System Reset

When a reset condition exists, Aboot can either reset the switch without user intervention or facilitate a manual reset through the Aboot shell. A reset operation clears the switch, including memory states and other hardware logic

  • Fixed systems: the power supply remains powered up through the reset. Power is removed from all other switch components for two to five seconds.
  • Modular systems: the power supply on the active supervisor remains powered up through the reset. Power is removed from all other supervisor components for at least one second. In Stateful Switchover (SSO) and Route Processor Redundancy (RPR) modes, resetting the standby supervisor has no effect on the active supervisor, but resetting the active supervisor causes the standby supervisor to immediately become active. After the supervisor becomes functional, it manages the power-cycling of all line cards.

The reload command initiates an immediate reset, terminating all CLI instances not running through the console port. The console port CLI displays messages that the switch generates during a reset. On modular switches with redundant supervisors, CLI sessions on the standby supervisor are not terminated.

The reload (scheduled) command schedules a reset operation to initiate at a specific time or after a specified period.

Typical Reset Sequence

The reload command power cycles the switch, then resets it under Aboot control. The hard reset clears the switch, including memory states and other hardware logic.

By default, the reload command triggers a request to store unsaved running-config commands and an option to open the Aboot shell before starting the reboot when accessing the CLI through the console port. The switch then begins the reboot process controlled by Aboot.

The following procedure is an example of a typical restart.

  1. Begin the reboot process by typing the reload command:
    The switch sends a message to confirm the reload request:
    Proceed with reload? [confirm]
  2. Press enter or type y to confirm the requested reload. Pressing any other key terminates the reload operation.
    The switch sends a series of messages, including a notification that a message was broadcast to all open CLI instances, informing them that the system is being rebooted. The reload pauses when the CLI displays the Aboot shell notification line.
    Broadcast message from root@mainStopping sshd: [ OK ] 
    SysRq : Remount R/O 
    Restarting system 
    Aboot 1.9.0-52504.EOS2.0 
    Press Control-C now to enter Aboot shell
  3. To continue the reload process, do nothing. Typing Ctrl-C opens the Aboot shell; see Aboot Commands for Aboot editing instructions.
    The switch continues the reset process, displaying messages to indicate the completion of individual tasks. The reboot is complete when the CLI displays a login prompt.
    Booting flash:/EOS.swi 
    Unpacking new kernel 
    Starting new kernel 
    Switching to rooWelcome to Arista Networks EOS 4.4.0 
    Mounting filesystems: [ OK ] 
    Entering non-interactive startup 
    Starting EOS initialization stage 1: [ OK ] 
    ip6tables: Applying firewall rules: [ OK ] 
    iptables: Applying firewall rules: [ OK ] 
    iptables: Loading additional modules: nf_conntrack_tftp [ OK ] 
    Starting system logger: [ OK ] 
    Starting system message bus: [ OK ] 
    Starting NorCal initialization: [ OK ] 
    Starting EOS initialization stage 2: [ OK ] 
    Starting ProcMgr: [ OK ] 
    Completing EOS initialization: [ OK ] 
    Starting Power On Self Test (POST): [ OK ] 
    Generating SSH2 RSA host key: [ OK ] 
    Starting isshd: [ OK ] 
    Starting sshd: [ OK ] 
    Starting xinetd: [ OK ] 
    [ OK ] crond: [ OK ] 
    switch login: 
  4. Log in to the switch to resume configuration tasks.

Switch Recovery

Aboot can automatically erase the internal flash and copy the contents of a USB drive that has been inserted before powering up or rebooting the switch. This recovery method does not require access to the switch console or Aboot password entry, even if the boot-config file lists one.

Aboot invokes the recovery mechanism only if each of these two conditions is met:

  • The USB drive must contain a file called “fullrecover.”

    The file’s contents are ignored; an empty text file is sufficient.

  • If the USB drive contains a boot-config file, its timestamp must differ from the timestamp of the boot-config file on the internal flash.

    This prevents Aboot from invoking the recovery mechanism again on every boot if you leave the flash key inserted.

To use this recovery mechanism, set up a USB drive with the files to be installed on the internal flash for example, a current EOS software image, and a customized or empty boot-config plus an empty file named “fullrecover.”

Check that the timestamp of boot-config is current to ensure that the above conditions are met.

Display Reload Cause

The show reload cause command displays the cause of the most recent system reset and lists recommended actions, if any exist, to avoid future spontaneous resets or resolve other issues that may have cause the reset.


To display the reset cause, type show reload cause at the prompt.
switch#show reload cause
Reload Cause 1:
Reload requested by the user.

Recommended Action:
No action necessary.

Debugging Information:
None available.

Configuring Zero Touch Provisioning

Zero Touch Provisioning (ZTP) is a switch configuration method that uses files referenced by a DCHP server to initially provision the switch without user intervention. A switch enters ZTP mode when it is reloaded if flash memory does not contain a startup-config.

Canceling ZTP boots the switch without using a startup-config file. When ZTP mode is canceled, a startup-config file is not stored to flash memory. Until a startup-config file is stored to flash, the switch returns to ZTP mode on subsequent reboots. This section describes steps required to implement, monitor, and cancel ZTP.

