can be found in /disk0:/ztp/ztp_admincmd.log

  • xrapply_with_extra_auth—Used to apply XR configuration that requires authentication, in XR namespace via a file. The xrapply_with_extra_auth API is used when configurations that require additional authentication to be applied such as alias, flex groups.

    
    cat >/tmp/config <<%%
    !! XR config example
    alias exec alarms show alarms brief system active
    alias exec version run cat /etc/show_version.txt
    %%
    xrapply_with_extra_auth >/tmp/config 
    
    
  • xrreplace_with_extra_auth—Used to apply XR configuration replace in XR namespace via a file The xrreplace_with_extra_auth API is used when configurations that require additional authentication to be applied such as alias, flex groups

    
    cat >/tmp/config <<%%
    !! XR config example
    alias exec alarms show alarms brief system active
    alias exec version run cat /etc/show_version.txt
    %%
    xrreplace_with_extra_auth >/tmp/config 

Examples

ZTP logs its operation on the flash file system in the directory /disk0:/ztp/. ZTP logs all the transaction with the DHCP server and all the state transition. Prior executions of ZTP are also logged in /disk0:/ztp/old_logs/.

The following example displays the execution of a simple configuration script downloaded from a data interface using the command ztp initiate interface Ten 0/0/0/0 verbose , this script will unshut all the interfaces of the system and configure a load interval of 30 seconds on all of them.


#!/bin/bash
#############################################################################
# *** Be careful this is powerful and can potentially destroy your system ***
#                *** !!! Use at your own risk !!! ***
#
# Script file should be saved on the backend HTTP server
#############################################################################

source ztp_helper.sh
config_file="/tmp/config.txt"
interfaces=$(xrcmd "show interfaces brief")

function activate_all_if(){
  arInt=($(echo $interfaces | grep -oE '(Te|Fo|Hu)[0-9]*/[0-9]*/[0-9]*/[0-9]*'))
  for int in ${arInt[*]}; do
    echo -ne "interface $int\n no shutdown\n load-interval 30\n" >> $config_file
  done
  xrapply_with_reason "Initial ZTP configuration" $config_file
}

### Script entry point
if [ -f $config_file ]; then
  /bin/rm -f $config_file
else
  /bin/touch $config_file
fi
activate_all_if;
exit 0

The following example displays the ZTP logging output:


Oct 11 11:05:38 172.30.0.54 ztp-script: Hello from ncs-560-c !!!
Oct 11 11:05:40 172.30.0.54 ztp-script: current=6.1.1, desired=6.1.1
Oct 11 11:05:40 172.30.0.54 ztp-script: Version match, proceeding to configuration
Oct 11 11:05:41 172.30.0.54 ztp-script: Starting autoprovision process...
Oct 11 11:05:42 172.30.0.54 ztp-script: ### XR K9SEC INSTALL ###
Oct 11 11:05:44 172.30.0.54 ztp-script: ### Downloading complete ###
Oct 11 11:05:55 172.30.0.54 ztp-script: Waiting for k9sec package to be activated
Oct 11 11:06:01 172.30.0.54 ztp-script: ### XR K9SEC INSTALL COMPLETE ###
Oct 11 11:06:03 172.30.0.54 ztp-script: ### Installing midnight commander ###
Oct 11 11:06:04 172.30.0.54 ztp-script: ### Downloading system configuration ###
Oct 11 11:06:05 172.30.0.54 ztp-script: ### Downloading system configuration complete ###
Oct 11 11:06:06 172.30.0.54 ztp-script: ### Applying initial system configuration ###
Oct 11 11:06:11 172.30.0.54 ztp-script: !!! Checking for errors !!!
Oct 11 11:06:14 172.30.0.54 ztp-script: ### Applying system configuration complete ###
Oct 11 11:06:15 172.30.0.54 ztp-script: Autoprovision complete...