WO2014187123A1

WO2014187123A1 - Network-coding-based self-adaptive dns zone file transmission method and system

Info

Publication number: WO2014187123A1
Application number: PCT/CN2013/089845
Authority: WO
Inventors: 邓光青; 王胜开; 孔宁; 沈烁
Original assignee: 中国科学院计算机网络信息中心
Priority date: 2013-05-23
Filing date: 2013-12-18
Publication date: 2014-11-27
Also published as: CN103259865A

Abstract

The present invention relates to a network-coding-based self-adaptive DNS zone file transmission method and system. Four modules are added to an existing DNS master server, wherein the four modules are a link status monitoring module, a zone file segmentation module, a coding coefficient generation module and a zone file recoding module. A module, namely a zone file decoding module, is added to a DNS slave server. The transmission method includes: 1) in the DNS master server, segmenting an original DNS zone file into several file sub-data blocks, and detecting the link status between the master and slave servers in real time to obtain detection index data; 2) coding the file sub-blocks in a limited domain, and selecting coding coefficients to generate an M×N coding coefficient matrix; 3) according to the detection index data, randomly extracting P lines from the coding coefficient matrix to obtain a P×N matrix, wherein N≤P≤M; 4) attaching the coding coefficients to P coded data blocks, and transmitting the data blocks to the DNS slave server; and after receiving N different data blocks by the slave server, decoding the zone file to obtain the integrally transmitted zone file.

Description

一种基于网络编码的自适应 DNS区文件传输方法和*** Adaptive DNS zone file transmission method and system based on network coding

技术领域 Technical field

本发明涉及一种 DNS区文件传输方法，特别涉及一种基于网络编码的自适应 DNS区文件传输方法和***，属于 DNS***传输领域。背景技术 The present invention relates to a DNS zone file transmission method, and more particularly to an adaptive DNS zone file transmission method and system based on network coding, which belongs to the field of DNS system transmission. Background technique

DNS***是最重要的互联网基础设施之一，它由权威服务器、递归服务器以及客户端组成，权威服务器负责存储区文件，供递归服务器和客户端查询，是 DNS信息的源头。递归服务器负责接收客户端（解析器）发送的请求，然后通过向各级权威服务器发出查询请求，以获得用户需要的查询结果，最后返回给客户端的解析器。客户端可以直接向权威服务器请求资源记录，但一般通过递归服务器来查询各类资源记录，以提高响应速度。为提高服务的可扩展性与可靠性，一个区一般会部署多个权威服务器，这就涉及到多个权威服务器之间的区文件同步和更新问题。在众多的权威服务器中，有一个为主服务器，其余为从服务器，主权威服务器根据用户在注册域名时提交的信息来生成区文件，并周期性地将新生成的区文件发送给从权威服务器。 The DNS system is one of the most important Internet infrastructures. It consists of authoritative servers, recursive servers, and clients. The authoritative server is responsible for storage area files for recursive server and client queries. It is the source of DNS information. The recursive server is responsible for receiving the request sent by the client (parser), and then issuing a query request to the authoritative server at each level to obtain the query result required by the user, and finally returning to the parser of the client. The client can request the resource record directly from the authoritative server, but generally queries the various resource records through the recursive server to improve the response speed. To improve the scalability and reliability of services, a zone typically deploys multiple authoritative servers, which involves zone file synchronization and update issues between multiple authoritative servers. Among the many authoritative servers, one is the master server, and the rest are the slave servers. The master authority server generates the zone file according to the information submitted by the user when registering the domain name, and periodically sends the newly generated zone file to the slave authority server. .

在现有技术中，为保证区文件传输的可靠性，从服务器首先与主服务器建立 TCP连接，然后从主服务器处下载最新的区文件。对于像 " .cn"、 " .中国"这样的顶级域来说，来自国外的查询次数已超过国内的查询次数，为提高国外用户的查询体验（即减小查询时延），一般会在国外部署从服务器，以使从服务器更加靠近用户（包括解析服务器和客户端），从而减小用户查询时延。这就涉及到主服务器与国外从服务器之间的区文件同步问题。 In the prior art, in order to ensure the reliability of the zone file transmission, the slave server first establishes a TCP connection with the master server, and then downloads the latest zone file from the master server. For top-level domains such as ".cn" and ".China", the number of queries from abroad has exceeded the number of domestic queries. In order to improve the query experience of foreign users (ie, reduce the query delay), it is generally abroad. Deploy the secondary server to bring the secondary server closer to the user (including the resolution server and client), thereby reducing user query latency. This involves the issue of zone file synchronization between the primary server and the foreign secondary server.

