UMN:CLI
User Manual
V8102
546
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MLD Version 2
MLDv2 is based on IGMP3. MLD v2 message consists of two messages as Listener Que-
ry and Listener Report. In addition, Query messages are classified into three types as
General, Multicast-address-specific, Multicast-address-source-specific Query.
0 4 8 16 32
Type
Code
Checksum
Maximum Response Delay
Reserved
Multicast Address (128 bits)
Reserved
S
QRV
QQIC
Number of Sources (n)
Source Address [1] 128bits
…
Source Address [n] 128bits
Fig. 11.2
MLDv2 Query Message Format
MLDv2 Messages
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S (S Flag; Suppress Router-Side Processing):
When a router sends or receives a
query, it must update router’s timer to reflect to correct timeout values for the multicast
address or sources being queried. When set to one, the S Flag indicates to any receiving
multicast routers that they have to suppress the normal timer updates they perform upon
hearing a query.
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QRV
(Querier’s Robustness Variable):
If this is non-zero, it contains the Robustness
Variable value used by the sender of the Query. Routers should update their Robustness
Variable to match the most recently received Query unless the value is zero.
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QQIC
(Querier’s Query Interval Code):
This code is used to specify the Query Interval
value used by the querier.
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Number of Sources (n):
This field specifies how many source addresses are present
in the Query.
This number is zero in a General Query or a Multicast Address Specific
Query, and non-zero in a Multicast Address and Source Specific Query. This number is
limited by the network’s MTU.
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Source Address:
This fields are a vector of n IP unicast address, where n is the value
in the value in the Number of Sources (N) field.
