IP Multicast over Fabric Connect provides simplicity in provisioning and deploying IP multicast bridging and routing. Also, due to the fact that only one control plane protocol (IS-IS) exists, convergence times in the event of a network failure, are typically sub second.
IP Multicast over Fabric Connect introduces extensions to the SPBM IS-IS control plane to exchange IP multicast stream advertisement and membership information. IP Multicast over Fabric Connect uses these extensions, along with the Internet Group Management Protocol (IGMP) Snooping and Querier functions at the edge of the SPBM cloud, to create sub-trees of the VSN SPB for each multicast group to transport IP multicast data.
With IP Multicast over Fabric Connect, the switch supports the following:
Layer 2 Virtual Services Network with IGMP support on the access networks for optimized forwarding of IP multicast traffic in a bridged network (Layer 2 VSN with IP Multicast over Fabric Connect). Example application: Multicast in data centers.
IP multicast routing support for IP Shortcuts using SPBM in the core and IGMP on the access (IP Shortcuts with IP Multicast over Fabric Connect). Example applications: Video surveillance, TV/Video/Ticker/Image distribution, VX-LAN.
Layer 3 Virtual Services Network with VRF based routing support for IP Multicast over Fabric Connect in the core and IGMP on the access (Layer 3 VSN with IP Multicast over Fabric Connect). Example applications: Video surveillance, TV/Video/Ticker/Image Distribution, VXLAN, Multi-tenant IP multicast.
Important
Sources must be IGMP enabled to support discovery functions specific to the multicast applications in use.
IP Multicast over Fabric Connect cannot connect to an IP Multicast router outside the SPB network.
You can only deploy IP Multicast over Fabric Connect in environments where there are no multicast routers between the edge of the SPB network and the IP Multicast hosts that connect to the network.
An existing network which is Protocol Independent Multicast (PIM) based cannot participate in the SPB network either by connecting to SPB originated streams or by injecting PIM network streams into the SPB network.
In certain environments it is not possible to deploy an SPB network all the way to the point where the SPB network directly connects to an IGMP edge.
You encounter these restrictions during the following typical deployment scenarios:
Scenario 1: You deployed IP Multicast using PIM and want to expand the network by deploying SPB for the new portion of the network. You want multicast applications to work across the old and new portion of the network.
Scenario 2: Multicast traffic is exchanged between independent network operators at the boundary between their networks. PIM is the multicast routing protocol. A network operator wants to upgrade or replace the existing network to an SPB network. The inter-domain multicast traffic exchanges with other networks should not be disrupted.
The following figure shows the traditional Multicast over Fabric Connect environment with no PIM routers.
In the previous figure, sources and receivers on the edges of the SPB network are IGMP hosts and sources of multicast data. Hence, the traditional Multicast over Fabric Connect host-to-host deployment works.
The following figure shows the traditional Multicast over Fabric Connect environment with PIM routers.
In the previous figure, sources and receivers on the edges of the SPB network, which are IGMP or source hosts can communicate over the SPB network. Sources and receivers connected to PIM routers cannot participate in the SPB network.