Brocade Communications Systems IPMC5000PEF manual Overview of IP multicasting, Multicast terms

Overview of IP multicasting

Overview of IP multicasting

Multicast protocols allow a group or channel to be accessed over different networks by multiple stations (clients) for the receipt and transmission of multicast data.

Distribution of stock quotes, video transmissions such as news services and remote classrooms, and video conferencing are all examples of applications that use multicast routing.

Brocade devices support the Protocol-Independent Multicast (PIM) protocol, along with the Internet Group Membership Protocol (IGMP).

PIM is a broadcast and pruning multicast protocol that delivers IP multicast datagrams. This protocol employs reverse path lookup check and pruning to allow source-specific multicast delivery trees to reach all group members. PIM builds a different multicast tree for each source and destination host group.

Multicast terms

The following terms are commonly used in discussing multicast-capable devices. These terms are used throughout this chapter:

Node: A device.

Root Node: The node that initiates the tree building process. It is also the device that sends the multicast packets down the multicast delivery tree.

Upstream: The direction from which a device receives multicast data packets. An upstream device is a node that sends multicast packets.

Downstream: The direction to which a device forwards multicast data packets. A downstream device is a node that receives multicast packets from upstream transmissions.

Group Presence: A multicast group has been learned from one of the directly connected interfaces. Members of the multicast group are present on the device.

Intermediate nodes: Devices that are in the path between source devices and leaf devices.

Leaf nodes: Devices that do not have any downstream devices.

Multicast Tree: A unique tree is built for each source group (S,G) pair. A multicast tree is comprised of a root node and one or more nodes that are leaf or intermediate nodes.

Support for Multicast Multi-VRF

Multicast Multi-VRF support for the Brocade device includes the following:

•PIM (PIM-SM and PIM-DM) The procedure for configuring PIM within a VRF instance is described in the “Enabling PIM on the device and an interface” and the “Configuring global PIM Sparse parameters” sections.

system-max command changes

Several changes have been made to thesystem-maxcommands in support of Multicast Multi-VRF.

The system-maxpim-mcachecommand has been deprecated and replaced by the system max pim- hw-mcachecommand.

FastIron Ethernet Switch IP Multicast Configuration Guide	71
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