然而，国际链路的状况一般较差，主要体现在链路的时延长、丢包率高、网络扰动大等。这使得主服务器与国外从服务器之间的 TCP连接不太稳定，区文件许多时候存在反复重传的现象。 However, the status of international links is generally poor, mainly due to the extension of the link time, high packet loss rate, and large network disturbance. This makes the TCP connection between the primary server and the foreign secondary server less stable, and the zone file has repeated retransmissions many times.

具体来说，现有的区文件同步机制存在以下主要缺点： Specifically, the existing zone file synchronization mechanism has the following major drawbacks:

( 1 ) 由于主服务器与国外从服务器之间的链路状况很差，因此导致 TCP传输的重传率很高，即发送端（主服务器）需反复向接收端（从服务器）发送同一个数据片段，导致链路利用率很低； (1) Due to the poor link between the primary server and the foreign secondary server, the retransmission rate of the TCP transmission is very high, that is, the transmitting end (the primary server) needs to repeatedly send the same data to the receiving end (from the server). Fragment, resulting in low link utilization;

(2)一旦某次 TCP传输失败，则在进行下一次 TCP传输时，接收端在上次 TCP传输中已收到的数据将被丢弃，发送端需重新发送区文件； (2) Once a TCP transmission fails, the data received by the receiving end in the last TCP transmission will be discarded when the next TCP transmission is performed, and the transmitting end needs to resend the area file;

(3) 由于链路状况以及 TCP传输机制的特点，导致区文件传输的时间很长，影响了从服务器区文件的及时传输，给 DNS***的安全运行带来隐患 < 发明内容 (3) Due to the link status and the characteristics of the TCP transmission mechanism, the time for the file transfer is long, which affects the The timely transmission of server area files brings hidden dangers to the safe operation of the DNS system.

本发目的在于： The purpose of this report is to:

( 1 ) 减小 DNS区文件传输的粒度，防止 TCP传输失败时大段数据被丢弃； (1) Reduce the granularity of file transmission in the DNS zone to prevent large segments of data from being discarded when TCP transmission fails;

( 2 )基于网络编码的基本原理，设计高容错性的 DNS区文件传输机制，避免因链路状况差而导致的区文件重传； (2) Based on the basic principle of network coding, design a highly fault-tolerant DNS zone file transmission mechanism to avoid retransmission of zone files caused by poor link conditions;

( 3 ) 提高 DNS区文件一次传输成功率，减少区文件传输时延。 (3) Improve the success rate of one-time transmission of the DNS zone file and reduce the delay of zone file transmission.

基于上述目的，本发明提出基于网络编码的基本原理对 DNS区文件进行编码，并根据 DNS 主服务器与从服务器之间的网络拥塞程度，自适应地调整编码系数，以便尽可能提高 DNS区文件传输成功率，减小区文件传输时延。 Based on the above purpose, the present invention proposes to encode a DNS zone file based on the basic principle of network coding, and adaptively adjust the coding coefficient according to the degree of network congestion between the DNS primary server and the secondary server, so as to improve the DNS zone file transmission as much as possible. Success rate, reduced zone file transfer delay.

本发明需在现有 DNS主服务器上增加四个模块：链路状况监测模块、区文件切分模块、编码系数生成模块、区文件重编码模块；在 DNS从服务器上增加一个模块：区文件译码模块。 The invention needs to add four modules to the existing DNS main server: link status monitoring module, area file segmentation module, coding coefficient generation module, area file re-encoding module; adding a module to the DNS slave server: Code module.

本发明的核心思想是：利用网络编码的特性，通过增加冗余信息来提高区文件传输的一次成功率，避免在区文件传输过程中因链路状况不好而导致反复重传。 The core idea of the present invention is to: utilize the characteristics of network coding, increase the success rate of zone file transmission by adding redundant information, and avoid repeated retransmission due to poor link conditions during zone file transmission.

本发明的主要步骤包括： The main steps of the invention include:

1 )在 DNS主服务器上将原始 DNS区文件切分成多个文件子数据块，对主从服务器之间的链路状况进行实时检测得到检测指标数据； 1) The original DNS zone file is divided into a plurality of file sub-blocks on the DNS master server, and the link status of the master-slave server is detected in real time to obtain detection index data;

2 )在有限域中对所述文件子数据块进行编码，选择编码系数构造生成 M x N编码系数矩阵； 2) encoding the file sub-block in a finite field, selecting a coding coefficient structure to generate a matrix of M x N coding coefficients;

3 ) 根据所述检测指标数据对所述编码系数矩阵随机抽取 P行，得到 Px N矩阵， N≤P≤M； 3) randomly extract P rows from the coding coefficient matrix according to the detection index data, to obtain a Px N matrix, N≤P≤M;

4 )编码后的 ^个数据块附加编码系数并传输给 DNS从服务器；所述从服务器接收到个不同数据块后，对所接收到的子数据块进行译码得到原始 DNS区文件。 4) The encoded data blocks are added with the coding coefficients and transmitted to the DNS slave server; after receiving the different data blocks from the server, the received sub-blocks are decoded to obtain the original DNS zone file.

