Digital Video Solution for Multiple Viewers i MPath N e t w o r k s Multicast Solution How does it work ? Hit left mouse key, the Enter key or Page Up or Down to advance to the next slide July 2005 version 3

i MPath N e t w o r k s Note to Viewer The content of this tutorial provides an overview of IGMP used in Digital Multicast networks to familiarize customers with the technology. The information in this document is subject to change without notifice. While every precaution was taken in the preparation of this document, iMPath assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. Should you have any questions, please feel free to contact: Daniel Brisson Sr. System Engineer iMPath Networks Inc Tel: x Gilles Lebel Sr. System Engineer iMPath Networks Inc Tel: x

i MPath N e t w o r k s Typical Network Requirements Backbone Monitor any video from anywhere in the network

i MPath N e t w o r k s Multicast Multicast. Allows sending one copy of each packet to the group of computers that want to receive it. Multicast can be implemented at the Ethernet link- layer or at the network layer (layer 3 of the OSI model). Computers join and leave multicast groups by using the IGMP (Internet Group Management Protocol) Each host can register itself as a member of selected multicast groups through use of the Internet Group Management Protocol (IGMP). Multicast is commonly used in audio and video streaming applications. –It allows a single source of traffic to be viewed by multiple destinations simultaneously. –It is designed to provide an efficient transmission using the least amount of bandwidth on the network to save cost. IGMP is a standard IP protocol supported by most LAN/WAN vendors in traditional LAN products, ATM, and gigabit Ethernet solutions.

i MPath N e t w o r k s 100 Meg Typical Network Components Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L3 Switch/Router L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network Typical high speed backbone network consisting of Layer 2 or Layer 3 Ethernet Switches. High Speed Switches are located at major hub locations to collect or drop off data traffic from this distribution center. Field hub locations are distributed where the end devices are located. They are used to collect and distribute traffic for Cameras, Traffic Controllers, Message Signs and many more. Several topologies can be used such as Star and Linear topologies being the most common. 100 Meg

i MPath N e t w o r k s 100 Meg Typical Network Components Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L3 Switch/Router L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network The Control Centers provide video viewing and control of the Camera PTZ, Traffic Controllers, or Message signs to name just a few. 100 Meg Multiple Control Centers may be deployed with this architecture. The Virtual Matrix is commonly used in digital video networks providing video display and control and to operate complementary integrated applications.

i MPath N e t w o r k s 100 Meg Why use IGMP? Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network 100 Meg Without IGMP support, multicast traffic is transmitted to all the ports in each network switch. This unnecessary traffic floods the interfaces and can quickly bog down the entire network.

i MPath N e t w o r k s 100Base-T Why use IGMP? Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network 100Base-T For example: With 25 cameras deployed, each transmitting at 5 Mbps, you will have over 125 Mbps of combined traffic on your network 125 Mbps of traffic on each 100Base-X interface !!!!!! 125 Mbps of traffic 100Base-T

i MPath N e t w o r k s Why use IGMP? Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network On a 100 Mbps interface (optics or electrical) you cannot pass more then 100 Mbps of traffic. PROBLEM Combined 125 Mbps of traffic on these interfaces. The capacity of this network is exceeded with only 25 cameras In fact a typical recommendation in the industry is not to exceed 70% of the bandwidth in any segment. For example: With 25 cameras deployed, each transmitting at 5 Mbps, you will have over 125 Mbps of traffic on your network 100Base-T

i MPath N e t w o r k s Traffic flow with IGMP Decoder Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Decoder L2 Switch Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 2Control Center # 1Typical field encoder collector network 100Base-T 100 Meg Only 15 Mbps of multicast traffic flows on this link Only 5 Mbps of Multicast traffic Flows on this port Traffic is only present on the backbone when a decoder requests the specific encoder stream Video Stream 1 Video Stream 2 Video Stream 3 100Base-T

i MPath N e t w o r k s How does it work? Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L3 Switch/Router Encoder Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 1Typical field encoder collector network 100 Meg The Encoder is considered a “server” in the IGMP world. It generates a video signal that will be made available to any Decoder (client) on the network. The Encoder transmits a signal with a distinct destination address. Between 224.x.x.x to 239.x.x.x. (some addresses are reserved for specific applications) The Routers build and share a table of all the “IGMP servers” available on the network. They keep a table of all the available Multicast Addresses This Router will not forward any of the multicast traffic until it receives a request from a decoder (client)

i MPath N e t w o r k s Here is how it works - Joining a Group Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L3 Switch/Router Encoder Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 1Typical field encoder collector network 100 Meg The operator makes a request to see a video on a specific monitor The Virtual Matrix application forwards a message to the decoder to view a specific video stream. (request to see video from address ) The Decoder registers this address in its table and forwards the request (join the multicast group) to the network The Router responds and forwards the traffic to this specific port on the Ethernet switch

