Port management seminar and computer network resources

Abstract: Internet and LAN are using a large number of TCP / IP protocol as the communication protocol, and the current IP protocol version of the main IPv4.IPv4 itself there are some shortcomings need replacement, the most prominent addresses will run out in this paper mainly discusses the IPv4 shortcomings, IPv6 features, and the issue of transition from IPv4 to IPv6 in order to better services for the modernization of port management.

Keywords: IPv4 IPv6 address network
Modern society is considered to enter the information age, computer applications deep into all aspects of society, the network port management applications are increasingly widespread, but at the same time, the computer's network resources are close to depletion, which is the computer port management or other had a direct impact of the application, so more fully tap the computer's network resources is imminent, such as port management can provide more professional services.

A, IPv4's shortcomings
1.IPv4 address resource depletion near the
In the IPv4 protocol, the 32 binary bits used to indicate the length of the IP address the same time, IP address can be roughly divided into three categories: A, B, C class, respectively, for large enterprises, medium and small businesses whose address can be distinguish between the number of networks were 128,16384,2097152, and in each network can accommodate the number of hosts were 16777216,65536,256.

Early IP address assignment, as a Class C network can only identify the 254 hosts, and hosts the majority of enterprise networks are far more than the 254 number, so they had to assign a class B address. This not only caused the IP address of the tremendous waste of resources, but also makes the Class B addresses are assigned exhausted face the same risk.

2.IPv4 routing problem
In the IPv4 packet transmitted on the Internet must choose from one network to another network route to reach their destination. The problem is the length of the routing table as the network will increase the number of variable length, while the longer routing table, router table query right the longer route, making the routing efficiency is increasingly low and this problem is more constrained than the address depletion of the Internet's growth.

3 performance has room for optimization
The original IPv4, to find the optimal method for reliable and efficient heterogeneous network data transmission, so that different computers and heterogeneous networks to interoperate, but in fact in many parts of IPv4 performance can be optimized and improvements, such as on the maximum transmission unit settings, IP header design, test and use, IP options to optimize the application of room for both.

4 security to be improved
With virtual private network software and hardware products introduced to broaden the original agreement and the security mechanism of the tunnel, but also makes the IP security issues have become increasingly exposed, such as encryption to the application layer, then open a lot of information because it involved some of the processes and information systems to carry it through the IP data was leaked, although the application layer data itself is encrypted.

5 Mobility and management support
In the early Internet, most computer systems through the static connection to the interconnection with the Internet, little changed and the reality of work and because computers increasingly mobile, the corresponding requirements are getting higher and higher Although IPv4 is also made according to practical needs some changes, but in fact, IPv4 does not have support for mobility and network management capabilities, based on its efforts to be futile.

6.IPv4 option problems
As the IPv4 header has a variable length, used to describe the special features of the option field, but many of the packets does not support IP option, the router will usually not recognize these packets as a special case be shelved, and only In no effect on the overall performance of the router to recognize and deal with it, therefore, IPv4 option a greater impact on performance, so their use is also severely affected.

Two, IPv6 features
IPv6 compared to IPv4 improvement can mainly be reflected in the following five areas:
1 Extended Address
IPv6 and IPv4 have a different address format. IPv6 IP address of a section constituted by the eight address, each address contains 16 bits, with 4 hexadecimal digits, and use a colon to separate the sections with the section in addition to 128 address resource space, IPv6 also called aggregatable global unicast address, which is a kind of hierarchical structure of the address, designed specifically for point to point communication.

128-bit IPv6 address identifier with the specified interfaces and interface groups it can be divided into three types of addresses: unicast (one single interface has a corresponding identifier, any broadcast (typically belonging to different nodes of a set of interfaces a identifier, multicast (usually belonging to different nodes of a set of interfaces with an identifier. IPv6 address structure in addition to the 32-bit address space extends to 128, but also to adjust the IP host may receive different types of addresses. such as IPv6 anycast address is replaced with a broadcast address.

2. Simplified header format
IPv6 contains eight fields (two of which are the source and destination addresses, length of 40 bytes, while in IPv4, including the option length is 60 bytes, the length is 20 bytes without options , but at least 12 different fields. IPv6 header format by using such as fixed, and processed to reduce the need to check the number of fields and other methods, it has a higher routing efficiency and unity of all the header length header also makes more To simplify, change the IP of some of the work, header length field is no longer needed.

3 also support the expansion and options
In IPv4, the IP header of the tail can add an option, but Pv6 in a separate extension header added options so that only when necessary, will be head of the inspection and treatment options.

In a variety of IPv6 extension headers are different for the standard definition, that they should be marked next header field value to identify, and each head should be optional, and only when more than one head appears, they must be inherent in the back of the head was the location close to the same time, extended header should be added to the basic IP packet header, this is the header for the extended special treatment.

4 flow identification
In IPv4, all packets of roughly equal treatment, which means that each packet by the intermediate routers in their own way to deal with. Router does not specifically record of how the future of the package deal, because it does not follow a random two packets sent between hosts, but in IPv6, the realization of the concept of flow, so that the intermediate routers a special treatment of these packets possible, where the flow is the time from a particular source to a specific destination to send the packet sequence. Links to free download http://www.hi138.com 5. to improve the safety performance of
IPv6 security expansion in two secure improved performance: IP Authentication Header and IP Encapsulating Security Payload. Authenticate the message digest function is implemented, its security and reliability of packet inspection and calculations, while Encapsulating Security through encrypted IP packet payload, or encrypt the entire IP packet, and then tunneled over the Internet for transmission, in order to achieve security.

Three, IPv4 to IPv6 transition
As a new generation IP protocol, IPv6's fundamental purpose is to replace IPv4. But completely replace IPv4 in IPv6 before, will inevitably co-exist there is a dual-protocol period. How to coordinate the exchange between the co-existence, is an important issue.

1 Dual Stack
Dual-stack network side, it is IPv6 and IPv4 service access key. Meanwhile, the mobile terminal without the translator's network, you want to visit both IPv6 and IPv4 services, must be double-stack can. Operators should also be the network edge router into a dual-stack router.

2 tunneling
Tunneling is the transmission side in the bag packaging IPv4 IPv6, and IPv4 destination will be reopened to obtain the corresponding IPv6 packets.

3 translation technology
In IPv4 network address translation is similar, translator services often end damage, and often the network potential single point of failure, so, before the translator should use a transparent terminal, and after careful measurement, otherwise, it need to modify the appropriate translator.

IV Conclusion
IPv4 with a range of issues facing the popularity of computers and the increasing number of users have become increasingly prominent, the most obvious is the IP address resources, exhausted, and some other issues, such as performance and security issues, road selection efficiency appliances low issues, IP options support issues, mobility and network management capabilities to support issues the same time, IPv6 to IPv4 has been improved in many aspects, such as the address of the development, simplified header format, support the expansion and pre-selection, authentication and confidentiality, and flow identification, etc. So, to gradually replace IPv4 with IPv6 to become the universal network layer protocol can greatly optimize network resources to better serve the modernization of port management services.

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