更进一步，所述检测的指标数据包括但不限于丢包率、往返时延。 Further, the detected indicator data includes, but is not limited to, a packet loss rate and a round trip delay.

更进一步，构造的 ^M 编码系数矩阵的构造方法包括但不限于如下方法： Further, the constructed method of the ^M coding coefficient matrix includes, but is not limited to, the following methods:

有限域中任何能满足行向量线性无关的^ >< ^矩阵皆可视为编码系数矩阵。更进一步， PxN矩阵构造方法如下: "21 Any matrix in the finite field that satisfies the linearity of the row vector is considered to be a matrix of coding coefficients. Further, the PxN matrix construction method is as follows: "21

其中，式中秩为 N，其中 P的大小由链路状况监测模块提供的丢包率与往返时延数据等决定。 Wherein, the rank is N, where the size of P is determined by the packet loss rate and round-trip delay data provided by the link condition monitoring module.

更进一步，若链路状况好于一设定阀值，则 ^值较小或 P值可为 N，若链路状况差于一设定阀值，则 P值较大或 P值可为 M。 Further, if the link condition is better than a set threshold, the value of ^ is small or the value of P can be N. If the link condition is worse than a set threshold, the P value is larger or the P value can be M. .

更进一步，对所述 PxN编码方法为： Further, the PxN encoding method is:

1) 设区文件切分模块生成了 N个文件子块，记该 N个文件子块组成的向量为： - h]- 2) 启动编码，编码过程如下： 1) The section file splitting module generates N file sub-blocks, and the vector consisting of the N file sub-blocks is: - h]- 2) Start encoding, the encoding process is as follows:

其中，为原始数据的分块，即文件子块，； _C1,_C2,...,_CP为运算后的数据； Wherein, the block of the original data, that is, the file sub-block; _C1 , _C2 , ..., _C P is the calculated data;

3 ) 编码后的数据块变为 P 块，其中 N≤P≤M ，且编码后数据块 3) The encoded data block becomes a P block, where N ≤ P ≤ M, and the encoded data block

C_; & ₂ +〜 + (¾v * w ，编码系数为"! _Ί, <½,…， <¾v ° 更进一步，所述编码后数据块 ς.需将其编码系数 , ¾v附在其数据的头部、尾部或其它指定位置发送给 DNS从服务器。 C _; & ₂ +~ + (3⁄4v * w , encoding coefficient is "! _Ί , <1⁄2,..., <3⁄4v ° Further, the encoded data block 需. its encoding coefficient, 3⁄4v is attached to its data Head, tail or other specified location is sent to the DNS slave server.

更进一步，设区文件译码模块接收到的 N个文件子块为： c ... c ], 则这 N个文件子块的编码系数构成的矩阵为： Further, if the N file sub-blocks received by the area file decoding module are: c ... c ], the matrix of the coding coefficients of the N file sub-blocks is:

— —

所述 N个文件子块的编码系数构成的矩阵的逆矩阵: "

An inverse matrix of a matrix of coding coefficients of the N file sub-blocks: "

原始数据块 i b₂ ... 可由下述方法获得: The original data block ib ₂ ... can be obtained by the following method:

将得到的文件子块 b₂ ... 进行合并后，得到原始 DNS区文件。本发明还提出一种基于网络编码的自适应 DNS区文件传输***，其特征在于，包括一 DNS 主服务器，和多个 DNS从服务器，所述 DNS主服务器上加载链路状况监测模块、区文件切分模块、编码系数生成模块以及区文件重编码模块，所述在 DNS从服务器上增加区文件译码模块； After the obtained file sub-blocks b ₂ ... are combined, the original DNS zone file is obtained. The invention also provides an adaptive DNS zone file transmission system based on network coding, which comprises a DNS primary server, and a plurality of DNS slave servers, wherein the link primary monitoring server and the zone file are loaded on the DNS primary server. a segmentation module, a coding coefficient generation module, and a zone file re-encoding module, wherein the zone file decoding module is added to the DNS slave server;

( 1 ) 链路状况监测模块：实时检测主从服务器之间的链路状况，检测的指标包括但不限于丢包率（可参见 S. Kal idindi, M. Zekauskas, etc. A One-way Packet Loss Metric for IPPM. IETF RFC 2680. ) 往返时延（可参见 S. Kal idindi, M. Zekauskas, etc. A Round-trip Delay Metric for IPPM. IETF RFC 2681. ) 等。 (1) Link condition monitoring module: Real-time detection of the link status between the master and slave servers. The detected indicators include but are not limited to the packet loss rate (see S. Kal idindi, M. Zekauskas, etc. A One-way Packet) Loss Metric for IPPM. IETF RFC 2680.) Round trip delay (see S. Kal idindi, M. Zekauskas, etc. A Round-trip Delay Metric for IPPM. IETF RFC 2681.).

