Appendix E IPv6
VMG1312-B Series User’s Guide
353
Subnet Masking
Bot h an I Pv6 address and I Pv6 subnet m ask com pose of 128- bit binary digit s, which are divided
into eight 16- bit blocks and writt en in hexadecim al not ation. Hexadecim al uses four bits for each
character (1 ~ 10, A ~ F) . Each block’s 16 bits are t hen represented by four hexadecim al
characters. For exam ple, FFFF: FFFF: FFFF: FFFF: FC00: 0000: 0000: 0000.
Interface ID
I n I Pv6, an interface I D is a 64- bit identifier. I t ident ifies a physical int erface (for exam ple, an
Et hernet port) or a virtual interface ( for exam ple, t he m anagem ent I P address for a VLAN). One
interface should have a unique interface I D.
EUI-64
The EUI - 64 ( Ext ended Unique I dentifier) defined by t he I EEE ( I nst it ute of Electrical and Elect ronics
Engineers) is an int erface I D form at designed t o adapt wit h I Pv6. I t is derived from the 48- bit (6-
byt e) Et hernet MAC address as shown next . EUI - 64 inserts t he hex digit s fffe bet ween the t hird and
fourth bytes of t he MAC address and com plem ent s the sevent h bit of the first byt e of t he MAC
address. See t he following exam ple.
Identity Association
An I dentit y Associat ion ( I A) is a collection of addresses assigned to a DHCP client , through which
the server and client can m anage a set of related I P addresses. Each I A m ust be associated with
exact ly one interface. The DHCP client uses t he I A assigned t o an int erface t o obt ain configurat ion
from a DHCP server for that int erface. Each I A consists of a unique I AI D and associated I P
inform at ion.
The I A t ype is the t ype of address in t he I A. Each I A holds one type of address. I A_NA m eans an
identit y association for non- t em porary addr esses and I A_TA is an identit y association for tem porary
addresses. An I A_NA opt ion cont ains the T1 and T2 fields, but an I A_TA option does not . The
DHCPv6 server uses T1 and T2 t o cont rol the t im e at which the client contact s wit h t he server t o
extend t he lifetim es on any addresses in t he I A_NA before t he lifetim es expire. Aft er T1, t he client
sends t he server ( S1 ) ( from which the addresses in the I A_NA were obt ained) a Renew m essage. I f
FF08:0:0:0:0:0:0:0
FF09:0:0:0:0:0:0:0
FF0A:0:0:0:0:0:0:0
FF0B:0:0:0:0:0:0:0
FF0C:0:0:0:0:0:0:0
FF0D:0:0:0:0:0:0:0
FF0E:0:0:0:0:0:0:0
FF0F:0:0:0:0:0:0:0
Table 128 Reserved Mult icast Address ( cont inued)
MULTICAST ADDRESS
MAC 00 : 13 : 49 : 12 : 34 : 56
EUI - 6 4 0
2 : 13 : 49 : FF : FE : 12 : 34 : 56
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