Specifications

Disabling or Reenabling Proxy Reporting
14-2 Configuring and Managing IGMP Snooping
Disabling or Reenabling Proxy Reporting
Proxyreportingreducesmulticastoverheadbysendingonlyonereportforeachactivegroupto
themulticastrouters,insteadofsendingaseparatereportfromeachmulticastreceiver.For
example,iftheRoamAboutSwitchreceivesreportsfromthree receiversformulticastgroup
237.255.255.255,theswitchsendsonlyonereportforthe
grouptotherouters.Onereportis
sufficienttocausetherouterstocontinuesendingdataforthegroup.Proxyreportingisenabled
bydefault.
Todisableorreenableproxyreporting,usethefollowingcommand:
set igmp proxy-report {enable | disable} [vlan vlan-id]
Enabling the Pseudo-Querier
TheIGMPpseudo‐querierenablesIGMPsnoopingtooperateinaVLANthatdoesnothavea
multicastroutertosendIGMPgeneralqueriestoclients.
Toenablethepseudo‐querier,usethefollowingcommand:
set igmp querier {enable | disable} [vlan vlan-id]
Changing IGMP Timers
YoucanchangethefollowingIGMPti mers:
•Queryinterval—Numberofsecondsthatelapsebetweengeneralqueriessentbytheswitchto
advertisemulticastgroups.
•Other‐querier‐presentinterval—NumberofsecondsthattheRoamAboutSwitchwaitsfora
generalquerytoarrivefromanotherquerierbeforeelectingitselfthequerier.
•Queryresponseinterval—Number
oftenthsofasecondthattheRoamAboutSwitchwaitsfor
areceivertorespond toagroup‐specificquerymessagebeforeremovingthereceiverfromthe
receiverlistforthegroup.
• Lastmemberqueryinterval—Numberoftenthsofasecondthattheswitchwaitsfora
responsetoagroup
‐specificqueryafterreceivingaleavemessageforthatgroup,before
removingthereceiverthatsenttheleavemessagefromthelistofreceiversforthegroup.If
therearenomorereceiversforthegroup,theswitchalsosendsaleavemessageforthegroup
tomulticastrouters.
•Robustnessvalue—Number
usedasamultipliertoadjusttheIGMPtimerstotheamountof
trafficlossthatoccursonthenetwork.Settherobustnessvaluehighertoadjustformore
trafficloss.
Note: Enterasys Networks recommends that you use the pseudo-querier only when the VLAN
contains local multicast traffic sources and no multicast router is servicing the subnet.
Note: The query interval, other-querier-present interval, and query response interval are applicable
only when the RoamAbout Switch is querier for the subnet. For the switch to become the querier, the
pseudo-querier feature must be enabled on the switch and the switch must have the lowest IP
address among all the devices eligible to become a querier. To enable the pseudo-querier feature,
see “Enabling the Pseudo-Querier” on page 14-2.