Dell PowerConnect B-RX Configuration Manual page 650

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IGMP v3
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 general
queries determine if any interface wants to receive traffic from the router. The following are the
three variants of the Query message:
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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:
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In response to membership reports from the interfaces, the router sends a Group-Specific or a
Group-and-Source Specific query to the multicast interfaces. For example, a router receives a
membership report with a Source-List-Change record to block old sources from an interface. The
router sends Group-and-Source Specific Queries to the source and group (S,G) identified in the
record. If none of the interfaces is interested in the (S,G), it is removed from (S,G) list for that
interface on the router.
Each IGMP V3-enabled router maintains a record of the state of each group and each physical port
within a virtual routing interface. This record contains the group, group-timer, filter mode, and
source records information for the group or interface. Source records contain information on the
source address of the packet and source timer. If the source timer expires when the state of the
group or interface is in Include mode, the record is removed.
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A "General Query" is sent by a multicast router to learn the complete multicast reception state
of the neighboring interfaces. In a General Query, both the Group Address field and the
Number of Sources (N) field are zero.
A "Group-Specific Query" is sent by a multicast router to learn the reception state, with respect
to a *single* multicast address, of the neighboring interfaces. In a Group-Specific Query, the
Group Address field contains the multicast address of interest, and the Number of Sources (N)
field contains zero.
A "Group-and-Source-Specific Query" is sent by a multicast router to learn if any neighboring
interface desires reception of packets sent to a specified multicast address, from any of a
specified list of sources. In a Group-and-Source-Specific Query, the Group Address field
contains the multicast address of interest, and the
source address(es) of interest.
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's 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.
Source-List-Change Record. If the interface wants to add or remove traffic sources from its
membership report, the membership report can have an ALLOW record, which contains a list
of new sources from which the interface wishes to receive traffic. It can also contains a BLOCK
record, which lists current traffic sources from which the interfaces wants to stop receiving
traffic.
Source Address [i] fields contain the
BigIron RX Series Configuration Guide
53-1001810-01