i MPath N e t w o r k s Digital Backbone; ATM, SONET, LAN, Gigabit Ethernet... L3 Switch/Router Encoder Decoder Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 1Typical field encoder collector network 100 Meg When the operator makes a request to change the view from video A to video B… … the Virtual Matrix application ONLY forwards a single message to the decoder to view video B stream. (request to see video from address ) The Decoder un-registers from the present viewing address (a “leave” message is sent) followed by a “join” message which is sent with the new multicast stream. Encoder Video AVideo B The Router stops video stream A, adds the new video B to the group, and releases the traffic for video B to this specific port on the Ethernet switch Here is how it works - Leaving a Group

i MPath N e t w o r k s Choosing your network elements There are several types of digital network technologies to choose from. –SONET and ATM are still applicable but are now rarely deployed on new installations. –Ethernet is the most common technology due to the wide range of affordable products available from many manufacturers and the familiarity with Ethernet and IP technology. –The components more commonly used to build Ethernet networks are Ethernet Switches. –A high capacity Ethernet network is often referred to as the “backbone” network.

i MPath N e t w o r k s Choosing your network switches Choosing Ethernet Switches for your backbone network could depend on several factors… –Your specific port density requirements –Network topology –Temperature hardened requirements (outdoor) –Support for IGMP protocol –Your preferred manufacturer –Specific product functionality This tutorial will explore a few topologies and the IGMP functionality of different Ethernet Switches.

i MPath N e t w o r k s Ethernet Switch selection There are 3 types of Ethernet Switches –Layer 2 Switch Distributes traffic to each destination using MAC addressing table. Broadcasts the Multicast traffic across all its ports –There are no Multicast traffic filters with these switches –Layer 2 Switch with IGMP Snooping Distributes traffic to each destination using MAC addressing table Provides limited control of Multicast traffic to prevent broadcast of the traffic to all ports. Layer 3 IGMP master is needed in the network –Layer 3 Switch/Router with IGMP Distributes traffic to each destination using MAC addressing table. Distributes traffic to each destination using IP subnet addressing table. Provides maximum control of Multicast traffic to prevent broadcast of the traffic to all ports and all subnet.

i MPath N e t w o r k s Layer 2 Switch Functionality L2 Switch Encoder L2 Switch Decoder Encoder 5 Mbps 15 Mbps 5 Mbps 15 Mbps 5 Mbps 15 Mbps 5 Mbps 15 Mbps0 Mbps 20 Mbps 0 Mbps 20 Mbps The combined Multicast Traffic is sent to all ports in each Switch This is a valid network topology for small networks Ensure no more then 70% of the bandwidth of the lowest negotiated Ethernet port speed is used. Not to be used with 10 Meg Half Duplex devices. Bandwidth Restriction applies. Combined 20 Mbps Multicast Video Traffic 5 Mbps Multicast Video per Encoder 20 Mbps

i MPath N e t w o r k s Layer 3 Switch/Router with IGMP Functionality L3 Switch Encoder L3 Switch Decoder Encoder 5 Meg Multicast traffic is filtered out at each switch Only the required traffic is transmitted on the network This is a valid network topology for any network - No topology restrictions 10 Mbps Deploying a Layer 3 at each collector HUB could be expensive 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps Combined 10 Mbps Multicast Video Traffic 5 Mbps

i MPath N e t w o r k s Layer 2 & 3 Switch Typical Topology Decoder 0 Mbps 5 Mbps 0 Mbps L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder The L3 Switch controls all Multicast traffic. In and out. It eliminates transmitting the combined multicast traffic unnecessarily to each port. 0 Mbps L3 Switch The use of L2 Switch in this topology is very common. Multicast traffic is repeated on all ports of the switch within the segment but traffic from other segments is not seen. Traffic between the segments is controlled by the L3 switch. Economical and practical solution that is very easy to deploy. 35 Mbps Combined Multicast Video 5 Mbps

i MPath N e t w o r k s Layer 2 & 3 Switch Typical Topology – Industry concern Decoder 0 Meg 5 Meg 0 Meg 5 Meg L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder 35 Mbps 0 Mbps L3 Switch This solution is very effective and greatly simplifies Network Management. However, it is sometimes necessary to filter IGMP traffic at the edge. Such solutions were previously overlooked for economical reasons. An economical solution now exist: L2 switch with IGMP Snooping

i MPath N e t w o r k s Overview of OSI Model Application Presentation Session Transport Network Data Link Physical Layer 7. Layer 6 Layer 5 Layer 4 Layer 3- This layer defines the addressing and routing structure of the Inter-network This layer controls the Multicast traffic on the network. Layer 2- This layer defines the framing, addressing and error control of Ethernet packets. Port addressing uses MAC address of each device. This layer effectively treats Multicast traffic as broadcast traffic. Layer 1 Traditionally performed by Routers Performed by Switches $ $

