When working with isolated IPv6 networks, we often need to balance technical correctness with human usability. While IPv6's 128-bit addresses offer virtually unlimited combinations, this same feature makes manual address assignment challenging for small-scale deployments.

The best practice is to use the fd00::/8 range (Unique Local Addresses - ULA) which is specifically designed for local communications:

# Example ULA prefix generation (Linux)
uuidgen | sed 's/-//g' | head -c 16
# Output might look like: fd42:8a93:71c0:b9e4

Create meaningful patterns in the interface identifier portion (last 64 bits):

Host 1: fd42:8a93:71c0:b9e4::1
Host 2: fd42:8a93:71c0:b9e4::2
Host 3: fd42:8a93:71c0:b9e4::3

Alternatively, embed decimal representations:

# For host 10 in subnet 1:
fd42:8a93:71c0:b9e4:0001::000a

Take advantage of IPv6's zero compression rules to create cleaner addresses:

# Instead of:
fd42:8a93:0000:0000:0000:0000:0000:0001

# Use compressed form:
fd42:8a93::1

For automatic interface ID generation while maintaining predictability:

# Example MAC address: 00:50:56:ab:cd:ef
# Convert to EUI-64:
fd42:8a93:71c0:b9e4:0250:56ff:feab:cdef

Even in isolated networks, consider setting up mDNS or local DNS:

# Example avahi (mDNS) configuration
<service-group>
  <name>My IPv6 Host</name>
  <service>
    <type>_ssh._tcp</type>
    <port>22</port>
    <txt-record>address=fd42::1</txt-record>
  </service>
</service-group>

Always validate your addresses:

# Python validation example
import ipaddress

def is_valid_ula(addr):
    try:
        return ipaddress.IPv6Address(addr).is_private
    except:
        return False

---

When working with isolated IPv6 LANs, we want addresses that are both technically valid and human-friendly. The best practice is to use the fc00::/7 range (Unique Local Addresses or ULAs), specifically fd00::/8 for locally assigned addresses. These are the IPv6 equivalent of IPv4's private ranges (like 10.0.0.0/8).

# Example ULA prefix generation (Linux)
uuidgen | sha1sum | cut -c 1-16
# Output might be: fd12:3456:789a:bc00::/56

For a small network (3-32 hosts), I recommend this pattern:

1. Start with fd (ULA indicator)
2. Add a simple 16-bit identifier (like 00:0001)
3. Use sequential numbering for hosts

Example assignments:

Host 1: fd00:0001::1/64
Host 2: fd00:0001::2/64
Host 3: fd00:0001::3/64

Here's how to set these addresses on different systems:

Linux (NetworkManager)

nmcli con modify "eth0" ipv6.addresses "fd00:0001::1/64"
nmcli con up "eth0"

Windows (PowerShell)

New-NetIPAddress -InterfaceAlias "Ethernet" 
    -IPAddress "fd00:0001::2" 
    -PrefixLength 64

Router Advertisement Configuration

# radvd.conf example
interface eth0 {
    AdvSendAdvert on;
    prefix fd00:0001::/64 {
        AdvOnLink on;
        AdvAutonomous on;
    };
};

After configuration, verify connectivity:

ping6 fd00:0001::2
traceroute6 fd00:0001::3

For DNS resolution, consider adding entries to /etc/hosts:

fd00:0001::1    server1
fd00:0001::2    workstation2

For slightly larger networks, you might use:

fd00:feed::1        # "feed" as identifier
fd00:cafe::1        # "cafe" pattern
fd00:1bad:babe::1   # Memorable hex words

Remember that while these patterns aren't standard, they're perfectly valid for isolated networks and make administration easier.