Cisco IE-5000 User Manual

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Configuring IP Multicast Routing
Information About Cisco’s Implementation of IP Multicast Routing
Figure 87 RPF Check
PIM uses both source trees and RP-rooted shared trees to forward datagrams (described in the PIM DM, page 678 and
the PIM SM, page 678). The RPF check is performed differently for each:
 If a PIM router or multilayer switch has a source-tree state (that is, an (S,G) entry is present in the multicast routing
table), it performs the RPF check against the IP address of the source of the multicast packet.
 If a PIM router or multilayer switch has a shared-tree state (and no explicit source-tree state), it performs the RPF
check on the RP address (which is known when members join the group).
Sparse-mode PIM uses the RPF lookup function to decide where it needs to send joins and prunes:
 (S,G) joins (which are source-tree states) are sent toward the source.
 (*,G) joins (which are shared-tree states) are sent toward the RP.
Dense-mode PIM uses only source trees and uses RPF as previously described.
Information About Source-Specific Multicast
The Source-Specific Multicast (SSM) feature is an extension of IP multicast in which datagram traffic is forwarded to
receivers from only those multicast sources that the receivers have explicitly joined. For multicast groups configured for
SSM, only SSM distribution trees (no shared trees) are created.
SSM Components Overview
SSM is a datagram delivery model that best supports one-to-many applications, also known as broadcast applications.
SSM is a core networking technology for the Cisco implementation of IP multicast solutions targeted for audio and video
broadcast application environments. The switch supports these components that support the implementation of SSM:
 Protocol independent multicast source-specific mode (PIM-SSM)
PIM-SSM is the routing protocol that supports the implementation of SSM and is derived from PIM sparse mode
(PIM-SM).
 Internet Group Management Protocol version 3 (IGMPv3)
Network Port
151.10.0.0/16 Gigabit Ethernet 0/1
198.14.32.0/32 Fast Ethernet 0/1
204.1.16.0/24 Fast Ethernet 0/2
Multicast
packet from
source 151.10.3.21
is forwarded.
Multicast
packet from
source 151.10.3.21
packet is discarded.
Gigabit Ethernet 0/1
Fast Ethernet 0/1
Fast Ethernet 0/2
Gigabit Ethernet 0/2
141002
Layer 3 switch

Cisco IE-5000 Specifications

General

Brand	Cisco
Model	IE-5000
Category	Switch
Language	English