168
The IGMP Type codes are shown below:
Type Meaning
0x11
Membership Query (if Group Address is 0.0.0.0)
0x11
Specific Group Membership Query (if Group Address is
Present)
0x16
Membership Report (version 2)
0x17
Leave a Group (version 2)
0x12
Membership Report (version 1)
IGMP packets enable multicast routers to keep track of the membership of multicast groups, on their respective sub
networks. The following outlines what is communicated between a multicast router and a multicast group member
using IGMP.
A host sends an IGMP
“report”
to join a group
A host will never send a report when it wants to leave a group (for version 1).
A host will send a
“leave”
report when it wants to leave a group (for version 2).
Multicast routers send IGMP queries (to the all-hosts group address: 224.0.0.1) periodically to see whether any group
members exist on their sub networks. If there is no response from a particular group, the router assumes that there are
no group members on the network.
The Time-to-Live (TTL) field of query messages is set to 1 so that the queries will not be forwarded to other sub
networks.
IGMP version 2 introduces some enhancements such as a method to elect a multicast queried for each LAN, an
explicit leave message, and query messages that are specific to a given group.
The states a computer will go through to join or to leave a multicast group are shown below:
Содержание NS3500-28T-4S
Страница 1: ...NS3500 28T 4S User Manual P N 1072835 REV 00 01 ISS 14JUL14 ...
Страница 41: ...41 3 Press the Apply button to save running configuration to startup configuration ...
Страница 145: ...145 Figure 4 6 2 Before Applying the STA Rules In this example only the default STP values are used ...
Страница 166: ...166 Figure 4 7 4 Multicast Flooding ...
Страница 255: ...255 The page includes the following fields Object Description DHCP Snooping Display the current DHCP snooping status ...
Страница 260: ...260 Buttons Click to clear the statistics Click to refresh the statistics ...
Страница 282: ...282 Figure 4 9 66 Global DoS Setting Page Screenshot ...
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