可堆叠VLAN在城域网中应用的研究
摘要
近年来，通信网络进行了非常大的变化，以电路交换为主的传统电信运营网络与以数据业务为主的计算机网络进行了业务和网络的融合。但是，随着新的城域网的产生，以往的对VLAN中VID字节宽度的定义限制了网络VLAN的数目，为此，各家网络设备制造商采用了不同的方法来扩充VLAN ID的数目。
随之而来的是用户量的快速增长将突破以前的局域网的规范，VLAN ID的资源不能满足接入层的要求，同时高带宽、高质量的传送网络，提供了新的VLAN解决方案。
本文采用的一种自定义的可堆叠VLAN技术，在不改变用户VLAN ID的情况下，利用增加6个字节的可堆叠VLAN(SVLAN)字段，在用户端口处进行自定义协议的解释，同时完成用户端口汇聚和系统侧端口资源合理有效的利用。本文很好的解决了VLAN中VID数目的问题，而且还达到用户端口汇聚等功能，在提供一个比较好的解决现代城域网中网络急剧扩大所产生的VID资源不足问题上具有现实有效的意义。
软件设计上参考了相关的IEEE标准，系统地进行了数据结构的定义和程序流程的设计，并且使用了主流的嵌入式实时操作系统VxWorks加以实现。
硬件设计上使用强大硬件资源的网络处理器IXP1200进行设计，保证协议处理的快速准确，利用网络处理器的微码资源和微码编程技术，充分发挥了网络处理器的优势和特点。最后，完成了具有支持可堆叠VLAN功能的交换机，并进行了长、短帧的测试。
测试结果表明：在增加了堆叠VLAN(SVLAN)字段后，对2层交换线速交换没有任何影响，对用户的VID资源保护的很好，汇聚功能能够实现。为可堆叠VLAN在以太网中的广泛应用提供了有价值的参考。
Communication network has been changed greatly in recent years, and the telecom network based on circuit switch is combined with computer network based on data services in the service and network field. However, the number of VLAN is limited by the definition for the byte width of VID in VLAN with the development of the MAN. Therefore, many manufactures of network equipment try their best to expend the number of VLAN in different ways.
The resource of VLAN ID can not satisfied with the demand of the access layer because of the dramatic increase of users. However, it can be solved by using transmission network with high bandwidth and high quality.
A user-defined stackable VLAN is presented in this paper. It can complete the truck of user port and use the resource of system side port reasonably and efficiently without changing users' VLAN IDs, by adding six-bytes long SVLAN to explain the user-defined protocol. The way presented here can not only solve the problem on the number of VID in VLAN, but also fulfill the truck of the user port. That is very meaningful in solving the problem caused by the deficient resource of VID for rapid spread in the network of MAN.
Data structure is defined and the flow of program is designed, according to the IEEE standard, and the VxWorks, which is the mainstream real time embedded operating system, is used in software design.
The powerful net processor IXP 1200 is used in hardware design, which can make the procession of protocol quick and accurate. Moreover, both programming techniques on microcodes and network processor microcodes are applied successfully, which uses the advantage and characteristic of network processor sufficiently. In the meantime, the switch based on stackable VLAN is put into practice, and test for long and short frames is performed.
The results of test show: the truck is realizable after adding the field of SVLAN. Meanwhile, the thread rate of layer 2 isn't influenced and the resource of user VID is protected well. That demonstrates potential applications of the stackable VLAN in Ethernet.
随之而来的是用户量的快速增长将突破以前的局域网的规范，VLAN ID的资源不能满足接入层的要求，同时高带宽、高质量的传送网络，提供了新的VLAN解决方案。
本文采用的一种自定义的可堆叠VLAN技术，在不改变用户VLAN ID的情况下，利用增加6个字节的可堆叠VLAN(SVLAN)字段，在用户端口处进行自定义协议的解释，同时完成用户端口汇聚和系统侧端口资源合理有效的利用。本文很好的解决了VLAN中VID数目的问题，而且还达到用户端口汇聚等功能，在提供一个比较好的解决现代城域网中网络急剧扩大所产生的VID资源不足问题上具有现实有效的意义。
软件设计上参考了相关的IEEE标准，系统地进行了数据结构的定义和程序流程的设计，并且使用了主流的嵌入式实时操作系统VxWorks加以实现。
硬件设计上使用强大硬件资源的网络处理器IXP1200进行设计，保证协议处理的快速准确，利用网络处理器的微码资源和微码编程技术，充分发挥了网络处理器的优势和特点。最后，完成了具有支持可堆叠VLAN功能的交换机，并进行了长、短帧的测试。
测试结果表明：在增加了堆叠VLAN(SVLAN)字段后，对2层交换线速交换没有任何影响，对用户的VID资源保护的很好，汇聚功能能够实现。为可堆叠VLAN在以太网中的广泛应用提供了有价值的参考。
Communication network has been changed greatly in recent years, and the telecom network based on circuit switch is combined with computer network based on data services in the service and network field. However, the number of VLAN is limited by the definition for the byte width of VID in VLAN with the development of the MAN. Therefore, many manufactures of network equipment try their best to expend the number of VLAN in different ways.
