QTECH QSW-8300 Инструкция по настройке - Manual (Page 126)

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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
entries and enhances the efficiency and expansibility of routing and data packet processing.
The header design of IPv6 is more efficient compared with IPv4. It has less data fields and
takes out header checksum, thus expedites the processing speed of basic IPv6 header. In
IPv6 header, fragment field can be shown as an optional extended field, so that data packets
fragmentation process won’t be done in router forwarding process, and Path MTU Discovery
Mechanism collaborates with data packet source which enhances the processing efficiency of
router.
Address automatic configuration and plug-and-play is supported. Large amounts of hosts can
find network routers easily by address automatic configuration function of IPv6 while obtaining
a globally unique IPv6 address automatically as well which makes the devices using IPv6
Internet plug-and-play. Automatic address configuration function also makes the readdressing
of existing network easier and more convenient, and it is more convenient for network
operators to manage the transformation from one provider to another.
Support IPSec. IPSec is optional in IPv4, but required in IPv6 Protocol. IPv6 provides security
extended header, which provides end-to-end security services such as access control,
confidentiality and data integrity, consequently making the implement of encryption, validation
and Virtual Private Network easier.
Enhance the support for Mobile IP and mobile calculating devices. The Mobile IP Protocol
defined in IETF standard makes mobile devices movable without cutting the existing
connection, which is a network function getting more and more important. Unlike IPv4, the
mobility of IPv6 is from embedded automatic configuration to get transmission address (Care-
Of- Address); therefore it doesn’t need Foreign Agent. Furthermore, this kind of binding process