IGMP Configuration Tasks
455
IGMP group-specific query messages
The query router (querier for short) maintains the IGMP join messages on the
interface on the shared network. After the related features are configured, the
IGMP querier will send IGMP group-specific query messages at the user-defined
interval for the user-defined times when it receives the IGMP leave messages from
the hosts.
Suppose a host in a multicast group decides to leave the multicast group. The
related procedure is as follows:
■
The host sends an IGMP leave packet.
■
When the IGMP querier receives the packet, it will send IGMP group-specific
query messages at the interval configured by the igmp
lastmember-queryinterval
command (the interval is 1 second by default) for
the robust-value times (the robust-value argument is configured by the igmp
robust-count command and it is 2 by default).
■
If other hosts are interested in the group after receiving the IGMP
group-specific query message from the querier, they will send IGMP join
messages in the maximum response time specified in the packet.
■
If the IGMP querier receives IGMP join messages from other hosts within the
robust-value x seconds time, it will maintain the membership of the group.
■
If the IGMP querier does not receive IGMP join messages from other hosts after
the robust-value x seconds time, it considers the group times out and will not
maintain the membership of the group.
The procedure is only fit for the occasion when IGMP queriers runs IGMP version
2.
If the host runs IGMP version 1, it does not send IGMP leave messages when
leaving a group, so the conditions will be the same as described in the procedure
above.
IGMP querier substitution rules
The lifetime of an IGMP querier is limited. If the former querier does not send
query messages in the specified time, another router will replace the IGMP querier.
The maximum query time of IGMP packets
When the host receives a query message, it will set a timer for each of its multicast
groups. The timer value is selected from 0 to the maximum response time at
random. When the value of a timer decreases to 0, the host will send the
membership information of the multicast group.
Through configuring the reasonable maximum response time, you can enable the
host to respond to the query information quickly and enable the Layer 3 switch to
understand the membership information of multicast groups quickly.
Table 364
Configure IGMP query messages
Operation Command Description
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Summary of Contents for Switch 7754
Page 32: ...32 CHAPTER 1 CLI OVERVIEW ...
Page 70: ...70 CHAPTER 5 LOGGING IN USING MODEM ...
Page 76: ...76 CHAPTER 7 LOGGING IN THROUGH NMS ...
Page 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT ...
Page 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION ...
Page 126: ...126 CHAPTER 14 SUPER VLAN ...
Page 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION ...
Page 152: ...152 CHAPTER 17 IPX CONFIGURATION ...
Page 164: ...164 CHAPTER 19 QINQ CONFIGURATION ...
Page 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION ...
Page 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION ...
Page 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION ...
Page 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION ...
Page 224: ...224 CHAPTER 27 DLDP CONFIGURATION ...
Page 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT ...
Page 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION ...
Page 280: ...280 CHAPTER 30 MSTP CONFIGURATION ...
Page 348: ...348 CHAPTER 35 IS IS CONFIGURATION ...
Page 408: ...408 CHAPTER 39 802 1X CONFIGURATION ...
Page 412: ...412 CHAPTER 40 HABP CONFIGURATION ...
Page 422: ...422 CHAPTER 41 MULTICAST OVERVIEW ...
Page 426: ...426 CHAPTER 42 GMRP CONFIGURATION ...
Page 480: ...480 CHAPTER 47 PIM CONFIGURATION ...
Page 506: ...506 CHAPTER 48 MSDP CONFIGURATION ...
Page 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION ...
Page 570: ...570 CHAPTER 53 HA CONFIGURATION ...
Page 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200 ...
Page 622: ...622 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION ...
Page 684: ...684 CHAPTER 61 QOS CONFIGURATION ...
Page 718: ...718 CHAPTER 63 CLUSTER ...
Page 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION ...
Page 752: ...752 CHAPTER 69 RMON CONFIGURATION ...
Page 772: ...772 CHAPTER 70 NTP CONFIGURATION ...
Page 796: ...796 CHAPTER 72 FILE SYSTEM MANAGEMENT ...
Page 802: ...802 CHAPTER 73 BIMS CONFIGURATION ...
Page 814: ...814 CHAPTER 74 FTP AND TFTP CONFIGURATION ...
Page 830: ...830 CHAPTER 75 INFORMATION CENTER ...
Page 836: ...836 CHAPTER 76 DNS CONFIGURATION ...
Page 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING ...
Page 858: ...858 CHAPTER 78 BASIC SYSTEM CONFIGURATION DEBUGGING ...