Appendix C IPv6
GS2210 Series User’s Guide
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com bines it s int er face I D and global and subnet infor m at ion adver t ised fr om t he r out er. This is a
r out able global I P addr ess.
DHCPv6
The Dynam ic Host Configurat ion Pr ot ocol for I Pv6 ( DHCPv6, RFC 3315) is a ser ver- client pr ot ocol
t hat allow s a DHCP ser ver t o assign and pass I Pv6 net w or k addr esses, pr efixes and ot her
configurat ion infor m at ion t o DHCP client s. DHCPv6 ser ver s and client s exchange DHCP m essages
using UDP.
Each DHCP client and ser ver has a unique DHCP Unique I Dent ifier ( DUI D) , w hich is used for
ident ificat ion w hen t hey ar e exchanging DHCPv6 m essages. The DUI D is generat ed from t he MAC
addr ess, t im e, vendor assigned I D and/ or t he vendor 's pr ivat e ent er pr ise num ber r egist ered w it h
t he I ANA. I t should not change over t im e even aft er you reboot t he device.
Identity Association
An I dent it y Associat ion ( I A) is a collect ion of addr esses assigned t o a DHCP client , t hr ough w hich
t he ser ver and client can m anage a set of r elat ed I P addr esses. Each I A m ust be associat ed w it h
exact ly one int er face. The DHCP client uses t he I A assigned t o an int er face t o obt ain configurat ion
fr om a DHCP ser ver for t hat int er face. Each I A consist s of a unique I AI D and associat ed I P
infor m at ion.
The I A t ype is t he t ype of addr ess in t he I A. Each I A holds one t y pe of addr ess. I A_NA m eans an
ident it y associat ion for non- t em porar y addr esses and I A_TA is an ident it y associat ion for t em porar y
addr esses. An I A_NA opt ion cont ains t he T1 and T2 fields, but an I A_TA opt ion does not . The
DHCPv6 server uses T1 and T2 t o cont r ol t he t im e at w hich t he client cont act s w it h t he ser ver t o
ext end t he lifet im es on any addr esses in t he I A_NA befor e t he lifet im es expir e. Aft er T1, t he client
sends t he ser ver ( S1 ) ( fr om w hich t he addr esses in t he I A_NA w er e obt ained) a Renew m essage. I f
t he t im e T2 is r eached and t he ser ver does not r espond, t he client sends a Rebind m essage t o any
available server ( S2 ) . For an I A_TA, t he client m ay send a Renew or Rebind m essage at t he client 's
discr et ion.
DHCP Relay Agent
A DHCP r elay agent is on t he sam e net w or k as t he DHCP client s and helps for war d m essages
bet w een t he DHCP ser ver and client s. When a client cannot use it s link- local addr ess and a w ell-
know n m ult icast addr ess t o locat e a DHCP ser ver on it s net w ork , it t hen needs a DHCP relay agent
t o send a m essage t o a DHCP ser ver t hat is not at t ached t o t he sam e net w or k.
The DHCP relay agent can add t he r em ot e ident ificat ion ( r em ot e- I D) opt ion and t he int er face- I D
opt ion t o t he Relay- For war d DHCPv6 m essages. The r em ot e- I D opt ion car r ies a user- defined st r ing,
3.
In IPv6, all network interfaces can be associated with several addresses.
T1
T2
Renew
Rebind
Rebind
to S1
Renew
to S1
Renew
to S1
Renew
to S1
Renew
to S1
Renew
to S1
to S2
to S2
