PowerEdge: Booting Server Using PXE over IPv6 in UEFI Mode

Overview

PowerEdge servers support booting several options to boot a server from a network using IPv4/IPv6:

• Preboot Execution Environment (PXE) boot - server receives configuration from a Dynamic Host Configuration Protocol (DHCP) server (DHCP is required for PXE boot) and boot using Trivial File Transfer Protocol (TFTP) protocol.
• Hypertext Transfer Protocol (HTTP) boot - server can manually specify or receive configuration from a DHCP server and boot using HTTP protocol.
• Internet Small Computer Systems Interface (iSCSI) boot - server can manually specify or receive configuration from a DHCP server and boot using iSCSI protocol.

Configuration can be specified manually for HTTP and iSCSI boot. However, for a larger number of servers, it is desirable to use DHCP.

Configuring DHCP, TFTP, HTTP server and iSCSI storage

Verify that the DHCP server is providing IP configuration to clients, including boot configuration options. Verify this with your DHCP server vendor documentation.

Boot options are documented in RFC5970 DHCPv6 Options for Network Boot. Only "boot-file-url" option is mandatory, the rest are optional. Also consult the documentation for your DHCP server vendor.

Some of the DHCP boot configuration options

Mandatory DHCP option:

• dhcp6.bootfile-url "tftp://[TFTP_server_IP]/boot_filename";
• This option specifies the boot file URL.
• Note: IPv6 address must be enclosed inside square brackets.
• Note: Username, password, or port is not supported as part of the URL.

Example:

• dhcp6.bootfile-url "tftp://[fd00::1]/boot.efi";

Other options include options to specify boot parameters, device vendor classes.

• Verify that boot files are available.
• Verify that the files configured in your DHCP configuration are available on your TFTP or HTTP server. Also verify that the server can reach the TFTP or HTTP server over IPv6 network.
  If configuring iSCSI boot, verify that the configured iSCSI volume is available. There should be one boot volume per server. Verify that the server can reach the iSCSI target over IPv6 network.
• Verify networking configuration.
• Verify that your network is configured to forward IPv6 traffic. Sometimes, network switches might not be forwarding DHCP traffic to your DHCP server by default. Check your switch vendor documentation for more information.

Multicast Listener Discovery (MLD) Snooping

MLD snooping is a feature used in IPv6 networks to prevent multicast traffic from flooding a network. MLD snooping enables a switch to listen for MLD messages and dynamically create a multicast forwarding table. This table determines which ports on the switch should receive multicast traffic.

Dell OS10 Switches

• Dell OS10 switches have ipv6 MLD Snooping enabled by default on VLAN interfaces.
• The switch may not sometimes forward DHCP requests to the DHCP server.
• Ensure that the DHCP packet is forwarded to your DHCP server, or consider to disable IPv6 MLD snooping on the configured VLAN interface for troubleshooting purposes. This may cause an increase in network traffic, as without MLD snooping multicast traffic broadcasts throughout the VLAN.
• Review documentation and configure your switches as needed.

Server configuration

UEFI boot options are configured from the system Basic Input Output System (BIOS). Alternatively, configure the BIOS setting using iDRAC.

Enter System BIOS:

• To enter System BIOS, press F2 during server reboot.
• In the BIOS, ensure that your boot mode is set to UEFI.
• In BIOS, select Network Settings and enable PXE, HTTP and iSCSI devices as per your requirements.
• When a PXE, HTTP, or ISCSI device is enabled, and if "Autoconfiguration" or "DHCP" is enabled, the server contacts DHCP server during the PXE, HTTP, or iSCSI boot sequence. PXE, HTTP, and iSCSI have options to choose between IPv4 or IPv6. Choose as required.
  • Note: Unlike UEFI boot mode, in BIOS boot mode options are configured outside BIOS in device ROM options.
  • Note: See the server operating system (OS) documentation to verify which network boot options are supported for the target OS that used on the server, and specific instructions needed for the target OS to boot properly.

Your server should be ready to boot from the network.

Troubleshooting steps

• The server reports during UEFI boot if it is received and IP address from the DHCP server.
• If the server is not getting an IP address, you may want to take a packet capture - for example using a port mirror. It is recommended to take the packet capture at the network switch interface that the server is using to boot from the network. Configure port mirror - consult your switch vendor documentation.
• Review the captured packet information with your choice of Ethernet analyzer tool.
• The error message "boot file name not provided" might indicate that the wrong protocol was sent from the DHCP server, for example "HTTP" instead of "TFTP."