( 2 )编码系数生成模块：根据链路状况监测模块提供的数据，选择合适的编码系数，编码系数的作用是与待传输的数据进行运算得到新数据。本发明所涉及的编码系数其实是一个有限域上的矩阵，这个矩阵的特点是：矩阵的各行是线性无关的。 (2) Coding coefficient generation module: According to the data provided by the link condition monitoring module, an appropriate coding coefficient is selected, and the function of the coding coefficient is to calculate new data with the data to be transmitted. The coding coefficients involved in the present invention are actually a matrix over a finite field. The characteristics of this matrix are: The rows of the matrix are linearly independent.

( 3 ) 区文件切分模块：将原始 DNS区文件切分成若干个文件子块，每个文件子块的大小可为 1兆字节，以减小文件传输的粒度，提高传输的成功率。 (3) Area file segmentation module: The original DNS zone file is divided into several file sub-blocks, and the size of each file sub-block can be 1 megabyte to reduce the granularity of file transmission and improve the success rate of transmission.

具体的切分方法如下：设区文件切分模块将原始 DNS区文件切分成 N个文件子块，则编码系数生成模块首先产生一个^ >< ^的编码系数矩阵，其中 M > N。该编码系数矩阵的特征是：矩阵是基于有限域（即伽罗华域）的，（具体可参见陈志江，董文，贾中云. 伽罗瓦域运算的软件实现. 杭州师范大学学报 (自然科学版) . 2011， 10 (5) : 466-469。) 也就是说，矩阵的所有系数都取自伽罗华域，建议选 GF(2 ); 矩阵的秩为 N ; 从该矩阵中任取 N行构成的新的 NxN矩阵的秩亦为 N，也就是说，从 MxN的编码系数矩阵任取的 N行都是线性无关的。具备该特性的以下这种构造方法： The specific segmentation method is as follows: The zone file segmentation module divides the original DNS zone file into N file sub-blocks, and the coding coefficient generation module first generates a coding coefficient matrix of ^ >< ^, where M > N. The characteristics of the coding coefficient matrix are: The matrix is based on a finite field (ie, Galois field), (see, for example, Chen Zhijiang, Dong Wen, Jia Zhongyun. Software implementation of Galois domain operations. Journal of Hangzhou Normal University (Natural Science) Edition) . 2011, 10 (5) : 466-469.) That is to say, all the coefficients of the matrix are taken from the Galois field, it is recommended to choose GF(2); the rank of the matrix is N; from the matrix N line composition The rank of the new NxN matrix is also N, that is, the N rows from the MxN coding coefficient matrix are linearly independent. The following constructor with this feature:

上式中， Μ、 Ν为矩阵的行数和列数， ^表示的1次幂； ί^-¹表示 _fl N次幂数 ¾均来自有限域， _ai≠_aj,if i≠ j。如无特殊说明，下面所涉各运算均为有限域上的运算，以减少计算量。根据范德蒙不等式（具体可参见黄朝霞. 范德蒙德行列式的推广. 集美大学学报 (自然科学版）， 2008, 13(1) :88-91) 的性质，可以轻易证明：从上述 M x N矩阵中任取 N行构成的新的 NxN矩阵的秩亦为 N，即从上述 MxN矩阵中任取的 N行向量是线性无关的。 In the above formula, Μ, Ν 1 power of the number of rows and columns of the matrix, denoted ^; ί ^ - ¹ _fl N represents the number ¾-average power from a finite _{_{field, ai ≠ aj, if i ≠}} j. Unless otherwise specified, the operations described below are operations on a finite field to reduce the amount of computation. According to Van der Monster's inequality (see Huang Zhaoxia. The promotion of Vandermonde's determinant. Journal of Jimei University (Natural Science), 2008, 13(1): 88-91) can be easily proved: From the above M x N matrix The rank of the new NxN matrix composed of N rows is also N, that is, the N row vectors taken from the above MxN matrix are linearly independent.

