WB1 9.2 IPv6 Unique Local Addressing

9.2 IPv6 Unique Local Addressing

• Enable IPv6 processing on the links between R6 & SW1 and R3 & SW1.
• Use the ULA IPv6 prefixes FC00:X:0:67::Y/64 and FC00:X:0:37::Y/64 for
the links between SW1 & R6 and R3 & SW1 respectively.
• Here X is your rack number in decimal notation, (e.g. 10 for Rack10, not
the hex 0A) and Y is your router number (7 for SW1).

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It is necessary to change the SDM (Switch Database Manager) template for the
3560 switches in order to configure IPv6 addressing. Changes to the running
SDM preferences will be stored in memory. Reload the switch for them to take
effect.

SW1:
sdm prefer dual-ipv4-and-ipv6 routing
exit
wr
reload

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R3:
interface FastEthernet 0/0
ipv6 address FC00:1:0:37::3/64

R6:
interface FastEthernet 0/0.67
ipv6 address FC00:1:0:67::6/64

SW1:
sdm prefer dual-ipv4-and-ipv6 routing
!
interface FastEthernet 0/3
ipv6 address FC00:1:0:37::7/64
!
interface Vlan 67
ipv6 address FC00:1:0:67::7/64
!

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Unique Local IPv6 Unicast Addressing (ULA), defined in RFC 4193, deprecates
the previously used Site-Local (FEC0::/10) addressing. ULA addresses in IPv6
are synonymous with the RFC 1918 private addresses found in IPv4, i.e. the
10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 prefixes. Considered private, ULA
addresses are not publicly routable prefixes on the Internet.

The format of the ULA is:

FC00 (7 bits) + Unique ID (41 bits) + Link ID (16 bits) + Interface ID (64 bits).

The randomly generated Unique ID helps avoid address collisions. Other than
the addressing format, ULA addressing exhibits no other unique behavior when
compared to normal publicly routable IPv6 addresses.

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