Chapter 6 Broadband
VMG1312-B Series User’s Guide
85
Service) can be guarant eed. ATM uses a connection-oriented m odel and est ablishes a virtual circuit
( VC) between Finding Out More
PTM
Packet Transfer Mode ( PTM) is packet-oriented and supported by the VDSL2 standard. I n PTM,
packet s are encapsulated directly in the High- level Data Link Cont rol (HDLC) frames. I t is designed
to provide a low- overhead, transparent way of transport ing packets over DSL links, as an
alternative t o ATM.
3G
3G ( Third Generation) is a digit al, packet-switched wireless t echnology. Bandwidth usage is
opt im ized as m ult iple users share t he sam e channel and bandwidt h is only allocated t o users when
t h ey send dat a. I t allows fast t r an sf er of voice and non-voice data and provides broadband I nternet
access to m obile devices.
IPv6 Introduction
I Pv6 ( I nternet Prot ocol version 6) , is designed t o enhance I P address size and feat ures. The
increase in I Pv6 address size t o 128 bit s ( from the 32-bit I Pv4 address) allow s up t o 3.4 x 10
38
I P
addresses. The Device can use I Pv4/ I Pv6 dual stack to connect to I Pv4 and I Pv6 networks, and
supports I Pv6 rapid deploym ent (6RD).
IPv6 Addressing
The 128- bit I Pv6 address is writ t en as eight 16- bit hexadecim al blocks separated by colons ( : ) . This
is an exam ple I Pv6 address 2001:0db8:1a2b:0015:0000:0000:1a2f:0000.
I Pv6 addresses can be abbreviat ed in t wo ways:
• Leading zeros in a block can be om itted. So
2001:0db8:1a2b:0015:0000:0000:1a2f:0000 can be writ t en as
2001:db8:1a2b:15:0:0:1a2f:0.
• Any num ber of consecut ive blocks of zeros can be replaced by a double colon. A double
colon can only appear once in an I Pv6 address. So
2001:0db8:0000:0000:1a2f:0000:0000:0015 can be writ t en as
2001:0db8::1a2f:0000:0000:0015, 2001:0db8:0000:0000:1a2f::0015,
2001:db8::1a2f:0:0:15 or 2001:db8:0:0:1a2f::15.
IPv6 Prefix and Prefix Length
Sim ilar t o an I Pv4 subnet m ask, I Pv6 uses an address prefix t o represent the network address. An
I Pv6 prefix length specifies how m any m ost significant bit s ( start from t he left) in the address
com pose t he net work address. The prefix lengt h is writt en as “ / x” where x is a num ber. For
exam ple,
2001:db8:1a2b:15::1a2f:0/32
m eans t hat the first 32 bits ( 2001:db8) is the subnet prefix.
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