Multicasting Overview

Transcription

1 Multicasting Overview Application Note Pleora products can be used in both unicast and multicast modes. In unicast mode, images are transmitted from a GigE Vision transmitter to a single GigE Vision receiver. In multicast mode, a GigE switch replicates traffic to multiple subscribed GigE Vision receivers. GigE Vision Receiver. A device that receives GigE Vision images and related data over Gigabit Ethernet (GigE). A receiver can be a vdisplay HDI-Pro IP engine, GEVPlayer, NetCommand, or any other GigE Vision compliant receiver created with the Pleora ebus SDK. GigE Vision Transmitter. A video and control interface that transmits images and related data over Gigabit Ethernet. A transmitter can be a Pleora iport IP engine, such as an iport Analog-Pro IP engine, or a GigE Vision compatible camera. The following topics are covered in this application note: How Multicasting Works on page 2 Multicasting Example on page 3 Configuring Your Switch for Multicasting on page 4 Sample Applications on page 5

2 How Multicasting Works Multicasting is a method of sending data to a group of interested receivers simultaneously, in a single transmission, from a given source. Over Internet Protocol version 4 (IPv4), sources (such as GigE Vision transmitters) and receivers (such as GigE Vision receivers) use multicast group addresses and ports to send and receive multicast messages. IPv4 addresses between and (class D) are designated as multicast group addresses. Sources use a multicast group address and port as the destination IP address and port for the data, while receivers use this group address to inform the network that they are interested in receiving data from the multicast group. In a GigE Vision environment, an application running as a controller configures the GigE Vision transmitter to send an image stream to a multicast group administered by an Internet Group Management Protocol (IGMP) v2-capable Gigabit Ethernet switch. GigE Vision receivers can then subscribe to the multicast group and receive the image stream. GigE Vision Transmitter Transmitting to a multicast group IGMP Switch Video Processing and Display Applications Receiving from a multicast group GigE Vision Receiver Receiving from a multicast group Display monitor Application Running as a Controller For examples of other multicasting scenarios, see the following guides, which are available on the Pleora Technologies Support Center: vdisplay HDI-Pro IP Engine User Guide. Multicasting scenario with a camera in which the vdisplay HDI-Pro IP engine acts as a controller and a receiver. Video Server API Quick Start Guide. Multicasting scenario in which the Video Server API transmits to a multicast address. EX Version 1.0 Multicasting Overview Page 2

3 Multicasting Example In a medical implementation, an image stream is captured by an imager within a fluoroscope, for example during an angioplasty operation, and then transmitted to an iport IP engine. The stream is then multicast over a Gigabit Ethernet network to a storage computer and a computer that is used for display and configuration in the control room. The image stream is also sent to a software-based video processing unit that creates a new composite image stream one that highlights areas of interest, includes pre-op images, and shows vital signs. This composite stream can be sent to a video receiver, such as a vdisplay HDI-Pro IP engine, which in the diagram is attached to the monitor in the operating room. This example shows one (of many) possible implementations of multicasting image streams in a medical environment. EX Version 1.0 Multicasting Overview Page 3

4 Configuring Your Switch for Multicasting When the switch receives multicast packets, it forwards them to all network segments that have one or more subscribers for the specified multicast group. To determine which network segments have subscribers for the multicast group and should receive the transmitted images, the switch uses IGMP snooping. By using this approach, the bandwidth, traffic, and server loads are reduced because images are only transmitted to the appropriate network segments. Some switches have appropriate default settings for IGMP snooping that ensure multicast traffic is delivered correctly, while other switches must be configured explicitly to enable IGMP snooping. Some switches do not have the option to disable IGMP snooping (this feature is always on). EX Version 1.0 Multicasting Overview Page 4

5 Sample Applications The ebus SDK has two sample applications that work together to connect to a GigE Vision device, initiate a multicast stream, and subscribe to the stream. For information about using these samples, see the Video Server API Quick Start Guide and the ebus SDK Programmer s Guide, which are available on the Pleora Technologies Support Center. The sample code listed in the following table is available for both C#.NET and C++. Table 1: Sample Code Sample code PvMulticastMasterSample PvMulticastSlaveSample Function Connects to a GigE Vision device and initiates a multicast stream (by default it transmits to , port 1042).* This sample code is used in conjunction with the PvMulticastSlaveSample, which subscribes to the multicast stream. Receives an image stream as a multicast slave from a multicast master.* This sample is used in conjunction with the PvMulticastMasterSample, which initiates the multicast stream. Type of application that is created UI-based for C#.NET. Command line for C++. UI-based for C#.NET. Command line for C++. * This sample requires a switch that supports IGMP v2. EX Version 1.0 Multicasting Overview Page 5

6 Technical Support On the Pleora Support Center, you can: Download the latest software. Log a support issue. View documentation for current and past releases. Browse for solutions to problems other customers have encountered. Get presentations and application notes. Get the latest news and information about our products. Decide which of Pleora s products work best for you. To visit the Pleora Support Center Go to and click Support Center. If you have not registered yet, you are prompted to register. Accounts are usually validated within one business day. If you have difficulty finding an existing solution in the knowledge base, post a question by clicking Log a Case. Provide as many specific details about your system and the nature of the issue as possible. Copyright Information Copyright 2012 Pleora Technologies Inc. These products are not intended for use in life support appliances, devices, or systems where malfunction of these products can reasonably be expected to result in personal injury. Pleora Technologies Inc. (Pleora) customers using or selling these products for use in such applications do so at their own risk and agree to indemnify Pleora for any damages resulting from such improper use or sale. Trademarks PureGEV, ebus, iport, vdisplay, and all product logos are trademarks of Pleora Technologies. Third party copyrights and trademarks are the property of their respective owners. Notice of Rights All information provided in this manual is believed to be accurate and reliable. No responsibility is assumed by Pleora for its use. Pleora reserves the right to make changes to this information without notice. Redistribution of this manual in whole or in part, by any means, is prohibited without obtaining prior permission from Pleora. Document Number EX Version 1.0 EX Version 1.0 Multicasting Overview Page 6