Configuration Guide User guide

FastIron Configuration Guide 1517
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Global IP multicast parameters
Supported Layer 3 multicast routing protocols
Brocade Layer 3 switches support the multicast routing protocol DVMRP and PIM along with the
Internet Group Membership Protocol (IGMP).
PIM and DVMRP are broadcast and pruning multicast protocol that deliver IP multicast datagrams.
The protocol employs reverse path lookup check and pruning to allow source-specific multicast
delivery trees to reach all group members. DVMRP and PIM build a different multicast tree for each
source and destination host groups.
NOTE
DVMRP and PIM can concurrently operate on different ports of a Brocade Layer 3 switch.
Suppression of unregistered multicast packets
Be default, unregistered multicast packets are always forwarded in hardware but not copied to the
CPU. However on FSX platforms, if Layer 2 multicast (IGMP or MLD) or Layer 3 multicast (router
pim) is enabled, then unregistered multicast packets are forwarded in hardware and also copied to
the CPU.
Multicast terms
The following are commonly used terms in discussing multicast-capable routers. These terms are
used throughout this chapter:
• Node: Refers to a router or Layer 3 switch.
• Root Node: The node that initiates the tree building process. It is also the router that sends the
multicast packets down the multicast delivery tree.
• Upstream: Represents the direction from which a router receives multicast data packets. An
upstream router is a node that sends multicast packets.
• Downstream: Represents the direction to which a router forwards multicast data packets. A
downstream router is a node that receives multicast packets from upstream transmissions.
• Group Presence: Means that a multicast group has been learned from one of the directly
connected interfaces. Members of the multicast group are present on the router.
• Intermediate nodes: Routers that are in the path between source routers and leaf routers.
• Leaf nodes: Routers that do not have any downstream routers.
• 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.
Global IP multicast parameters
The following configurable parameters apply to PIM-DM, PIM-SM and DVMRP
• Maximum number of PIM groups – You can change the maximum number of groups of each
type for which the software will allocate memory. By default, FastIron X Series Layer 3 switches
support up to 1024 PIM groups. Brocade FCX Series Layer 3 switches support up to 4000 PIM
groups.