| 安防监控项目中如何合理选择交换机？ |
| 添加时间：2017/11/28 15:30:54 浏览次数： |
| 随着现在高清视频监控摄像机性能越来越高，在视频监控项目中经常会遇到视频卡顿、丢包一系列的问题，那么如何选择一个适合的监控交换机，既能满足监控系统整体网络的性能要求，又能达到降低成本的目的。 With high-definition video surveillance cameras now increasingly high performance in video surveillance project, often encountered in the video Caton, packet loss in a series of problems, so how to choose a suitable control switch, which can meet the requirement of the performance of the whole network monitoring system, and can reach the purpose of reducing the cost. 我们都知道一个完整的监控网络有三层架构方式：核心层、汇聚层和接入层。 We all know that a complete monitoring network has three layers of Architecture: the core layer, the aggregation layer and the access layer. 那么在选择这些交换机的时候，要考虑那些因素呢？ So when choosing these switches, what are the factors to consider? 交换机的接口数量和速率是选择监控交换机的最重要指标。交换机的接口数量可依据接入设备数量来决定，同时会预留部分接口供后续扩展使用；为保障视频流量无阻塞、不丢包、实时传输，需要选择端口速率合适的交换机，主要考虑以下几点： The number and rate of the interface of the switch are the most important indicators of the selection of monitoring switches. The number of interfaces of switches can be determined according to the number of access devices. At the same time, some interfaces will be reserved for subsequent expansion. In order to protect video traffic from no blocking, no packet loss and real-time transmission, we need to select port rate appropriate switches, mainly considering the following points. 1、 监控交换机的使用带宽与IPC的码流大小密切相关； 1. The bandwidth of the monitoring switch is closely related to the size of the IPC code stream. 2、 IPC的峰值带宽需求=码流×120%，峰值带宽下可以保障IPC稳定使用； 2, the peak bandwidth requirement of IPC = code stream x 120%, and the peak bandwidth can guarantee the stable use of IPC. 3、 NVR添加IPC后，会同时取IPC的主码流和子码流； 3, after adding IPC, NVR will take the main stream and the substream of the IPC at the same time. 4、 交换机的实际带宽建议不超过端口最大速率的70%，即百兆接口不建议超过70M带宽，千兆接口不建议超过700M带宽。 4, the actual bandwidth switch does not exceed the maximum rate of the 70% ports, namely fast interface is not recommended more than 70M bandwidth, Gigabit interface is not recommended more than 700M bandwidth. 快速计算公式：带宽值=（主码流+子码流）*取流路数*1.2 Fast calculation formula: bandwidth = (Ma Liu + Ma Liu) * the flow path of *1.2 IPC的码流与采用的编码方式（H.264或H.265）有关，默认情况下IPC的码流为： The stream of IPC is related to the encoding method used (H.264 or H.265). By default, the stream of IPC is: 我们以1080P摄像机为例来考虑一下接入层交换机的选择： Let's take the 1080P camera as an example to consider the choice of an access layer switch: 条件一： Condition 1: 摄像机码流为4.5Mbps,16个摄像机就是14*4.5=63Mbps，那么，接入层交换机上传端口必须满足峰值带宽需求=码流×120%=63Mbps×120%=75.6Mbps/S的传输速率要求,由上可知交换机实际传输速率(通常为标称值的70%，100M的也就70M左右)，显然是不符合要求的，那么接入层交换机就应选用具有1000M上传端口的交换机。 The camera is 16 4.5Mbps stream, the camera is 14*4.5=63Mbps, then the access layer switch port upload must satisfy the peak bandwidth demand stream transmission rate = * 120%=63Mbps * 120%=75.6Mbps/S, it is the actual transmission rate of the switch (usually a nominal value of 70% 100M is about 70M), obviously does not meet the requirements, then the access layer switch should be used with the 1000M upload port switch. 条件二： Condition two: 交换机的背板带宽：如选择24口交换机，自带二个1000M口，总共26口，则接入层的交换机背板带宽要求为：(24*100M*2+1000*2*2)/1000=8.8Gbps的背板带宽。 The backboard bandwidth of switch is: if 24 switches are chosen, two 1000M ports and 26 ports are needed, the bandwidth requirement of the backboard of the access layer is: the backboard bandwidth of (24*100M*2+1000*2*2) /1000=8.8Gbps. 条件三： Condition three: 包转发率：一个1000M口的包转发率为1.488Mpps/s, 则接入层的交换机交换速率为：24*100M/1000M+2)*1.488=6.55Mpps/S。 Packet forwarding rate: the packet forwarding rate of one 1000M port is 1.488Mpps/s, and the switch exchange rate of the access layer is: 24*100M/1000M+2) *1.488=6.55Mpps/S. 通常我们将满足条件2和3的交换机称之为线速交换机。 The switch that we usually meet the 2 and 3 switches is called a line speed switch. 根据以上条件得出： 当有16路1080摄像机接入一个交换机是，此交换机必须具有1个1000M上传口，16（不含16）个以上的100M接入端口。 According to the above conditions, it is concluded that when there are 16 channels and 1080 cameras to access a switch, the switch must have 1 1000M uploads and 16 (16 or more) 100M access ports. 那么汇聚层交换机及核心交换机也将依次通过计算选择性能满足的交换机。 Then the convergent layer switch and the core switch will also choose the switches that meet the performance in turn. 在监控项目实施的过程中，由于POE交换机的布线方便，传输距离远，也得到更多的选用，其选择也可参考以上计算方法。 In the process of monitoring project implementation, because the POE switch's wiring is convenient and the transmission distance is far away, it also gets more choice. Its choice can also refer to the above calculation method. |
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