IPv4, the Internet protocol (Internet Protocol, IP) in the fourth edition, is the first widely used to form the cornerstone of today's Internet protocol technology. 1981, Jon Postel defined in RFC791 IP, Ipv4 can run on a variety of underlying network, such as end-to-serial data link (PPP protocol and SLIP protocol), satellite links and so on. The most commonly used in LAN Ethernet.
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the basic structure of information protocol IP address format addresses specific length of IP routing IP packet IP packet IP header format of IPv6 and IPv4 header fields that IPv4-date information related agreements IP address of an emergency in China : The new Internet users after two years of basic information may not be
IPv4 is the Internet Protocol version 4 (Internet Protocol version 4) the title, while the Chinese referred to as The current global Internet protocol suite is used by TCP / IP protocol suite. IP is the TCP / IP protocol suite in the network layer protocol is TCP / IP protocol suite of the core agreement. The current IP protocol version number is 4 (referred to as IPv4, v, version version), which is the next version of IPv6. IPv6 is in the process of continuous development and improvement, it will in the near future replace the widely used IPv4. According to foreign media reports, the European Commission hopes that by 2010 one quarter of the European territory of its member business and government sectors and the home network into IPv6 standard. The United States has already begun with the signing of IPv6, network service providers to government departments to give conditional incentives. The EU hopes to follow the pace of the United States to promote its members in this transformation process government departments to play a leading role. Protocol Structure Version - 4-bit field that currently used IP version. IP Header Length (IHL) ─ refers to the datagram header length, with a 32-bit word length
ipv4 multicast agent
. Point to data point. Correct header minimum of 5. Type-of-Service ─ pointed out that the upper layer protocol for dealing with the current data reported to the expected quality of service, and the data reported level of importance allocated. These 8-bit field is used to assign priorities, delay, throughput and reliability. Total Length ─ specify the entire IP packet length in bytes, including data and protocol headers. The maximum value is 65,535 bytes. A typical host can receive 576 bytes of data reported. Identification ─ contains an integer that identifies the current datagram. This field is assigned by the sender of data to help focus on the receiving end the score sheet. Flags ─ constituted by the three fields, in which the two lower (least significant) control slice. Low pointed out that if the packet can be fragmented. The middle bit that in a series of fragmented packets if a packet is the last fragment. The third is the highest bit is not used. Fragment Offset ─ 13-bit field that start with the source data reported to the relevant sub-terminal location of pieces of data to support the objectives of the appropriate reconstruction of the source IP datagram. Time-to-Live ─ is a counter, discard data reported in the value of each point in turn until reduced by 1 to 0. This ensures that data packets endless loop process. Protocol ─ pointed out that in the IP process is complete, a receiver into which the upper layer protocol packets. Header Checksum ─ to help ensure the integrity of the IP protocol header. Since some header fields change, such as survival (Time to Live), which need to be recalculated for each point and testing. Internet protocol header need to be processed. Source Address ─ designated to send code. Destination Address ─ designated to receive the code. Options ─ allows IP to support various options, such as security. Data ─ including top information. IPv4 address format specified IP address length of 32 (according to TCP / IP reference model is divided), that is 2 ^ 32-1 addresses.
