Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 185)

Each configured router interface on a link sends out a router advertisement message, which has a value
of 134 in the Type field of the ICMP packet header, periodically to the all-nodes link-local multicast
address (FF02::1).
A configured router interface can also send a router advertisement message in response to a router
solicitation message from a node on the same link. This message is sent to the unicast IPv6 address of
the node that sent the router solicitation message.
At system startup, a host on a link sends a router solicitation message to the all-routers multicast
address (FF01). Sending a router solicitation message, which has a value of 133 in the Type field of the
ICMP packet header, enables the host to automatically configure its IPv6 address immediately instead
of awaiting the next periodic router advertisement message.
Because a host at system startup typically does not have a unicast IPv6 address, the source address in
the router solicitation message is usually the unspecified IPv6 address (0:0:0:0:0:0:0:0). If the host has
a unicast IPv6 address, the source address is the unicast IPv6 address of the host interface sending the
router solicitation message.
Entering the ipv6 unicast-routing command automatically enables the sending of router advertisement
messages on all configured router Ethernet interfaces. You can configure several router advertisement
message parameters. For information about disabling the sending of router advertisement messages
and the router advertisement parameters that you can configure, refer to
Enabling and disabling IPv6
router advertisements on page 189 and Setting IPv6 router advertisement parameters on page 186.
Neighbor redirect messages
After forwarding a packet, by default, a router can send a neighbor redirect message to a host to inform
it of a better first-hop router. The host receiving the neighbor redirect message will then readdress the
packet to the better router.
A router sends a neighbor redirect message only for unicast packets, only to the originating node, and
to be processed by the node.
A neighbor redirect message has a value of 137 in the Type field of the ICMP packet header.
Setting neighbor solicitation parameters for duplicate address
detection
Although the stateless auto configuration feature assigns the 64-bit interface ID portion of an IPv6
address using the MAC address of the host’s NIC, duplicate MAC addresses can occur. Therefore, the
duplicate address detection feature verifies that a unicast IPv6 address is unique before it is assigned to
a host interface by the stateless auto configuration feature. Duplicate address detection verifies that a
unicast IPv6 address is unique.
If duplicate address detection identifies a duplicate unicast IPv6 address, the address is not used. If the
duplicate address is the link-local address of the host interface, the interface stops processing IPv6
packets.
NOTE
Duplicate Address Detection (DAD) is not currently supported with IPv6 tunnels. Make sure tunnel
endpoints do not have duplicate IP addresses.
You can configure the following neighbor solicitation message parameters that affect duplicate address
detection while it verifies that a tentative unicast IPv6 address is unique:
Neighbor redirect messages
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