Chapter 24 Multicast
GS2210 Series User’s Guide
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one quer y fr om a r out er ( X ) or MLD Done or Repor t m essage fr om any upst r eam por t , it will be
br oadcast t o all connect ed upst r eam por t s.
MLD Messages
A m ult icast r out er or sw it ch per iodically sends general quer ies t o MLD host s t o updat e t he m ult icast
for warding t able. When an MLD host want s t o j oin a m ult icast group, it sends an MLD Repor t
m essage for t hat addr ess.
An MLD Done m essage is sim ilar t o an I GMP Leave m essage. When an MLD host want s t o leave a
m ult icast gr oup, it can send a Done m essage t o t he r out er or sw it ch. I f t he leave m ode is not set t o
I m m e dia t e , t he r out er or sw it ch sends a gr oup- specific quer y t o t he por t on w hich t he Done
m essage is r eceived t o det er m ine if ot her devices connect ed t o t his por t should r em ain in t he
gr oup.
MVR Overview
Mult icast VLAN Regist rat ion ( MVR) is designed for applicat ions ( such as Media- on- Dem and ( MoD) )
t hat use m ult icast t raffic across an Et her net r ing- based ser vice pr ovider net w or k.
MVR allow s one single m ult icast VLAN t o be shar ed am ong differ ent subscr iber VLANs on t he
net w or k. While isolat ed in differ ent subscr iber VLANs, connect ed devices can subscr ibe t o and
unsubscr ibe fr om t he m ult icast st r eam in t he m ult icast VLAN. This im pr oves bandw idt h ut ilizat ion
w it h r educed m ult icast t raffic in t he subscr iber VLANs and sim plifies m ult icast gr oup m anagem ent .
MVR only r esponds t o I GMP j oin and leave cont r ol m essages fr om m ult icast gr oups t hat ar e
configured under MVR. Join and leave r epor t s from ot her m ult icast gr oups ar e m anaged by I GMP
snooping.
The follow ing figur e show s a net w or k exam ple. The subscr iber VLAN ( 1 , 2 and 3 ) infor m at ion is
hidden from t he st ream ing m edia server, S. I n addit ion, t he m ult icast VLAN infor m at ion is only
visible t o t he Sw it ch and S.
1
2
3
4
5
6
7
8
9
X
Done
Query
Report
