Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 168)

IPv6 stateless auto-configuration
Brocade routers use the IPv6 stateless autoconfiguration feature to enable a host on a local link to
automatically configure its interfaces with new and globally unique IPv6 addresses associated with its
location. The automatic configuration of a host interface is performed without the use of a server, such
as a Dynamic Host Configuration Protocol (DHCP) server, or manual configuration.
The automatic configuration of a host interface works in the following way: a switch on a local link
periodically sends switch advertisement messages containing network-type information, such as the
64-bit prefix of the local link and the default route, to all nodes on the link. When a host on the link
receives the message, it takes the local link prefix from the message and appends a 64-bit interface
ID, thereby automatically configuring its interface. (The 64-bit interface ID is derived from the MAC
address of the host’s NIC.) The 128-bit IPv6 address is then subjected to duplicate address detection
to ensure that the address is unique on the link.
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
uses neighbor solicitation messages to verify that a unicast IPv6 address is unique.
NOTE
For the stateless auto configuration feature to work properly, the advertised prefix length in switch
advertisement messages must always be 64 bits.
The IPv6 stateless autoconfiguration feature can also automatically reconfigure a host’s interfaces if
you change the ISP for the host’s network. (The host’s interfaces must be renumbered with the IPv6
prefix of the new ISP.)
The renumbering occurs in the following way: a switch on a local link periodically sends
advertisements updated with the prefix of the new ISP to all nodes on the link. (The advertisements
still contain the prefix of the old ISP.) A host can use the addresses created from the new prefix and
the existing addresses created from the old prefix on the link. When you are ready for the host to use
the new addresses only, you can configure the lifetime parameters appropriately using the ipv6 nd
prefix-advertisement command. During this transition, the old prefix is removed from the switch
advertisements. At this point, only addresses that contain the new prefix are used on the link.
IPv6 CLI command support
IPv6 CLI command support lists the IPv6 CLI commands supported.
IPv6 CLI command support TABLE 31
IPv6 command Description Switch code Router code
clear ipv6 cache Deletes all entries in the dynamic host cache. X
clear ipv6 mld-snooping Deletes MLD-snooping-related counters or cache entries. X X
clear ipv6 neighbor Deletes all dynamic entries in the IPv6 neighbor table. X X
clear ipv6 ospf Clears OSPF-related entries. X
clear ipv6 rip Clears RIP-related entries. X
IPv6 stateless auto-configuration
168 FastIron Ethernet Switch Layer 3 Routing Configuration Guide
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