IPv6 prefix delegation /62 subnet examples
IPv6 prefix delegation /62 subnet enables subnetting of prefixes into 4 /62 subnets for downstream router delegation. It allows manual configuration of /64 subnets on router interfaces when dynamic prefix assignment is not available.
IPv6 /62 subnet delegation configuration
This example shows the Firewall Threat Defense subnetting the prefix into 4 /62 subnets: 2001:DB8:ABCD:1230::/62, 2001:DB8:ABCD:1234::/62, 2001:DB8:ABCD:1238::/62, and 2001:DB8:ABCD:123C::/62. The Firewall Threat Defense uses one of 4 available /64 subnets on 2001:DB8:ABCD:1230::/62 for its inside network (::0). You can then manually use additional /62 subnets for downstream routers. The router shown uses 3 of 4 available /64 subnets on 2001:DB8:ABCD:1234::/62 for its inside interfaces (::4, ::5, and ::6). In this case, the inside router interfaces cannot dynamically obtain the delegated prefix, so you need to view the delegated prefix on the Firewall Threat Defense, and then use that prefix for your router configuration. Usually, ISPs delegate the same prefix to a given client when the lease expires, but if the Firewall Threat Defense receives a new prefix, you will have to modify the router configuration to use the new prefix. The DHCP unique identifier (DUID) is persistent across reboots.