(4)编码系数生成模块：根据链路状况监测模块提供的丢包率与往返时延数据，从 MxN 的编码系数矩阵中随机抽取行，随机抽取的的行数与链路状况相关，构成一个新的 PxN的矩阵，其中 N≤尸≤M。尸 xN (4) Coding coefficient generation module: according to the packet loss rate and round-trip delay data provided by the link condition monitoring module, randomly extracting rows from the MxN coding coefficient matrix, and the number of randomly extracted rows is related to the link status, and constitutes a A new matrix of PxN, where N ≤ corpus ≤ M. Corpse xN

fl_u表示行数为 1，列数为 1的子块， α_1Λί表示行数为 1，列数为 Ν的子块。根据上述讨论，矩阵的秩为 N，其中 P的大小由链路状况监测模块提供的丢包率与往返时延数据决定。如果链路状况较好，则 ⁵的值较小，反之则较大；如果链路状况很好，则 ^的值可为 N，反之，如果链路状况非常差，则 ⁵的值可为。 Fl _u denotes a sub-block with 1 row number and 1 column number, and α _1Λί denotes a sub-block with 1 row number and 列 column number Ν. According to the above discussion, the rank of the matrix is N, where the size of P is determined by the packet loss rate and round-trip delay data provided by the link condition monitoring module. If the link status is good, the value of ⁵ is small, and vice versa. If the link status is good, the value of ^ can be N. Conversely, if the link status is very poor, the value of ⁵ can be.

设区文件切分模块生成了 N个文件子块，记这 N个文件子块组成的向量为： The zone file segmentation module generates N file sub-blocks, and the vector consisting of the N file sub-blocks is:

[ … (3) 接下来，区文件重编码 [... (3) Next, the zone file is re-encoded

为原始数据的分块，即文件子块，； , ^为运算后的数据 _c 编码后的数据块变为块，其中 N≤P≤M。且称系数 , a_i2, ... , «^为编码后数据块 c,的编码系数。编码后每个数据块需附加其编码系数，并传输给 DNS从服务器。例如，数据块 c,需将其编码系数 . , 附在其数据的头部、尾部或其它指定位置发送给 DNS从服务器。 The block of the original data, that is, the file sub-block, ; , ^ is the data block after the operation of the data _c , and the block becomes a block, where N ≤ P ≤ M. And The coefficient, a _i2 , ... , «^ is the encoding coefficient of the encoded data block c. After encoding, each data block needs to be appended with its encoding coefficient and transmitted to the DNS slave server. For example, the data block c needs to be sent to the DNS slave server by attaching its encoding coefficient to the header, tail or other specified location of its data.

(5)区文件重编码模块：将上述编码后的 ⁵个数据块依次或同时发送给 DNS从服务器， DNS从服务器的区文件译码模块负责接收来自 DNS主服务器区文件重编码模块发送的数据块。 DNS从服务器的区文件译码模块无需将 DNS主服务器发送的全部 P个数据块都接收后再译码，只要 DNS从服务器的区文件译码模块接收到了 W个不同的数据块，就可以启动译码，并恢复出原始信息 ¾ K … ]。也就是说，即使在传输过程中丢失了多达 0 - Λ 个的数据块， DNS从服务器的区文件译码模块依旧能恢复出原始信息，而无需反复重传，从而可以减少传输时延，提高 DNS区文件的传输成功率。 (5) Area file re-encoding module: The above-mentioned encoded ⁵ data blocks are sequentially or simultaneously sent to the DNS slave server, and the DNS file decoding module of the DNS slave server is responsible for receiving the data sent by the DNS main server area file re-encoding module. Piece. The DNS file decoding module of the DNS slave server does not need to receive all the P data blocks sent by the DNS master server, and then decodes, as long as the DNS receives W different data blocks from the server file decoding module of the server, it can be started. Decode, and restore the original information 3⁄4 K ... ]. That is to say, even if up to 0 - 数据 data blocks are lost during transmission, the DNS file decoding module of the server can still recover the original information without repeated retransmission, thereby reducing the transmission delay. Improve the transmission success rate of the DNS zone file.

DNS从服务器的区文件译码模块的译码流程如下所述：设区文件译码模块接收到的 N个文件子块为： The decoding process of the zone file decoding module of the DNS slave server is as follows: The N file sub-blocks received by the zone file decoding module are:

' ] (6) 设这 N个文件子块的编码系数构成的矩阵为： ' ] (6) Let the matrix of the coding coefficients of the N file sub-blocks be:

a a a a a a

C (7) a C (7) a

即 which is

为了解码，区文件译码模块首先求矩阵 (7)的逆矩阵: For decoding, the region file decoding module first finds the inverse matrix of the matrix (7):

C (9)

那么，原始数据块 b₂ ... b_w ]可由下述方法获得: C (9)

Then, the original data blocks b ₂ ... b _w ] can be obtained by the following methods:

区文件译码模块将得到的文件子块 b₂ ... b_w ]进行合并后，即可得到原始 DNS区文件。 The zone file decoding module combines the obtained file sub-blocks b ₂ ... b _w ] to obtain the original DNS zone file.