ipv4 the problems
general writing method of 4 decimal numbers separated by decimal points. It was also the 4-digit long integer into a decimal, but the labeling law is not common. On the other hand, IPv6 uses 128-bit address used by the address notation, it was also used in IPv4, but the use of less. Over the past IANAIP address into A, B, C, D 4 class, the 32-bit address is divided into two parts: the front part represents the network address assigned by the IANA, followed by some representatives of the local area network address. If the C class network, the first 24 bits for the network address, 8-bit address for the LAN, can provide 254 device address (because there are two addresses for the network equipment can not be used: 255 for the broadcast address, 0 for the network itself) . Network mask (Netmask) limit the scope of the network, a representative of the network part of the device address 0 for some, such as C class addresses common network mask of 255.255.255.0. Unique IP addresses - 127.xxx to the local network address to use. - 224.x.x.x for multicast addresses. - 255.255.255.255 for the general broadcast address. - 10.xxx, 172.16.xx to 172.31.xx and 192.168.xx for local network use,
chi pink dazzle limited edition, the interconnection of these networks connected to the Internet need to convert these local network address (NAT). However, this classification will be a substantial waste of available space on the network, so the new method no longer make this distinction, but the users need to use the address space, a power of 2 ways to dial with. For example, a network of 13 as long as the ip address, it will put a 16 gave him the address of the section. Assuming approval of the 61.135.136.128/16 words to that URL from 61.135.136.129 to 61.135.136.142 he can use. IP packet length of IP packets from the first (header) and the actual data part. Generally used to send the data part of the other protocols such as TCP, UDP, ICMP and so on. Data section can be up to 65,515 bytes (Byte) (= 2xx16 - 1 - minimum degree of the first 20 bytes of Ministers). In general, the lower level (link layer) will limit the features to support the IP packet length. Such as Ethernet (Ethernet) protocol, a protocol parameter, the so-called maximum transmission unit (Maximum Transfer Unit, MTU), is 1518 bytes,
CHI Turbo Ceramic Flat Iron, the Ethernet frame header with 18 bytes left to the entire IP packet ( The first part of the Department of + data), only 1500 bytes. There are some underlying network can only support a shorter packet length. In this case, IP protocol provides a partition (fragment) of the optional features. Long IP packets will be split into many short IP packets, each packet carrying a flag (Fragmentid). The sender (such as a router) will be a long IP packet fragmentation, one by one to send, transfer parties (such as another router) in accordance with the corresponding IP address and the IP divided Logo of these short packets are assembled restore the original IP packet length. Does not distinguish between IP routing Ipv4 host as a network terminal (host) and network devices such as routers in the middle of the middle of the difference. Each computer can do that do host and router. Routers used to connect different network. All linked with a router the sum of these networks is the Internet. IPv4 technology that is applicable to local area network (LAN) also applies to the wide area network. An IP packet starting from the sender to the transfer has received, often connected by a router to pass through many different networks. Each router has IP packets to transfer knowledge that recorded in the routing table. Recorded in the routing table to a different network path, each network are here as a target network. Recorded in the routing table managed by the routing protocols, such records may be static, written by the network administrator, may also be obtained by the dynamic routing protocol's. Some routing protocols can be run directly on the IP protocol. Commonly used routing protocols are - Routing Information Protocol (Routing Information Protocol, RIP), - Open Shortest Path First, Open Shortest Path Fast, OSPF), - intermediate system to intermediate system protocol (Intermediate System Intermediate System, IS-IS ),
chi iron, - Border Gateway Protocol (Border Gateway Protocol, BGP). in the network load is heavy or wrong, the router receives the IP packet can be discarded. Heavy load on the network when an IP packet as possible from the router decided to go a different path. Router for each IP packet is individually selected route. This also improves the reliability of IP communications. But the single is the IP layer of the packet transmission, and can not guarantee completely reliable. IP packets may be lost; may have duplicate IP packets are received by the receiving party; IP packets may take different paths, can not guarantee that the starting of the first; recipient may receive the IP packets being fragmented. In the TCP protocol running on top of IP to address these shortcomings is to provide a reliable data path. IP packet header format IPv4 header is usually 20 bytes long. Ethernet frames, IPv4 packet header followed by the Ethernet frame
