Brocade TurboIron 24X Series Configuration Guide - Manual (Page 888)

854 Brocade TurboIron 24X Series Configuration Guide
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IGMP V3
NOTE
This display shows the PIM interface configuration information, but does not show the link states for
the interfaces.
The information in brackets indicates the following:
• The multicast interface type (always PIM)
• The Time-to-Live (TTL) for the interface.
• The metric for the interface
• Whether the interface is connected to a leaf node (“leaf” indicates a leaf node and blank
indicates another PIM router)
For example, the information for the first interface listed in the display is “PIM/0 /1”. This
information indicates that the interface is a PIM interface, has a TTL of 0, and a metric of 1. The
interface is not a leaf node interface and thus is an interface to another PIM router.
The information for the second interface in the display is “PIM/0 /1/leaf”. This information
indicates that the interface is a PIM interface, has a TTL of 0 and a metric of 1, and is connected to
a leaf node.
IGMP V3
The Internet Group Management Protocol (IGMP) allows an IPV4 interface to communicate IP
Multicast group membership information to its neighboring routers. The routers in turn limit the
multicast of IP packets with multicast destination addresses to only those interfaces on the router
that are identified as IP Multicast group members. This release introduces the support of IGMP
version 3 (IGMP V3) on Layer 3 Switches.
In IGMP V2, when a router sent a query to the interfaces, the clients on the interfaces respond with
a membership report of multicast groups to the router. The router can then send traffic to these
groups, regardless of the traffic source. When an interface no longer needs to receive traffic from a
group, it sends a leave message to the router which in turn sends a group-specific query to that
interface to see if any other clients on the same interface is still active.
In contrast, IGMP V3 provides selective filtering of traffic based on traffic source. A router running
IGMP V3 sends queries to every multicast enabled interface at the specified interval. These queries
determine if any interface wants to receive traffic from the router. The queries include the IP
address of the traffic source (S) or the ID of the multicast group (G, or both).
The interfaces respond to these queries by sending a membership report that contains one or
more of the following records that are associated with a specific group:
• Current-State Record that indicates from which sources the interface wants to receive and not
receive traffic. The record contains source address of interfaces and whether or not traffic will
be received or included (IS_IN) or not received or excluded (IS_EX) from that source.
• Filter-mode-change record. If the interface changes its current state from IS_IN to IS_EX, a
TO_EX record is included in the membership report. Likewise, if an interface current state
changes from IS_EX to IS_IN, a TO_IN record appears in the membership report.
IGMP V2 Leave report is equivalent to a TO_IN(empty) record in IGMP V3. This record means
that no traffic from this group will be received regardless of the source.
An IGMP V2 group report is equivalent to an IS_EX(empty) record in IGMP V3. This record
means that all traffic from this group will be received regardless of source.