HDMI1.4测试解决方案

HDMI以太网通道（HEC）是把以太网集成在HDMI里，避免使用单独的线缆和连接器，减少了制造商成本，简化了用户家庭网络。HDMI1.4规定，HEC采用802.3以太网标准，特别是参照100Base-TX标准，表1列举了HDMI和802.3的几点不同之处。

The HDMI Ethernet Passage (HEC) is an integration of the Ethernet into HDMI, avoiding the use of separate cables and connectors, reducing manufacturer costs and simplifying user home networks. HDMI1.4 states that the HEC applies the Ethernet standard of 802.3 and refers in particular to the 100Base-TX standard, and table 1 lists a number of differences between HDMI and 802.3.

表1  以太网和HDMI HEC的差别

除了物理层的区别以外，在以太网的方式使用通道之前，HEC需要一个初始化过程，这个初始化过程叫做能力发现和控制（CDC，Cpability Discovery and Control）HEC设备必须通过符合协议规范的测试，本文主要介绍HDMI-HEC技术和测试需求。

In addition to the differences in the physical layer, the HEC needs an initialization process called Capability Identification and Control (CDC, Capability Discovery and Control) HEC equipment to pass protocol-compliant tests prior to using the channel in a hypernetic way, which is described in this paper primarily as the technical and test needs of HDMI-HEC.

2  HDMI-HEC基础技术

2  HDMI-HEC Basic Technology

2.1  解决环路问题

2.1 & nbsp; Solving loop problems

为了解决网络环路问题，HDMI1.4借鉴了最小生成树协议STP（Spanning Tee Protocol）来解决此问题。最小生成树简化网络拓扑，形成树状拓扑，因此从网络中的一个节点到另外任何一个节点都只有一条途径。图2为最简单的HEC网络，构成一个最基本的最小生成树。

In order to solve the problem of network loops, HDMI1.4 draws on the Minimum Generation Tree Protocol STP (Spanning Tee Protocol) to solve the problem. The Minimum Generation Tree Simplified Network Top, which forms a tree top, has only one route from one node in the network to any other node. Figure 2 is the simplest HEC network, constituting a minimum generation tree.

图2  最基本的最小生成树

如果网络节点a成为根节点，就需要去使能节点b和节点c之间的链路，消除潜在的网络环路。网络之间的节点通信是用STP协议，或RSTP协议（Rpid Sanning Tee Potocol）。IEEE802.1w定义了RSTP协议，它是对原有STP的一个改进，减少了聚敛时间，STP的聚敛时间是30~0s，STP的聚敛时间只有6s。RSTP节点之间的通信是使3桥协议数据单元BPDU（Uses Bridge Protocol Data Units），当某条链路出现故障，RSTP可以把一条去使能的链路转变为转发模式，使整网的各节点可达。如图3所示，如果节点a和节点c之间的链路出现故障，将使能节点b和节点c之间的链路。

If network nodea becomes a root node, it is necessary to make the link between energy nodeb and node c and eliminate potential network loops. The node communication between networks is using the STP protocol, or RSTP protocol (Rpid Sanning Tee Potocol). IEE802.1w defines the RSTP protocol, which is an improvement on the original STP and reduces the concentration time, and STP's time of convergence is only 6 s. The communication between RSTP node node is a link between the three bridge node data unit BPDU (Us Bridge Protocol Data Unit) and the energy node b and node c, when there is a malfunction, RSTP can turn an energy link into a forwarding mode, making the entire network accessible. As shown in Figure 3, if there is a break in the chain between node a and node c, the communication between RSTP node node is a link between the energy node b and node c.

图3  最小生成树发现过程

HDMI1.4测试规范要求HDMI设备可以在HEC上正确转发BPDU帧，用RSTP协议取消网络环路。

The HDMI 1.4 test specifications require that the HDMI device be correctly forwarded to the BPDU frame on HEC and that the network loop be cancelled using the RSTP protocol.

