Allied Telesis AR400 - Manual (Page 34)

Page 34 | AlliedWare™ OS How To Note: IGMP
Query solicitation (rapid recovery from topology changes) > Enabling query solicitation on multiple switches in a looped topology
So one topology change caused three Query Solicits, three General Queries, and three
Reports.
Switch 1: Querier Switch 3 Switch 2: STP root
Initial state:
Port on switch 3
is blocking.
Multicasts flow
from server to
client via switches
1 and 4
Multicast
Multicast
Multicast
Multicast Multicast
Switch 1: Querier Switch 3 Switch 2: STP root Switch 4
Final state:
Multicasts flow
from server to
client via Switches
1, 2, 3, and 4
Multicast Multicast Multicast
QS from 3
1. Link to switch 4
goes down.
Switch 3 stops
blocking and
sends Topology
Change (TC) and
Query Solicit (QS).
Switch 2 forwards
QS to switch 1.
Switch 1 sends
General Query (GQ)
Switch 3 Switch 2: STP root Switch 4
TC from 3
QS from 3
GQ from 1 GQ from 1 GQ from 1 GQ from 1
TC from 3
Switch 1: Querier
2. Switch 2 receives TC
from switch 3.
Switch 2 sends QS.
to switch 1.
Switch 1 sends GQ
Switch 3 Switch 2: STP root Switch 4
QS from 2
GQ from 1 GQ from 1 GQ from 1 GQ from 1
Switch 1: Querier
QS from 4
3. Switch 4 receives TC
from switch 3.
Switch 4 sends QS.
towards switch 1.
Switch 1 sends GQ
Switch 3 Switch 2: STP root Switch 4
QS from 4
GQ from 1 GQ from 1 GQ from 1 GQ from 1
Switch 1: Querier
QS from 4
4. Client replies to each
GQ by sending
Membership Reports
Switch 3 Switch 2: STP root Switch 4 Switch 1: Querier
Report Report Report Report
Report Report Report Report
Report Report Report Report
igmp-qs.eps