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Page 30 | AlliedWare™ OS How To Note: IGMP
Query solicitation (rapid recovery from topology changes) > Why convergence takes so long without query solicitation
When link
comes up
again
When we reconnect port 1 on the Snooper, the All Groups entry does not reappear.
Eventually, the Querier sends an IGMP Query, which the Snooper receives on port 1. This
restores the All Groups port on the Snooper. By default the Querier sends General Queries
every 125 seconds, so the IGMP convergence delay will be up to 125 seconds with the
default settings. For more information about this timeout, see "Configurable IGMP timers
and counters" on page 69—but do not change the timeout without very carefully considering
the effect on your network.
When the Snooper receives the General Query, it forwards it out all its ports. The client
responds with a Report. The Snooper forwards the Report out its All Groups port towards
the Querier. The Querier responds by sending the multicast stream to the Snooper, which
forwards the multicast stream out port 9 to the client.
Manager Switch 2> show igmpsnooping
IGMP Snooping
------------------------------------------------------------------------
Status ........................... Enabled
Disabled All-groups ports ........ None
Vlan Name (vlan id) ..... default (1)
Fast Leave .............. Off
Query Solicitation ...... Off
Static Router Ports ..... None
Group List ..............
Group. 224.12.13.14 Entry timeout 140 secs
Ports 9
------------------------------------------------------------------------
Manager Switch 2> show igmpsnooping
IGMP Snooping
------------------------------------------------------------------------
Status ........................... Enabled
Disabled All-groups ports ........ None
Vlan Name (vlan id) ..... default (1)
Fast Leave .............. Off
Query Solicitation ...... Off
Static Router Ports ..... None
Group List ..............
Group. 224.12.13.14 Entry timeout 107 secs
Ports 9
All Groups Entry timeout 236 secs
Ports 1
------------------------------------------------------------------------