2.2  队列控制 （Queue Control）

2.2  Queue Control

希望HEC网络中的设备可以区分流量的优先级，对时间敏感的应用流量，例如在线游戏，视频，VoIP应该比文件下载的流量的优先级高。在HEC网络，通过使用VALN（Virtual Lcal Aea Ntwork）区分流量优先级。图4和图5说明了这个过程。

It is hoped that equipment in the HEC network will distinguish between traffic priorities and time-sensitive applications, such as online games, videos, and VoIPs, which should be higher than the flow of document downloads. In the HEC network, the process is illustrated by the use of VALN (Valtual Lcal Aea Ntwork).

图4  插入了VLAN TAG的以太网帧

图5  VLAN TAG的结构

HEC规范规定在网络里至少支持4个队列。我们需要测试用VLAN TAG区分不同流量的优先级，并确保HEC设备在网络发生拥塞时，不丢失高优先级的流量。进一步的测试还需要验证VLAN TAG值通过HEC网络是不变化的。

HEC norms require that at least four queues be supported in the network. We need to test VLAN TAG to distinguish between different traffic priorities and to ensure that HEC equipment does not lose high-priority traffic in the event of network congestion. Further tests also need to verify that VLAN TAG values do not change through the HEC network.

2.3  流行的网络技术

2.3 & nbsp; popular network technology

HEC之所以重要和流行，是因为它在家庭网络中具有竞争优势。第一是被机顶盒生产厂商、游戏提供商和集中多媒体的PC提供商所推动，可以在这些设备上提供互联网终端。第二是被电视生产厂商推动，他们在不断寻求新的功能。一个明显的机会是在电视范围内增加全面的网络功能，提供全面的网络能力，例如统一即插即用UPnP（Universal Plug and Play）、数字生活网络联盟DLNA（Digital Living Network Alliance）和LiquidHD。

HEC is important and popular because it has a competitive advantage in the family network. The first is driven by top box producers, game providers and central multimedia PC providers, which can provide Internet terminals on these devices. The second is driven by television producers, who are constantly seeking new functions. A clear opportunity is to add a full network function to the television, providing a comprehensive network capability, such as UPnP (Universal Plug and Play), Digital Life Network Alliance (DLNA) and LiquidHD.

UPnP是一套完整的协议，使家庭网络中的设备可以无缝相互连接。UPnP协议包括6个重要功能：寻址、发现、描述、控制、事件触发和展示。

The UPnP protocol includes six important functions: location, discovery, description, control, event triggering and presentation.

DLNA即在家庭内外建立一个集中管理个人电脑（PC）、家电（CE）和移动电子设备的互操作性网络，创造一个能够共享和发展全新数字媒体和内容服务的无缝环境。DLNA标准定义了四种主要的产品类型，即Digital Media Server（DMS），Digital Media Player（DMP），Digital MediaController（DMC）和Digital Media Printer（DMPr）。

DLNA defines four main product types, namely, Digital Media Server (DMS), Digital Media Player (DMP), Digital MediaController (DMC) and Digital Media Printer (DMPr).

LiquidHD这项新型个人娱乐技术可将电视、消费电子设备、个人电脑、便携媒体设备以及家庭影院快速、简便地连接成一个无缝网络，让身处网络中的消费者能在家里任何一台采用LiquidHD技术的显示器上尽享任何一个来源设备上的数字内容。目前，消费者只能在电视上观看多媒体内容，数码摄像机、机顶盒、DVD/蓝光光盘（Blu-ray Disc?）播放器或游戏机与电视直接相连。有了LiquidHD技术，消费者能够在家里随心所欲地观看，他们可以先暂停客厅电视上正在播放的电影、电视节目或视频游戏，然后按一下遥控器按钮，就可以在另一台电视或笔记本电脑上接着观看。LiquidHD可以使用各种物理介质，其中包括HDMI，Ethernet，同轴电缆和输电线。

LiquidHD, a new personal entertainment technology, allows television, consumer electronics, personal computers, portable media equipment, and home cinemas to be connected quickly and easily to a seamless network that allows consumers in the network to enjoy any of the digital content from any source on any display that uses LiquidHD technology at home. Currently, consumers can only watch multimedia content on television, digital cameras, machine top boxes, DVD/blue discs (Blu-ray Disc?) players or video players directly connected to television. With LiquidHD technology, consumers can view movies, television programmes or video games that they are playing on television in the living room, and then press the remote control button, which allows them to watch on another television or laptop. LiquidHD can use a variety of physical media, including HDMI, Ethenet, cable and transmission lines.

