Allied Telesis AR400 Initial state, from switch, Switch 2 sends QS, to switch, Switch 1 sends GQ

Query solicitation (rapid recovery from topology changes) > Enabling query solicitation on multiple switches in a looped topology

			Multicast
Initial state:	Switch 1: Querier	Switch 2: STP root	Switch 3
Port on switch 3
is blocking.	Multicast		Multicast
Multicasts flow
from server to
client via switches
1 and 4

1.Link to switch 4

goes down.	Switch 1: Querier	Switch 2: STP root		Switch 3		Switch 4
Switch 3 stops
blocking and	QS from 3		QS from 3
sends Topology
Change (TC) and
Query Solicit (QS).	GQ from 1		GQ from 1		GQ from 1	GQ from 1
Switch 2 forwards
QS to switch 1.			TC from 3		TC from 3
Switch 1 sends
General Query (GQ)

2.Switch 2 receives TC

from switch 3.	Switch 1: Querier	Switch 2: STP root		Switch 3	Switch 4
Switch 2 sends QS.
to switch 1.	QS from 2
Switch 1 sends GQ
	GQ from 1		GQ from 1	GQ from 1	GQ from 1

3.Switch 4 receives TC

from switch 3.	Switch 1: Querier	Switch 2: STP root		Switch 3	Switch 4
Switch 4 sends QS.
towards switch 1.	QS from 4		QS from 4		QS from 4
Switch 1 sends GQ

4.Client replies to each GQ by sending Membership Reports

GQ from 1 GQ from 1 GQ from 1 GQ from 1

Switch 1: Querier Switch 2: STP root Switch 3 Switch 4

Report	Report	Report	Report
Report	Report	Report	Report
Report	Report	Report	Report

Final state:

Multicasts flow from server to client via Switches 1, 2, 3, and 4

Switch 1: Querier Switch 2: STP root Switch 3 Switch 4

Multicast Multicast Multicast Multicast Multicast

igmp-qs.eps

So one topology change caused three Query Solicits, three General Queries, and three Reports.

Page 34 AlliedWare™ OS How To Note: IGMP