QTECH QSW-3400 Инструкция по настройке - Manual (Page 205)

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24.2 IP Configuration
24.2.1 Introduction to IPv4, IPv6
IPv4 is the current version of global universal Internet protocol. The practice has proved that
IPv4 is simple, flexible, open, stable, strong and easy to implement while collaborating well
with various protocols of upper and lower layers. Although IPv4 almost has not been changed
since it was established in 1980’s, it has kept growing to the current global scale with the
promotion of Internet. However, as Internet infrastructure and Internet application services
continue boosting, IPv4 has shown its deficiency when facing the present scale and complexity
of Internet.
IPv6 refers to the sixth version of Internet protocol which is the next generation Internet
protocol designed by IETF to replace the current Internet protocol version 4 (IPv4). IPv6 was
specially developed to make up the shortages of IPv4 addresses so that Internet can develop
further.
The most important problem IPv6 has solved is to add the amount of IP addresses. IPv4
addresses have nearly run out, whereas the amount of Internet users has been increasing in
geometric series. With the greatly and continuously boosting of Internet services and
application devices (Home and Small Office Network, IP phone and Wireless Service
Information Terminal which make use of Internet,) which require IP addresses, the supply of IP
addresses turns out to be more and more tense. People have been working on the problem of
shortage of IPv4 addresses for a long time by introducing various technologies to prolong the
lifespan of existing IPv4 infrastructure, including Network Address Translation(NAT for short),
and Classless Inter-Domain Routing(CIDR for short), etc.
Although the combination of CIDR, NAT and private addressing has temporarily mitigated the
problem of IPv4 address space shortage, NAT technology has disrupted the end-to-end model
which is the original intention of IP design by making it necessary for router devices that serve
as network intermediate nodes to maintain every connection status which increases network
delay greatly and decreases network performance. Moreover, the translation of network data
packet addresses baffles the end-to-end network security check, IPSec authentication header
is such an example.
Therefore, in order to solve all kinds of problems existing in IPv4 comprehensively, the next
generation Internet Protocol IPv6 designed by IETF has become the only feasible solution at
present.
First of all, the 128 bits addressing scheme of IPv6 Protocol can guarantee to provide enough
globally unique IP addresses for global IP network nodes in the range of time and space.
Moreover, besides increasing address space, IPv6 also enhanced many other essential
designs of IPv4.
Hierarchical addressing scheme facilitates Route Aggregation, effectively reduces route table