本发明的有益效果 Advantageous effects of the present invention

( 1 ) 以较小的粒度传输 DNS区文件，有效避免了 TCP连接中断后造成的大量数据被丢弃的现象； (1) Transmitting DNS zone files with a small granularity, effectively avoiding the phenomenon that a large amount of data is discarded after the TCP connection is interrupted;

(2)避免了主从 DNS服务器之间链路状况较差时（尤其是国际链路）造成的反复重传； (2) avoiding repeated retransmissions caused by poor link conditions between the master and slave DNS servers (especially international links);

(3) 缩短了主从 DNS服务器之间区文件传输的时延。附图说明 (3) Shorten the delay of file transfer between the master and slave DNS servers. DRAWINGS

图 1是本发明一种基于网络编码的自适应 DNS区文件传输***示意图。具体实施方式 1 is a schematic diagram of an adaptive DNS zone file transmission system based on network coding according to the present invention. detailed description

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，可以理解的是，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。 The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. It is understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. example. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

现举例说明如下： The examples are as follows:

如图 1所示是本发明一种基于网络编码的自适应 DNS区文件传输***示意图。 FIG. 1 is a schematic diagram of an adaptive DNS zone file transmission system based on network coding according to the present invention.

假设选定的有限域为 GF(2 )，即该有限域中只有 0~7这八个数；此外，下述运算皆为有限域上的运算。假设原始 DNS区文件包含的数据为： β = [0,3, 2,1, 6,7,5,3,7]，共 9个数。 DNS 区文件被切分成 3块（即 Ν=3)，这样就构成了一个矩阵 Β，如下所示： 0 3 2 Assume that the selected finite field is GF(2), that is, there are only eight numbers from 0 to 7 in the finite field; in addition, the following operations are all operations on the finite field. Assume that the original DNS zone file contains data: β = [0,3, 2,1, 6,7,5,3,7], a total of 9 numbers. The DNS zone file is split into 3 blocks (ie Ν=3), which forms a matrix Β, as shown below: 0 3 2

1 6 7 (Π) 1 6 7 (Π)

5 6 7 5 6 7

下面构造一个有限域 GF(2^A3)上的 6x3矩阵（即 M=6， N=3)，如下所示: The following constructs a 6x3 matrix on a finite field GF(2 ^A 3) (ie M=6, N=3) as follows:

假设主从 DNS服务器之间的网络状况较差，则从上述矩阵中随机挑出 5行（即 P=5)，得到个 5x3的矩阵 P，如下所示： Assuming that the network condition between the master and slave DNS servers is poor, randomly select 5 rows (ie, P=5) from the above matrix to obtain a 5x3 matrix P, as shown below:

1 0 0 1 0 0

1 1 1 1 1 1

1 2 4 (13) 1 2 4 (13)

1 3 5 1 3 5

1 5 7 1 5 7

区文件重编码模块将编码系数矩阵 (13)与原始数据 (11)相乘，得到编码后的码字 C，即 C = P*B , 如下所示： The region file re-encoding module multiplies the coding coefficient matrix (13) by the original data (11) to obtain the encoded codeword C, that is, C = P*B, as follows:

然后，区文件重编码模块将编码得到的码字 [0，3，2； 4,3,2; 0,1,6; 4,1,6; 3,4,7]与对应的编码系数发往 DNS从服务器。由于 DNS主从服务器之间的链路状况很差，导致大量的丢包，区文件重编码模块发往 DNS从服务器的 5组码字丢失了 2组，丢包率高达 67%。最终， DNS从服务器收到了 5组码字中的 3组，假设为： Then, the region file re-encoding module sends the encoded codewords [0, 3, 2; 4, 3, 2; 0, 1, 6; 4, 1, 6, 3, 4, 7] and corresponding coding coefficients. Go to DNS from the server. Due to the poor link status between the DNS master-slave server, a large number of packet loss results, the zone file re-encoding module sent to the DNS slave group 5 groups of codewords lost 2 groups, the packet loss rate is as high as 67%. Eventually, DNS received three of the five sets of codewords from the server, assuming:

0 3 2 0 3 2

0 1 6 (15) 0 1 6 (15)

3 4 7 3 4 7

此时， DNS从服务器依然可从上述 3组码字中恢复出原始信息，由于每组码字会将其对应的编码系数发送给 DNS从服务器，即码字 [0,3,2]会将其对应的编码系数 [1,0,0]、码字 [0,1,6] 会将其对应的编码系数 [1，2，4]、码字 [3,4,7]会将其对应的编码系数 [1，5，7]发送给 DNS 从服务器。这样， DNS从服务器在收到编码码字的同时会收到对应的编码系数矩阵，如下所示: At this point, the DNS slave server can still recover the original information from the above three groups of codewords, since each group of codewords will send its corresponding coding coefficient to the DNS slave server, ie the codeword [0, 3, 2] will The corresponding coding coefficients [1, 0, 0] and codewords [0, 1, 6] will correspond to their corresponding coding coefficients [1, 2, 4] and codewords [3, 4, 7]. Coding coefficients [1, 5, 7] are sent to the DNS slave service Device. In this way, the DNS slave receives the corresponding coded coefficient matrix while receiving the encoded codeword, as follows:

1 0 0 1 0 0

1 2 4 (16) 1 2 4 (16)

1 5 7 1 5 7

此时， DNS从服务器根据下述方法来恢复原始信息: At this point, the DNS slave server restores the original information according to the following methods:

首先求式 (16)的逆矩阵，所得逆矩阵如下所示： First, find the inverse matrix of equation (16). The resulting inverse matrix is as follows:

1 0 0 1 0 0

7 1 6 (17) 7 1 6 (17)

1 2 3 1 2 3

而后 DNS从服务器将式 (17)与接收到的码字矩阵 (15)相乘，即可恢复出原始信息。设式 (17) 与 (15)相乘的结果为 D，贝 I :

The DNS then multiplies equation (17) by the received codeword matrix (15) from the server to recover the original information. The result of multiplying equations (17) and (15) is D, Bay I:

由式（18 )可以看出， D与原始信息，即式 (11)是完全一样的。也就是说， DNS从服务器在丢包率高达 67%的条件下，依然能恢复出原始信息。这样就避免了反复重传，提高了区文件传输时延。 As can be seen from equation (18), D is identical to the original information, equation (11). In other words, the DNS slave server can still recover the original information under the condition that the packet loss rate is as high as 67%. This avoids repeated retransmissions and improves the zone file transmission delay.

Claims

权利要求书 Claim

1.一种基于网络编码的自适应 DNS区文件传输方法，其步骤包括： A network code-based adaptive DNS zone file transmission method, the steps comprising:

1 )在 DNS主服务器上将原始 DNS区文件切分成多个文件子数据块，对主从服务器之间的链路状况进行实时检测得到检测指标数据； 1) On the DNS primary server, the original DNS zone file is divided into multiple file sub-blocks, and the link status of the master-slave server is detected in real time to obtain detection index data;

2 ) 在有限域中对所述文件子数据块进行编码，选择编码系数构造生成 M x N编码系数矩阵； 2) encoding the file sub-data block in a finite field, and selecting a coding coefficient structure to generate an M x N coding coefficient matrix;

3 )根据所述检测指标数据对所述编码系数矩阵随机抽取 P行，得到 Px N矩阵， N≤P≤M3) randomly extract P rows from the coding coefficient matrix according to the detection index data to obtain a Px N matrix, N≤P≤M

4)编码后的 ^个数据块附加编码系数并传输给 DNS从服务器；所述从服务器接收到个不同数据块后，对所接收到的子数据块进行译码得到原始 DNS区文件。 4) The encoded data blocks are appended with the coding coefficients and transmitted to the DNS slave server; after receiving the different data blocks from the server, the received sub-blocks are decoded to obtain the original DNS zone file.

2.如权利要求 1所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，所述检测的指标数据包括丢包率、往返时延。 The network code-based adaptive DNS zone file transmission method according to claim 1, wherein the detected indicator data comprises a packet loss rate and a round trip delay.

3.如权利要求 1 所述的基于网络编码的自适应 DNS 区文件传输方法，其特征在于，构造的 ^M 编码系数矩阵的构造方法如下：

3. The network coding-based adaptive DNS zone file transmission method according to claim 1, wherein the constructed ^M coding coefficient matrix is constructed as follows:

1 ,, ,. .α 」 1 ,, ,. .α ”

上式中 Μ、 Ν为矩阵的行数和列数，数^^，…，均来自有限域， _ai≠a_pif i≠ j。 In the above formula, Μ and Ν are the number of rows and columns of the matrix, and the numbers ^^,... are all from the finite field, _ai ≠a _p if i≠ j.

4.如权利要求 1所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，所述 P x N 矩阵构造方法如下： The network coding-based adaptive DNS zone file transmission method according to claim 1, wherein the P x N matrix construction method is as follows:

其中，式中秩为 N，其中 P的大小由链路状况监测模块提供的丢包率与往返时延数据决定。Wherein, the rank is N, where the size of P is determined by the packet loss rate and round-trip delay data provided by the link condition monitoring module.

5.如权利要求 4所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，若链路状况值小于一设定阀值，则 ⁵值较小或 ⁵值可为 N，若链路状况值大于一设定阀值，则 ⁵值较大或值可为 M。 The network code-based adaptive DNS zone file transmission method according to claim 4, wherein if the link state value is less than a set threshold, the value of ⁵ is smaller or the value of ⁵ may be N, if If the link status value is greater than a set threshold, then the value of ⁵ is greater or the value can be M.