ipv4 to ipv6 transition strategy
first, while the Ethernet frame header of the protocol type is set to 080,016. IPv4 provides different, most are rarely used option, making the IPv4 packet header can be expanded to up to 60 bytes (always 4 bytes 4 bytes of the extension). IP header field that version: 4, specify the IP protocol version number. Header length (IHL): 4 位, IP protocol header length, specifying the length of the IPv4 protocol header bytes contain the number 32. Because IPv4's header may contain a variable number of options, so this field can be used to determine the data part of the IPv4 datagram offset position. The minimum length of the IPv4 header is 20 bytes, so the minimum value of this field IHL decimal is 5 (5x4 = 20 bytes). That is, it represents the total number of bytes of header is a multiple of 4 bytes. Service Type: Defines IP protocol packet processing method, which contains the following sub-fields:: Process Field: 3, set the importance of the packet, the greater the data value of the more important range: 0 (normal ) to 7 (network control):: Delay Field: 1, Value: 0 (normal), 1 (expect low latency):: Flow Field: 1, Value: 0 (normal), 1 ( expect high traffic):: Reliability Field: 1, Value: 0 (normal), 1 (expect high reliability):: Cost Field: 1, Value: 0 (normal), 1 ( expected minimum cost):: unused: 1 Length: IP packet length ID: uniquely identifies the host to send a data segment, typically sends a data segment of each added one. But the IP packet is divided, split by the IP packet has the same logo mark: is a 3-bit control field, including::: reserved bits: one:: big dan: 1, Value: 0 ( allows data to be reported above), 1 (datagram can not be segmented):: More Dan: 1, Value: 0 (not followed by data packets package, the package for the final package), 1 (behind the more packets number of packets) of the offset: When the data segment is split, it and the more Dan (MF, More fragments) to connect, to help the destination host will be sub-package combinations. TTL: the packet on the network to survive long, each with a router that value minus one, 0 is the router discarded. Protocol: 8 bits, this field defines the data portion of IP datagram protocol type to use. Common protocols and their decimal value, including ICMP (1),
CHI Pink Dazzle Flat Iron, TCP (6), UDP (17). Checksum: 16 bits, is the IPv4 packet header
ipv4 and ipv6 connectivity
checksum. IPv6 and IPv4 IPv4 from birth to now almost no change to survive. 1983 TCP / IP protocol is used ARPAnet, until the development of the Internet later. At that time only a few hundred computers networked to each other. By 1989 the number of networked computers over 10 million units, and in the same year the 1.5Mbit / s backbone network. Because of the large address space IANA allocated to a number of companies and research institutions, some people worry that the early 90s to 10 years will be enough IP address space, and thus led to the development of IPv6. Compared with the IPv4 IPv6 has the following features and benefits: (1) larger address space. IPv4 IP address specified in the length of 32, that is 2 ^ 32-1 addresses; and IPv6 in the IP address length of 128, that is 2 ^ 128-1 addresses. Exaggeration that is, if IPV6 is widely used now, the world of every grain of sand will have a corresponding IP address. ⑵ smaller routing table. IPv6 address allocation follows the start cluster (Aggregation) principle, which makes routers used in the routing table of a record (Entry), said a subnet, which greatly reduces the length of the router in the routing table to raise the router forwarding the speed of the packet. (3) enhanced multicast (Multicast) support and the support of convection (Flow-control). This makes multimedia applications on the network has made great development opportunities, quality of service (QoS) control provides a good networking platform. (4) added to the auto-configuration (Auto-configuration) support. This is the DHCP protocol
from (5) higher level of security. In the use of IPv6 network, users can encrypt the data network layer and IP packet validation, which greatly enhances network security. Relevant agreement IPv6, TCP, UDP, ICMP, SNMP, FTP, TELNET, SMTP, ARP, RARP, RPC, XDR, NFSIPv4-date information I Pv4 address less than 400 million two years later, the remaining exhausted before all the China Internet Network Information Center ( CNNIC) said the global IP address of the Internet has just broken through the threshold of a new key, IANA IPv4 addresses can be allocated the remaining amount is less than 10%. CNNIC also called: the national level as soon as possible to speed up deployment of a smooth transition to IPv6 addresses, to avoid falling behind in the development of next-generation Internet. I CANN President and CEO Rod Beckstrom said: driven by the development of mobile Internet, there would be a huge demand for IP addresses. The next 5 years, the IP address of the mobile Internet demand is expected to reach 5-9 million. Clearly,
