ISC DHCPv6 config for the network boot, including support for a DHCPv6 relay request logging

dhcpd6.conf

# BEGIN DHCP Header
# ----------
# dhcpd6.conf
# ----------
default-lease-time 2592000;
preferred-lifetime 604800;
option dhcp-renewal-time 3600;
option dhcp-rebinding-time 7200;
allow leasequery;
# ----------
# Options
# ----------
option dhcp6.info-refresh-time 21600;
option dhcp6.vendor-class-identifier code 16 = string;
option dhcp6.vendor-class code 16 = {integer 32, integer 16, string};
option dhcp6.user-class code 15 = string;
option dhcp6.bootfile-url code 59 = string;
option dhcp6.client-arch-type code 61 = array of unsigned integer 16;
# Beware. this will log mac addresses without leading zeros, e.g. e6:c9:e:ea:1:75
log(info,concat(
    "DHCP6-RELAY",
    ", interface-id: ", pick-first-value(v6relay(1, option dhcp6.interface-id),""),
    ", link-layer-addr: ", v6relay(1, (binary-to-ascii(16, 8, ":", option dhcp6.client-linklayer-addr)))
    ));
# This doesn't print the MACs at all
#log(info,concat(
#    "DHCP6-RELAY",
#    ", interface-id: ", pick-first-value(v6relay(1, option dhcp6.interface-id),""),
#    ", link-layer-addr: ",
#        concat (
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,1,1))),2), ":",
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,2,1))),2), ":",
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,3,1))),2), ":",
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,4,1))),2), ":",
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,5,1))),2), ":",
#            suffix (concat ("0", binary-to-ascii (16, 8, "", substring(option dhcp6.client-linklayer-addr,6,1))),2)
#        )
#    ));
# END DHCP Header
#
# BEGIN iPXE SECTION
if exists dhcp6.user-class and
  substring(option dhcp6.user-class, 2, 4) = "iPXE" {
    option dhcp6.bootfile-url "http://tftp.server.com/secret/script.ipxe";
} else if option dhcp6.client-arch-type = 00:06 {
   option dhcp6.bootfile-url "tftp://tftp.server.com/secret/ipxe32.efi";
} else if option dhcp6.client-arch-type = 00:07 {
   option dhcp6.bootfile-url "tftp://tftp.server.com/secret/ipxe.efi";
} else if option dhcp6.client-arch-type = 00:0f {
   option dhcp6.vendor-class 0 10 "HTTPClient";
   option dhcp6.bootfile-url "http://tftp.server.com/secret/ipxe32.efi";
} else if option dhcp6.client-arch-type = 00:10 {
    option dhcp6.vendor-class 0 10 "HTTPClient";
    option dhcp6.bootfile-url "http://tftp.server.com/secret/ipxe.efi";
} else {
    # Support a hypothetical BIOS system that can PXE boot over IPv6
    option dhcp6.bootfile-url "tftp://tftp.server.com/secret/undionly.kpxe";
}
# END iPXE SECTION
# DHCP6 Pools
subnet6 2001:db8:dead::/48 {
  #pool6
  #{
  #    range6 2001:db8:dead::ffff 2001:db8:dead::ffff;
  #}
  # NAT64 recursive server - replace with your own one if needed
  option dhcp6.name-servers 2001:4860:4860::6464;
}

# If using DHCPv6 relay, the `hardware ethernet` stanza depends on the switch
# to provide the OPTION_CLIENT_LINKLAYER_ADDR (option 79) according to
# https://datatracker.ietf.org/doc/html/rfc6939
#
# On Arista switches, this is configured using
# > ipv6 dhcp relay option link-layer address
# The rest of the DHCPv6 config on Arista is just:
# interface <l3interfacename>
#   ipv6 dhcp relay destination 2001:db8:dead::beef
# where 2001:db8:dead::beef is your DHCPv6 server address
#
host server-001-uplink1 {
  hardware ethernet   e6:de:ad:be:ef:74;
  fixed-address6      2001:db8:dead::10:3;
  ddns-hostname       "server-001-uplink1";
}


host server-001-uplink2 {
  hardware ethernet   e6:de:ad:be:ef:75;
  fixed-address6      2001:db8:dead::10:5;
  ddns-hostname       "server-001-uplink2";
}


host server-002-uplink1 {
  hardware ethernet   e6:0b:ad:ca:fe:74;
  fixed-address6      2001:db8:dead::11:3;
  ddns-hostname       "server-002-uplink1";
}


host server-002-uplink2 {
  hardware ethernet   e6:0b:ad:ca:fe:75;
  fixed-address6      2001:db8:dead::11:5;
  ddns-hostname       "server-002-uplink2";
}