Chapter 5
Advanced Configuration
42
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IPv6:
IPv6 is the ne w ve rsio n o f Inte rne t Pro to c o l (IP) b a se d o n
IPv4, a ne two rk-la ye r (La ye r 3) p ro to c o l tha t c o nta ins
a d d re ssing info rma tio n a nd so me c o ntro l info rma tio n
e na b ling p a c ke ts to b e ro ute d in the ne two rk.
The re a re two b a sic IP ve rsio ns: IPv4 a nd IPv6. IPv6 is a lso
c a lle d ne xt g e ne ra tio n IP o r IPng . IPv4 a nd IPv6 a re d e -
multip le xe d a t the me d ia la ye r. Fo r e xa mp le , IPv6 p a c ke ts
a re c a rrie d o ve r Ethe rne t with the c o nte nt typ e 86DD
(he xa d e c ima l) inste a d o f IPv4's 0800. The IPv4 is d e sc rib e d
in se p a ra te d o c ume nts. This d o c ume nt d e sc rib e s the IPv6
d e ta ils.
IPv6 inc re a se s the IP a d d re ss size fro m 32 b its to 128 b its, to
sup p o rt mo re le ve ls o f a d d re ssing hie ra rc hy, a muc h
g re a te r numb e r o f a d d re ssa b le no d e s, a nd simp le r a uto -
c o nfig ura tio n o f a d d re sse s. IPv6 a d d re sse s a re e xp re sse d in
he xa d e c ima l fo rma t (b a se 16) tha t a llo ws no t o nly
nume ra ls (0-9) b ut a fe w c ha ra c te rs a s we ll (a -f). A sa mp le
IPv6 a d d re ss lo o ks like : 3ffe :ffff:100:f101:210:a 4ff:fe e 3:9566.
Sc a la b ility o f multic a st a d d re sse s is intro d uc e d . A ne w typ e
o f a d d re ss c a lle d a n a nyc a st a d d re ss is a lso d e fine d , to
se nd a p a c ke t to a ny o ne o f a g ro up o f no d e s.
Two ma jo r imp ro ve me nts in IPv6 vs. v4:
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Imp ro ve d sup p o rt fo r e xte nsio ns a nd o p tio ns - IPv6
o p tio ns a re p la c e d in se p a ra te he a d e rs tha t a re
lo c a te d b e twe e n the IPv6 he a d e r a nd the tra nsp o rt
la ye r he a d e r. Cha ng e s in the wa y IP he a d e r o p tio ns
a re e nc o d e d to a llo w mo re e ffic ie nt fo rwa rd ing , le ss
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