cheap chi straighteners, the current IPv4 address resources can not meet the rapidly growing far users demand, and if they do not take my response in time, then, operators, users and equipment providers will have a series of adverse reactions. Internet Protocol (IP) as a protocol standard for network devices connected to the network to do a unique identity. The current IP protocol version IPv4 and IPv6 is divided into two types. IPv4 and Ipv6 can provide much larger than the address of resources. Faced with such a shortage of IPv4 resources, all Internet managers should take immediate measures to promote the IPv6 network deployment plan. IP addresses are assigned one level, by the Internet Corporation for Assigned Names and addresses (ICANN) authorized by the Internet Number Authority (IANA) is responsible for allocating; IANA will assign IP addresses at the global distribution of the five regional authorities (RIRs), such as the Asia Pacific region APNIC, RIRs then allocate it to the respective management area. Less than 10% of the face of IPv4 address resources to be allocated, forcing careful consideration and the global Internet community to take resolute measures to ensure that the global transition to IPv6 gradually. After two years will face the depletion of IPv4, IPv4 to IPv6 transition implementation is imminent, the world has been the deployment of IPv6 address Working Group on the promotion of related work. In contrast, China's IPv6 incomplete industry chain. According to the latest data: China's IPv6 address is 63, ranked 18th, well behind Brazil (65 728), United States (15025), Germany (9861), Japan (8356). It is obvious, if not a positive response, China may lose in the next generation Internet based on IPv6 address of the starting line. In response to this situation, APNIC Executive Committee, CNNIC expert Zhang Jian said: To achieve a smooth transition of IPv4 to IPv6, to ensure the healthy development of China Next Generation Internet, applications in the network, terminal equipment, technical standards, IP address management on the allocation of resources have an overall layout, the government, equipment suppliers, telecom operators and content providers to fulfill their role in the IPv6 transition. In this systematic project, state power becomes an indispensable need to continuously strengthen the Government's investment in this area and policy oriented. NRO Chairman Axel Pawlik's call with this the national level, in the organization, technical standards, funding and policy, and other aspects, according to IPv4 addresses run out of time for the overall layout of the IPv6 Promotion Plan, to ensure that China can smoothly transition to next-generation IPv6 from IPv4 addresses. It is understood, CNNIC has cumulative distribution of IPv4 addresses in China 56 million Chinese IP addresses emergency: New users may be unable to access the recent two years, by the China Internet Network Information Center (CNNIC) 2008IP address resources such as research sponsored by the Chinese ipv4
number of addresses growth
seminar held in the Tianhe Software Park. The meeting said, IPv4 address assigned at the current rate of resource left over 830 days. Then, if no measures are taken, the new Internet users will not work. CNNIC IP group of international business operations director Kai explained that Internet users to the Internet must have a normal IP address, IP address to resolve domain names by browsing the web. Currently most of China are using IPv4 Internet network address, as the basic resources of the Internet, IPv4 resources are limited, has already used up 80%. Recently, the use of which China than Japan, second in the world after the United States. According to the present situation, IPv4 network addresses only the resources of more than 830 days, which means about 2010, if you do not use the new address resources, new users will not work online,
Chi dazzle flat iron, network operators can not expand the business. Kai, currently the United States has developed IPv6 network address, which is a network infrastructure resources without limit. But China's current resource use this address only education network. If you want to use the IPv6 network address, which means operators have to use the new equipment, and old equipment should be eliminated, which requires a lot of money, operators to apply for the rest of the IP address, reserves up, other users should be prepared in advance for providing the IP address of IPv6. Atlas Atlas entry for more extended reading: 1
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the conference features can be summarized as
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