Zte ZXR10 5900E Series - Figure 23 IGMP SNOOPING APPLICATION; Multicast Group Join; Multicast Group Leave

ZXR105900ESeriesUserManual(EthernetSwitchingVolume)
FIGURE23IGMPSNOOPINGAPPLICATION
MulticastGroupJoin
ThehostjoinscorrespondingmulticastgroupbysendinganIGMP
joiningmessage.WhentheswitchreceivestheIGMPhostreport
fromahostforaparticularmulticastgroup,theswitchaddsthe
portnumberofthehosttotheassociatedmulticasttableentry.
WhenotherhostsinthesameVLANareinterestedinthemulticast
trafcandsendamembershipreport,theswitchaddsthemtothe
existedforwardingentries.
Switchcreatesonlyoneforwardingentryforeachmulticastgroup
inthesameVLAN,forwardsthemulticasttrafcofthemulticast
groupinallportsreceivingthemembershipreport.
MulticastGroupLeave
HoststhatjoinedmulticastgroupmustrespondtoIGMPquery
messagetransmittedbyrouterperiodically.Aslongasonehost
respondstoIGMPqueryinaVLAN,theroutermustcontinuefor-
wardingtrafcofthemulticastgroupthatthehostjoinedtothe
VLAN.
Whenahostwantstoleaveamulticastgroup,itcouldignore
theIGMPquerymessagetransmittedbyrouterperiodically(called
“leavequietly”),orsendIGMPv2leavemessageofspecicgroup.
WhenIGMPSnoopinghearsIGMPv2leavemessageofspecic
group,theswitchsendsspecicgroupquerymessagetotheport
receivingthemessagetoquerywhetherotherhostsbelongingto
themulticastgroupareavailableinthisport.IfIGMPSnooping
cannotreceiveanyresponsemessageafterseveralqueries,itin-
dicatesthattherearenohostsbelongingtothemulticastgroup
88CondentialandProprietaryInformationofZTECORPORATION