i MPath N e t w o r k s Overview of OSI Model Network Data Link $ $ New product introduced $ Layer 2 with IGMP Snooping- Layer 2 Switches with IGMP Snooping functionality are now available. Provide all the functionality of a Layer 2 switch with PARTIAL IGMP support. This layer provides some Multicast traffic control on the network. This product can be used instead of expensive Routers Available with different port densities. 100Base-Fx to Gigabit trunks. Temperature Hardened Wide choice of manufacturers and products. Layer 3- This layer defines the addressing and routing structure of the Inter-network This layer controls the Multicast traffic on the network. Layer 2- This layer defines the framing, addressing and error control of Ethernet packets. Port addressing uses MAC address of each device. This layer effectively treats Multicast traffic as broadcast traffic.

i MPath N e t w o r k s Layer 2 Switch with IGMP Snooping Functionality L2 with IGMP Snooping Encoder L3 Switch Decoder Encoder Valid network topology for any network No topology restrictions Local traffic is filtered out at each switch. Eliminates multicasts traffic to all the ports All the multicast traffic is sent to the central site. The L3 switch still controls the IGMP table of the network. 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps 5 Mbps 0 Mbps 20 Mbps Combined Multicast Video

i MPath N e t w o r k s L2 with Snooping & L3 Switch Typical Topology Decoder 0 Mbps 5 Mbps 0 Mbps 5 Mbps L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder These links contain the combined Multicast traffic from all the Encoders in their segment i.e. 35 Mbps. L3 Switch Very practical implementation Management of the Ethernet Switches is required. Switches with IGMP Snooping eliminate flooding local interfaces with Multicast traffic. Bandwidth Restriction applies. No more “70% of link capacity” 35 Mbps

i MPath N e t w o r k s How does it work? From the Encoder to the L3 Switch Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder The L3 Switch forwards the IGMP Query on all its ports to determine if there are any devices that wish to subscribe to a Multicast Group. 0 Mbps L3 Switch Each Encoder forwards a constant Multicast stream to the Ethernet Switch ( x.x.x) The L2 Switch detects/identifies the Multicast stream source and logs internally what port this stream came from. The L2 Switch with IGMP Snooping detects the Query message from the L3 Switch and logs internally the ports that pass traffic to the L3 Switch L2 Switch eliminates flooding of the local interfaces and passes the Multicast traffic to the L3 Switch for processing. 0 Mbps 5 Mbps 35 Mbps

i MPath N e t w o r k s How does it work? From the Encoder to the L3 Switch Decoder 0 Mbps L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder The L3 Switch detects the Multicast traffic arriving on this interface and logs internally all the Multicast address for distribution. 0 Mbps L3 Switch At this point, the Multicast traffic from all Encoders is combined on this link towards the L3 Switch. 35 Mbps Combined Multicast Traffic 5 Mbps

i MPath N e t w o r k s How does it work? From the L3 Switch to the Decoder Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder 0 Meg L3 Switch Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 1 The operator makes a request to see a video on a specific monitor The Virtual Matrix application forwards a message to the decoder to view a specific video stream on a specific monitor. (request to see video from address ) The Decoder registers this address in its table and forwards the request (“join” the multicast group) to the network The L3 Switch responds and releases the traffic to this specific port on the Ethernet switch. 35 Mbps Combined Multicast Traffic 0 Mbps 5 Mbps

i MPath N e t w o r k s How does it work? From the L3 Switch to the Decoder Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder 35 Mbps 0 Meg L3 Switch Virtual Matrix Control Console Displays video to monitors Controls camera PTZ Control Center # 1 The operator makes a NEW request to see a video on a specific monitor The Virtual Matrix application forwards a message to the decoder to view a specific video stream. ( ) The Decoder registers this address in its table and forwards two messages to the switch The L3 Switch responds by stopping the stream The Decoder sends an IGMP “leave” message. No longer need to receive the Multicast steam ( ) The Decoder sends an IGMP request to join ( ) The L3 Switch responds by forwarding the stream Mbps 5 Mbps

i MPath N e t w o r k s How does it work? Typical Star Topology Decoders L3 Switch Multicast traffic flows from all Encoders to the L3 Switch L3 Switch controls the distribution of all Multicast traffic to Decoders Encoder L2 Switch with IGMP Snooping

i MPath N e t w o r k s Watch for… Limitations of IGMP Snooping Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L3 Switch L2 Switches with IGMP Snooping have limitations. In the event of a communication break between the L2 and L3 switches, the L2 IGMP Snooping switch will behave like a L2 switch A few minutes after loss of signal, the switches may* flood all Multicast signals to the ports of every switch * Behavior may differ depending on switch manufacturer. If this is a Gig E link and you have more then 70 Meg of Video traffic, no other application will run on this network until the link is re-established. Maximum port traffic will be exceeded.