3  IXIA HDMI测试解决方案

3 IXA HDMI test solution

HDMI协议标准是由技术创始厂家（Sony，Phillips，Silicon Image，Panasonic，Hitachi，Thomson and Toshiba）研发出来的，这些创始厂家建立了授权测试中心ATC（Authorized Testing Centers），生产厂家必须通过认证测试才能使用HDMI标志。全世界有7个授权测试中心ATC，它们分别分布在Sony（日本），Panasonic（日本），Phillips（印度和法国），Silicon Image（中国（2个ATC）和美国）。

The HDMI protocol standards were developed by technology founders (Sony, Phillips, Silicon Image, Panasonic, Hitachi, Thomson and Toshiba), who set up the Authorized Test Centre ATC, where producers had to pass certification tests to use the HDMI logo. There are seven authorized testing centres ATC worldwide, distributed in Sony (Japan), Panasonic (Japan), Phillips (India and France), Silicon Image (China (2) and the United States).

生产厂家必须按照测试标准CTS（Compliance Test Specification）进行测试，然后提交到ATC做协议一致性测试。IXIA与Sony公司合作，制定了CTS标准，在CTS中IxN2X是测试以太网通道（HEC）的惟一测试设备。IxN2X执行测试例来验证CTS，测试场景如下：

Producers must test the CTS in accordance with the test standard CTS (Completion Test System) and then submit it to ATC for protocol consistency testing. IXIA, in collaboration with Sony, has developed the CTS standard. In CTS, IxN2X is the only test facility to test the Ethernet Channel (HEC). IxN2X implements test cases to validate the CTS, as follows:

（1）Packet Filtering/Forwarding。
　　（2）Forwarding of BPDU。
　　（3）RSTP Functionality。
　　（4）Queue Control。
　　（5）Unchanged Priority Tag Value。

 IxN2X测试环境配置如图6所示。

The & nbsp; IxN2X test environment is configured as shown in Figure 6.

图6  IxN2X测试环境配置

IxN2X提供转换器（见图7）一端是HDMI接口，一端是以太网接口。HDMI的初始过程可以通过外置的CEC/CDC控制器或借助可选的EEPROM实现，SPDIF同时使能音频回传通道（与HDMI信号的方向相反）。

IxN2X provides a converter (see figure 7) at the end of which the HDMI interface is located on the other end. The initial process of HDMI can be achieved either through an external CEC/CDC controller or through an optional EEPROM, while SPDIF enables audio loops (in contrast to the direction of the HDMI signal).

图7  IxN2X HDMI转换器

以包过滤和转发测试为例，介绍HDMI CTS测试过程，测试配置和测试流程可参考图8所示。测试步骤如下：

The HDMI CTS test process is presented as an example of a package filtering and forwarding test, and the test configuration and testing process can be referenced in figure 8. The test steps are as follows:

图8  包过滤和转发测试

●连接和配置测试端口。
　　●以很高的流量速率，从所有端口同时发送1s流量，向过滤数据库注册源MAC地址；
　　●以100，000frames/s的速率从所有端口发送10×106个64字节长度的包。Port1向Port2发包；Port2向Port3发包；Port3向Port1发包。
　　●在所有测试端口统计接收的包数。
　　●在测试端口1，按以下规则验证。其中，criteria #1=100 assuming 10×10-6packet error rate；criteria #2=2。
　　——在port3上接收的包数-从port3上发送的报数≤criteria #1。
　　——在Port2上接收的包数≤criteria #2。
　　——在Port1上接收的包数≤criteria #2。
　　●如果DUT的端口数＞3个，可以轮流使用3个测试端口测试。
　　●如果所有测试都通过，则此测试成功。

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4  结束语

4  final remarks

对于家庭网络，HEC是新兴的发展方向，具有很大的发展潜力。在HDMI1.4 CTS（Compliance Test Specification）中，IXIA IxN2X作为惟一被推荐的测试仪表，可用于HDMI以太网网络的测试。
 

HEC is an emerging and promising development for family networks. In HDMI1.4 CTS, IXIA IxN2X is the only recommended test instrument that can be used to test the HDMI web network.
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