IP message fragment cache memory and forwarding method

Abstract

The invention discloses an IP message fragment caching and transmitting method, singly processing first and follow-up fragments of the message. And the course of caching the follow-up fragments is asfollows: network device caches the received follow-up fragments arriving before the first fragment into storage medium, and establishes corresponding fragment information table according to the headersof the follow-up fragments. And the invention also discloses a method for transmit IP message by the caching method, comprising the course: network device receives the first fragment of the IP messag e, makes packet filtration and establishes session table; the network device finds the fragment information table established by the follow-up fragments arriving before the first fragment; the networkdevice transmits the cached follow-up fragments according to the session table established by the first fragment; the network device adds the first fragment information into the fragment informationt able; and the network device transmits the follow-up fragments arriving after the first fragment according to the fragment information table.

Description

technical field [0001] The invention relates to a network technology, in particular to a method for caching and forwarding IP message fragments in the network. Background technique [0002] The rapid application of the Internet has exacerbated the problem of the lack of IP addresses. In order to alleviate this problem, an important application: NAT (Network Address Translation, Network Address Translation) is increasingly widely used. Through address translation, NAT enables enterprises to obtain the ability to access the Internet with only a small number of valid Internet IP addresses, which effectively alleviates the problem of insufficient addresses and provides certain security. [0003] There are two ways of network address translation: one-to-one and PAT (Port Address Translation). For one-to-one address translation, it only converts the IP address information in the message. In this mode, each internal host in the LAN needs to occupy an IP address in the address pool...

AI Technical Summary

Problems solved by technology

Therefore, for subsequent packets that arrive before the first fragment, because there is no corresponding UDP / TCP header information, the corresponding address translation cannot be performed, and the packets may not reach the correct destination; even if they can reach the correct destination, the peer end During reassembly, some of the IP headers of all fragments have undergone address translation (the first fragment and subsequent fragments received after it), and some have not performed address translation (subsequent fragments that arrive before the first fragment), and the peer end Correct reassembly cannot be performed, the sender must retransmit the corresponding message, and the subsequent retransmitted message fragments still cannot be guaranteed to be delivered in order

[0010] It can be seen that the subsequent fragments that arrive before the first fragment not only limit the correctness of address translation for IP datagrams, but also lead to a decrease in the data transmission speed of the system, which has become an obstacle to the development of network technology

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