i MPath N e t w o r k s Watch for… Distributed Control Centers L2 Snooping Encoder L3 Switch Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 Multicast traffic flows to the L3 Switch Multicast “join” request sent to the L3 Switch This switch will allow traffic from network A to flow to the Decoder when a “join” request is received. Video Source A Network A

i MPath N e t w o r k s Watch for… Distributed Control Centers L2 Snooping Encoder L3 Switch Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 This switch requires connectivity to the L3 switch to provide local “join” It will not be possible to view any video. Not even local video. Communication break This limitation can be eliminated by installing an L3 Switch at all Control Centers. Video Source A Network A

i MPath N e t w o r k s Watch for… Distributed Control Centers L2 Snooping Encoder L3 Switch Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 L2 Snooping Encoder All Multicast traffic will flow to the L3 Switch Multicast traffic flows to the L3 Switch This switch will only forward traffic from video source B when the Decoder requests to join a video from source B Multicast “join” requests are sent to the L3 Switch Video Source AVideo Source B

i MPath N e t w o r k s Configuration Tips L2 Switch with IGMP Snooping L2 Snooping Encoder L3 Switch Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 L2 Snooping Encoder Two IGMP configuration modes can be set in the switches. Passive This switch generates IGMP Queries. It is considered as the “Master” or the “Active” device In this topology, there can only be one Master unit.

i MPath N e t w o r k s Configuration Tips L2 Switch with IGMP Snooping L2 Snooping Encoder Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 L2 Snooping Encoder Some L2 Switches with IGMP Snooping can be configured as Passive or Active Passive This switch generates IGMP Queries. It is considered as the “Master” or the “Active” device In this topology, there can only be one Master unit. L2 Snooping This topology should only be considered for small networks. Most L2 IGMP Snooping Switches do not have the capacity to handle a large table of IGMP Multicast traffic.

i MPath N e t w o r k s Multi-Vendor Support Avoid…Mixing IGMP Snooping Switches L2 Snooping Encoder Decoder Encoder L2 Snooping Control Center # 2 Decoder Control Center # 1 L2 Snooping Encoder Passive L2 Snooping Although some L2 IGMP Snooping Switch manufacturers may imply that they can integrate into a multi-vendor solution, this is not recommended since IGMP Snooping is not an RFC standard. Implementation differs between manufacturers. (Proven to fail in our labs) Active Manufacturer A Manufacturer B

i MPath N e t w o r k s Multi-Vendor Support Recommendation … Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L3 Switch High end products should be used for L3 Switch to control all your Multicast traffic. Products from Foundry, Extreme, Nortel and Cisco (to name just a few) should be used. These are typically non-hardened products Use L2 with IGMP Snooping “Hardened” products are available Keep it simple. A single manufacturer solution is recommended Several vendors offer a wide range of products for this application. Several (including Magnum 6Ks from GarrettCom) were tested at iMPath with positive results.

i MPath N e t w o r k s Multi-Vendor Support Avoid… Decoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L2 Switch Encoder L3 Switch Do not MIX different vendors IGMP Snooping switches in this topology. It will most-likely not work Manufacturer A Manufacturer B Although some L2 IGMP Snooping Switch vendors may suggest they can integrate into a multi-vendor solution, this is not recommended since IGMP Snooping is not a RFC standard. Implementation differs between manufacturers. (Proven to fail in our labs)

i MPath N e t w o r k s Manufacturer B Manufacturer C Manufacturer A Manufacturer B Manufacturer C Multi-Vendor Support Recommendation… Decoder L3 Switch When multi-vendor solutions are used, it is recommended to use a single manufacturer solution on each link. Use the L3 Switch to separate each group (manufacturer) of L2 IGMP switches. This is the most reliable topology to support multi-vendor solutions.

i MPath N e t w o r k s Credits The information shared in this document was obtained by performing numerous IGMP related tests at iMPath facilities between January and June –Tests were performed using L2, L2 IGMP Snooping, and L3 switches. –Over 30 MPEG-2 iMPath Encoders were used during these tests to validate the proper function and performance of the switches under stress. iMPath would like to thank its business partners for their participations and providing equipment and support during the research phase. –L2 IGMP Snooping switch manufacturers GarrettCom, as well as Etherwan, IFS, Ruggedcom –L3 switch manufacturer Foundry Networks Test Coordinator –iMPath Networks, Daniel Brisson, Sr. System Engineer