6. 如权利要求 1所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，对所述区文件的编码方法为： 1) 设区文件切分模块生成了 N个文件子块， 6. The network coding-based adaptive DNS zone file transmission method according to claim 1, wherein the encoding method of the zone file is: 1) The zone file segmentation module generates N file sub-blocks.

[ [

2) 启动编码，编码过程如下

2) Start the encoding, the encoding process is as follows

其中，为原始数据的分块，即文件子块； _Cl,c₂,...,_Cp为运算后的数据； Wherein, the block of the original data, that is, the file sub-block; _Cl , c ₂ , ..., _Cp is the calculated data;

3 ) 编码后的数据块变为 P 块，其中 N≤P≤M ，且编码后数据块 c_; = α_Ά *^+ a_i2 *b₂+... + a_iN *b_N ，编码系数为" _!Ί， <¾，…， ° 3) The encoded data block becomes a P block, where N ≤ P ≤ M, and the encoded data block c _; = α _Ά *^ + a _i2 * b ₂ +... + a _iN *b _N , coding coefficient For " _!Ί , <3⁄4,..., °

7. 如权利要求 6所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，所述编码后数据块需将其编码系数 a_i2, ... , a_iN附在其数据的头部、尾部或其它指定位置发送给 DNS 从服务器。 7. The network coding-based adaptive DNS zone file transmission method according to claim 6, wherein the coded data block needs to have its coding coefficients a _i2 , ... , a _iN attached to its data. The header, trailer, or other specified location is sent to the DNS slave.

8.如权利要求 1所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，设区文件译码模块接收到的 W个文件子块为： c ... c'_N], 则这 N个文件子块的编码系数构成的矩阵为：

The network code-based adaptive DNS zone file transmission method according to claim 1, wherein the W file sub-blocks received by the zone file decoding module are: c ... c' _N ], Then the matrix of the coding coefficients of the N file sub-blocks is:

所述 N个文件子块的编码系数 :

Coding coefficients of the N file sub-blocks:

原始数据块 b₂ ... 可由下述方法获得:

The original data block b ₂ ... can be obtained by the following method:

将得到的文件子块 b₂ ... 进行合并后，得到原始 DNS区文件。 After the obtained file sub-blocks b ₂ ... are combined, the original DNS zone file is obtained.

9.如权利要求 1所述的基于网络编码的自适应 DNS区文件传输方法，其特征在于，所述有限域包括 GF (2 -8)。 The network code-based adaptive DNS zone file transmission method according to claim 1, wherein the finite field comprises GF (2 -8).

10.—种基于网络编码的自适应 DNS区文件传输***，其特征在于，包括一个 DNS主服务器，和多个 DNS从服务器，所述 DNS主服务器上加载链路状况监测模块、区文件切分模块、编码系数生成模块以及区文件重编码模块，所述在 DNS从服务器上增加区文件译码模块； 10. An adaptive DNS zone file transmission system based on network coding, comprising: a DNS primary server, and a plurality of DNS slave servers, wherein the link primary monitoring module loads the link status monitoring module and the zone file segmentation a module, a coding coefficient generation module, and a zone file re-encoding module, wherein the zone file decoding module is added to the DNS slave server;

所述载链路状况监测模块，实时检测主从服务器之间的链路状况数据，检测的指标包括丢包率、往返时延；检测得到的链路状况数据进入区文件切分模块和编码系数生成模块；所述区文件切分模块，将原始 DNS区文件切分成若干个文件子块； The link status monitoring module detects link status data between the master and slave servers in real time, and the detected indicators include a packet loss rate and a round trip delay; the detected link status data enters the area file segmentation module and the coding coefficient. Generating a module; the zone file segmentation module, and dividing the original DNS zone file into a plurality of file sub-blocks;

所述编码系数生成模块，将编码后每个数据块附加其编码系数，并传输给 DNS从服务器; 所述区文件重编码模块，将编码后的数据块依次或同时发送给 DNS从服务器， DNS从服务器的区文件译码模块负责接收来自 DNS主服务器区文件重编码模块发送的数据块； The encoding coefficient generating module adds each encoding block to its encoding coefficient and transmits it to the DNS slave server; the zone file re-encoding module sends the encoded data block to the DNS slave server in sequence, or simultaneously. The zone file decoding module of the server is responsible for receiving the data block sent by the file re-encoding module of the DNS main server zone;

所述译码模块，接收从 DNS主服务器的区文件重编码模块传输的编码数据，并对所述编码数据进行译码。 The decoding module receives the encoded data transmitted from the zone file re-encoding module of the DNS master server, and decodes the encoded data.