The resource of VLAN ID can not satisfied with the demand of the access layer because of the dramatic increase of users. However, it can be solved by using transmission network with high bandwidth and high quality.
A user-defined stackable VLAN is presented in this paper. It can complete the truck of user port and use the resource of system side port reasonably and efficiently without changing users' VLAN IDs, by adding six-bytes long SVLAN to explain the user-defined protocol. The way presented here can not only solve the problem on the number of VID in VLAN, but also fulfill the truck of the user port. That is very meaningful in solving the problem caused by the deficient resource of VID for rapid spread in the network of MAN.
Data structure is defined and the flow of program is designed, according to the IEEE standard, and the VxWorks, which is the mainstream real time embedded operating system, is used in software design.
The powerful net processor IXP 1200 is used in hardware design, which can make the procession of protocol quick and accurate. Moreover, both programming techniques on microcodes and network processor microcodes are applied successfully, which uses the advantage and characteristic of network processor sufficiently. In the meantime, the switch based on stackable VLAN is put into practice, and test for long and short frames is performed.
The results of test show: the truck is realizable after adding the field of SVLAN. Meanwhile, the thread rate of layer 2 isn't influenced and the resource of user VID is protected well. That demonstrates potential applications of the stackable VLAN in Ethernet.
引文
[1]《现代通信》浅谈VLAN技术2002年第11期p6～p8
[2]交换机技术 http://bluestudy1998.nease.net/fasj/campus/jiaohuanjs/htm
[3]《VLAN技术白皮书》 华为公司 p3
[4]《VLAN技术白皮书》 华为公司 p3
[5]《VLAN技术白皮书》 华为公司 p4
[6]《VLAN技术白皮书》 华为公司 p4
[7]《VLAN技术白皮书》 华为公司 p4
[8]《VLAN技术白皮书》 华为公司 p4
[9]《VLAN技术白皮书》 华为公司 p5
[10]http://www.networkunion.org/suject/vpdn/vpn_intr.htm 虚拟网技术概述 尚久济 尚世雄
[11]《城域光网络》 人民邮电出版社 徐荣 龚倩等 p72～p74
[12]《城域光网络》 人民邮电出版社 徐荣 龚倩等
[13]《城域光网络》 人民邮电出版社 徐荣 龚倩等
[14]易龙 人民邮电报 http://www.cnii.com.cn/20020808/ca78101.htm
[15]城域网中的以太网应用 http://www.gog.com.cn/jqpd/pd02001/ca246714.htm
[16]L2TPv3-Introduced at IETF 51 (London) August 2001-draft-ietf-12tpext-12tp-base-00.txt
[17]思科城域以太网接入业务控制平面设计指南
[18]Lassere, Transparent VLAN Services over MPhS-draft-lasserre-tls-mpls-00.txt
[19]《IXP1200 HW Ref Manual》 p31
[20]《IXP1200 Datasheet》 p58
[21]《千兆比以太网交换机设备技术规范送审稿》 p16
[2]交换机技术 http://bluestudy1998.nease.net/fasj/campus/jiaohuanjs/htm
[3]《VLAN技术白皮书》 华为公司 p3
[4]《VLAN技术白皮书》 华为公司 p3
[5]《VLAN技术白皮书》 华为公司 p4
[6]《VLAN技术白皮书》 华为公司 p4
[7]《VLAN技术白皮书》 华为公司 p4
[8]《VLAN技术白皮书》 华为公司 p4
[9]《VLAN技术白皮书》 华为公司 p5
[10]http://www.networkunion.org/suject/vpdn/vpn_intr.htm 虚拟网技术概述 尚久济 尚世雄
[11]《城域光网络》 人民邮电出版社 徐荣 龚倩等 p72～p74
[12]《城域光网络》 人民邮电出版社 徐荣 龚倩等
[13]《城域光网络》 人民邮电出版社 徐荣 龚倩等
[14]易龙 人民邮电报 http://www.cnii.com.cn/20020808/ca78101.htm
[15]城域网中的以太网应用 http://www.gog.com.cn/jqpd/pd02001/ca246714.htm
[16]L2TPv3-Introduced at IETF 51 (London) August 2001-draft-ietf-12tpext-12tp-base-00.txt
[17]思科城域以太网接入业务控制平面设计指南
[18]Lassere, Transparent VLAN Services over MPhS-draft-lasserre-tls-mpls-00.txt
[19]《IXP1200 HW Ref Manual》 p31
[20]《IXP1200 Datasheet》 p58
[21]《千兆比以太网交换机设备技术规范送审稿》 p16