Planet XGS3-42000R User Manual page 185

Although the combination of CIDR, NAT and private addressing has temporarily mitigated the problem of IP v4
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 net work 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 IP v6 designed by IE TF has become the only feasible solution at present.
First of all, the 128 bits addressing scheme of IP v6 Protocol can guarantee to provide enough globally unique
IP addresses for global IP network nodes in the range of time and space. Moreover, besides inc reasing
address space, IP v6 also enhanced many other essential designs of IP v4.
Hierarchical addressing scheme facilitates Route A ggregation, effectively reduces route table ent ries and
enhances the efficiency and expansibility of routing and data packet processing.
The header design of IP v6 is more efficient compared with IP v4. It has less data fields and takes out header
checksum, thus expedites the processing speed of basic IP v6 header. In IP v6 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 IP v6 while obtaining a globally unique IP v6
address automatically as well which makes the devices using IP v6 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 net work operators to manage the transformation from one provider to anot her.
Support IPS ec. IPSec is optional in IP v4, but required in IP v6 Protocol. IP v6 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 calc ulating devices. The Mobile IP Protocol defined in IE TF
standard mak es mobile devices movable without cutting the existing connection, which is a network function
getting more and more important. Unlike IP v4, the mobility of IP v6 is from embedded automatic configuration
to get transmission address (Care-Of-A ddress); therefore it doesn't need Foreign Agent. Furthermore, this
kind of binding process enables Correspondent Node communicat e with Mobile Node directly, thereby avoids
the extra system cost caused by triangle routing choice required in IP v4.
Avoid the use of Net work Address Translation. The purpose of the introduction of NAT mechanism is to share
and reuse same address space among different network segments. This mechanism mitigates the problem of
the shortage of IP v4 address temporally; meanwhile it adds the burden of address translation process for
network device and application. Since the address space of IP v6 has increased greatly, address translation
becomes unnecessary, thus the problems and system cost caused by NAT deployment are solved naturally.
Support extensively deployed Routing Prot ocol. IP v6 has kept and extended the supports for existing Internal
Gateway Protocol s (IGP for short), and Exterior Gateway Protocol s (EGP for short). For ex ample, IP v6
Routing Prot ocol such as RIP ng, OSPFv3, IS-IS v6 and MBGP4+, etc.
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