WB1 9.1 IPv6 Link-Local Addressing

9.1 IPv6 Link-Local Addressing

• Configure link-local IPv6 addresses on the Frame-Relay cloud between
R1, R2, R3, R4, and R5.
• Use the IPv6 addressing format FE80::Y, where Y is the router number.

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R1:
interface Serial 0/0
ipv6 address fe80::1 link-local
frame-relay map ipv6 fe80::5 105 broadcast
frame-relay map ipv6 fe80::2 105
frame-relay map ipv6 fe80::3 105
frame-relay map ipv6 fe80::4 105

R2:
interface Serial 0/0
ipv6 address fe80::2 link-local
frame-relay map ipv6 fe80::5 205 broadcast
frame-relay map ipv6 fe80::1 205
frame-relay map ipv6 fe80::3 205
frame-relay map ipv6 fe80::4 205

R3:
interface Serial 1/0
ipv6 address fe80::3 link-local
frame-relay map ipv6 fe80::5 305 broadcast
frame-relay map ipv6 fe80::1 305
frame-relay map ipv6 fe80::2 305
frame-relay map ipv6 fe80::4 305

R4:
interface Serial 0/0/0
ipv6 address fe80::4 link-local
frame-relay map ipv6 fe80::5 405 broadcast
frame-relay map ipv6 fe80::1 405
frame-relay map ipv6 fe80::2 405
frame-relay map ipv6 fe80::3 405

R5:
interface Serial 0/0/0
ipv6 address fe80::5 link-local
frame-relay map ipv6 fe80::1 501 broadcast
frame-relay map ipv6 fe80::2 502 broadcast
frame-relay map ipv6 fe80::3 503 broadcast
frame-relay map ipv6 fe80::4 504 broadcast

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Link-local IPv6 addresses are significant only within the context of a single link.
This means that packets with link-local addresses cannot be routed between
interfaces, and link-local addresses may overlap as long as they exist on different
interfaces. The address format for IPv6 link-local addresses are FE80::/10, and
they are synonymous with the range 169.254.0.0/16 in IPv4.

Packets with link-local sources or destinations are mostly used by the router’s
control plane protocols, such as IPv6 routing protocols. For broadcast segments,
such as Ethernet, link-local reachability is implicit due to automatic resolution
through ICMP Neighbor Discovery (ICMPND). However, since multipoint NBMA
interfaces do not support Inverse ICMPND, it is necessary to ensure link-local
IPv6 address reachability over these links by configuring static mappings.
Without these mappings, routing protocols may not be able to establish
adjacencies or properly encapsulate packets.

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Rack1R5# show frame-relay map

When pinging link-local addresses it is necessary to tell the router which interface
to send traffic out. Since the link-local address can exist on multiple interfaces
the router, requires you to indicate the “Output Interface”. You must specify the
interface using the full interface name without spaces (e.g. Serial0/0/0)

Rack1R5# ping ipv6 fe80::1
Output Interface: Serial0/0Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FE80::1, timeout is 2 seconds:
Packet sent with a source address of FE80::5
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/61/80 ms