Configuring the Network for ZTP

A switch performs the following after booting in ZTP mode:

  • Configures each physical interface to no switchport mode.
  • Sends a DHCP query packet on all Ethernet and management interfaces.

After the switch receives a DHCP offer, it responds with a DHCP request for Option 66 (TFTP server name), Option 67 (bootfile name), and dynamic network configuration settings. When the switch receives a valid DHCP response, it configures the network settings, then fetches the file from the location listed in Option 67. If Option 67 returns a network URL (http:// or ftp://), the switch obtains the file from the network. If Option 67 returns a file name, the switch retrieves the file from the TFTP server listed in Option 66.

The Option 67 file can be a startup-config file or a boot script. The switch distinguishes between a startup-config file and a boot script by examining the first line in the file:

  • The first line of a boot file must consist of the #! characters followed by the interpreter path. The switch executes the code in the script, then reboots. The boot script may fetch an EOS software image or perform required customization tasks.

    The following boot file fetches an EOS software image and stores a startup configuration file to flash.

    #!/usr/bin/Cli -p2
    copy flash:startup-config
    copy flash:EOS-2.swi
    boot system flash:EOS-2.swi
  • The switch identifies any other file as a startup-config file. The switch copies the startup-config file into flash as mnt/flash/startup-config, then reboots.

    The switch uses its system MAC address as the DHCP client identifier and Arista as the Vendor Class Identifier (Option 60). When the switch receives an http URL through Option 67, it sends the following HTTP headers in the GET request:


Monitoring ZTP Progress

A switch displays the following message after rebooting when it does not contain a startup-config file:

No startup-config was found.

The device is in Zero Touch Provisioning mode and is attempting to
download the startup-config from a remote system. The device will not
be fully functional until either a valid startup-config is downloaded
from a remote system or Zero Touch Provisioning is cancelled. To cancel
Zero Touch Provisioning, login as admin and type 'zerotouch cancel'
at the CLI.

switch login:

The switch displays a CONFIG_DOWNLOAD_SUCCESS message after it successfully downloads a startup-config file, then continues the reload process as described in Typical Reset Sequence.


Successful download

Apr 15 21:36:46 switch ZeroTouch: %ZTP-5-DHCP_QUERY: Sending DHCP request on[ 
Ethernet10, Ethernet13, Ethernet14, Ethernet17, Ethernet18, Ethernet21, 
Ethernet22, Ethernet23, Ethernet24, Ethernet7, Ethernet8, Ethernet9, 
Management1, Management2 ]
Apr 15 21:36:56 switch ZeroTouch: %ZTP-5-DHCP_SUCCESS: DHCP response received on 
Ethernet24[ Mtu: 1500; Ip Address:; Nameserver:; Domain:; Gateway:; Boot File: ]
Apr 15 21:37:01 switch ZeroTouch: %ZTP-5-CONFIG_DOWNLOAD: Attempting to download 
the startup-config from
Apr 15 21:37:02 switch ZeroTouch: %ZTP-5-CONFIG_DOWNLOAD_SUCCESS: Successfully 
downloaded startup-config from
Apr 15 21:37:02 switch ZeroTouch: %ZTP-5-RELOAD: Rebooting the system
Broadcast messagStopping sshd: [OK]
watchdog is not running
SysRq : Remount R/O
Restarting system

Aboot 1.9.0-52504.EOS2.0

Press Control-C now to enter Aboot shell

ZTP Failure Notification

The switch displays a DHCP_QUERY_FAIL message when it does not receive a valid DHCP response within 30 seconds of sending the query. The switch then sends a new DHCP query and waits for a response. The switch continues sending queries until it receives a valid response or until ZTP mode is canceled.

switch login:admin
switch>Apr 15 21:28:21 localhost ZeroTouch: %ZTP-5-DHCP_QUERY: Sending DHCP 
request on[ Ethernet10, Ethernet13, Ethernet14, Ethernet17, Ethernet18, 
Ethernet21, E-thernet22, Ethernet23, Ethernet24, Ethernet7, Ethernet8, 
Ethernet9, Management1, Management2 ]
Apr 15 21:28:51 localhost ZeroTouch: %ZTP-5-DHCP_QUERY_FAIL: Failed to get a 
valid DHCP response
Apr 15 21:28:51 localhost ZeroTouch: %ZTP-5-RETRY: Retrying Zero Touch 
Provisioning from the begining (attempt 1)
Apr 15 21:29:22 localhost ZeroTouch: %ZTP-5-DHCP_QUERY: Sending DHCP request on
[ Ethernet10, Ethernet13, Ethernet14, Ethernet17, Ethernet18, Ethernet21, 
Ethernet22, Ethernet23, Ethernet24, Ethernet7, Ethernet8, Ethernet9, 
Management1, Management2 ]

Canceling ZTP Mode

To boot the switch without a startup-config file, log into the console, then cancel ZTP mode. After the switch boots, it uses all factory default settings. A startup-config file must be saved to flash memory to prevent the switch from entering ZTP mode on subsequent boots.

Configuring the Networks

If the boot-config file contains a NETDEV statement, Aboot attempts to configure the network interface, as specified by Network configuration commands. See boot-config Command Line Content for a list of commands that define the network configuration.