Automatic Deployment and Configuration

This section contains information related to the automatic deployment and configuration features on the Cisco Nexus 3550-F Fusion (formerly ExaLINK Fusion).

The automatic deployment and configuration functionality allows a user to setup their network in such a way that new Nexus 3550-F devices added to that network will query a DHCP server to download and execute a script defined by the user. Executing this script means a user can configure or communicate to and from the Nexus 3550-F remotely at the time of deployment.

Displaying Automatic Configuration State

When inspecting the Nexus 3550-F the show auto-config command can be invoked to see the current enabled or disabled state of the automatic configuration functionality.

For Nexus 3550-F devices the initial empty configuration should look as follows:

admin@N3550-F> show auto-config
Automatic startup configuration enabled

Configuring Automatic Configuration

First enter configuration mode of the Nexus 3550-F.

admin@N3550-F> configure

When in configuration mode a user can enable this feature with the auto-config enable command.

admin@N3550-F(config)> auto-config enable
Enabled auto-configuration

To disable this feature

admin@N3550-F(config)> auto-config disable
Disabled auto-configuration

or

admin@N3550-F(config)> no auto-config
Disabled auto-configuration

Running show auto-config will now show it is in the disabled state

admin@N3550-F> show auto-config
Automatic startup configuration disabled

The automatic configuration feature will only execute when the Nexus 3550-F is connecting to a DHCP server (which is the factory default mode). This can either happen at start up or when the user configures the Nexus 3550-F for DHCP mode. To do this run management address dhcp

admin@N3550-F(config)> management address dhcp
Enabled DHCP on management interface

Remember to save the running configuration to the startup configuration if you want these settings to take remain over a reboot.

admin@N3550-F(config)> copy running-config startup-config
Saved running config to startup config

Configuring a DHCP Server

If desired when a DHCP client starts, and after it receives a DHCPOFFER response from a DHCP server, the client can communicate directly with a boot server (instead of the DHCP server) to download a boot file.

The Nexus 3550-F auto-config feature relies on this behaviour, that is its DHCP client being able to contact a DHCP server on a local LAN. The DHCP server can then be configured to provide a boot file address to the Nexus 3550-F. The Nexus 3550-F will fetch this file and apply it once downloaded. Note the boot file may have various names depending on the DHCP server e.g. boot-file, filename etc

Example script for dhcpd

#
# DHCP Server Configuration file.
#
option domain-name "autoconfig.exablaze.com";
default-lease-time 600;
max-lease-time 7200;
log-facility local7;

filename "http://192.168.111.11/fusion_autoconf.sh";

subnet 192.168.111.0 netmask 255.255.255.0 {
   range 192.168.111.111 192.168.111.130;
}

The Nexus 3550-F can download a boot file via HTTP:

filename "http://192.168.111.11/fusion_autoconf.sh";

or TFTP:

filename "tftp://192.168.111.11/fusion_autoconf.sh";

Example script files

The script files will execute as if executed by the admin user on the Nexus 3550-F. Therefore can operate standard tools like ip a, journalctl or Nexus 3550-F tools such as cli. Calling cli allows execution of commands from bash that you would normally execute through the Nexus 3550-F command line interpreter (cli)

A simple bash example to configure basic management details:

#!/bin/sh
cli -c 'configure management name-server 10.11.12.13'
cli -c 'configure hostname MYFUSION'
cli -c 'configure timesync gps'
cli -c 'configure copy running-config startup-config'

A simple bash example to configure the data path:

#!/bin/sh
cli -c 'conf patch A1 A2'
cli -c 'conf tap B1 B15'
cli -c 'conf tap B1 B16'
cli -c 'conf copy running-config startup-config'

A bash example configuring remote logging and snmp and then turning off auto-config once complete:

#!/bin/sh
cli -c 'conf snmp read community public'
cli -c 'conf snmp enable'
cli -c 'conf remote-logging target udp my-logging-server all all'
cli -c 'conf remote-logging enable'
cli -c 'conf auto-config disable'
cli -c 'conf copy running-config startup-config'

A Python example utilising the Fusion API which fetches a firmware update and applies it:

#!/usr/bin/python

# Example python script for running on Fusions
# Uses python bindings for the Fusion API
# Refer to https://exablaze.com/docs/fusion/api/ for full API details

import exalink

exalink.set_hostname(hostname='MYFUSION')
exalink.set_management_address_ipv4(mode="static", static={"address":"172.16.0.153","netmask":"255.255.255.0", "gateway":""})
exalink.save_startup_config()
exalink.update_tftp(server="172.16.0.160", file="exalink_fusion_1.9.0.tar")
# note that when update_tftp() completes it will automatically reboot the box

A Python example configuring the data path:

#!/usr/bin/python

import exalink

exalink.create_patch(ports=["A10","C1"])
exalink.create_tap(port="A16", src_port="A10", direction="input")
exalink.create_object(type="mux", name="my_mux", mode="layer2")
exalink.add_object_port(object={"type":"mux","name":"my_mux"}, port="B1", side="up")
exalink.add_object_port(object={"type":"mux","name":"my_mux"}, port="B10", side="down")
exalink.save_startup_config()

This page was last updated on May-28-2021.