M A G N U M 6 K S W I T C H E S , M N S - 6 K U S E R G U I D E
F
IGURE
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- Using IGMP-L2 on Magnum 6K family of switches, a Layer 2 network can minimize multicast
traffic as shown above. Each switch has the IGMPL2 turned on. Each switch can exchange the IGMP query
message and respond properly. R4 wants to view surveillance traffic from T1. As shown by (1), a join request is
sent by R4. Once the join report information is exchanged, only R4 receives the video surveillance traffic, as shown
by (2). No other device on the network gets the video surveillance traffic unless they issue a join request as well.
R1
R2
R3
R4
R5
R6
T1
T1
T2
T2
L2 Mode
L2 Mode
L2 Mode
L2 Mode
Since the query and the join information is exchanged between the neighboring switches, the
topology does not matter. The design issue to consider is the timing difference between a
topology recovery and IGMP refresh (recovery). GarrettCom Magnum 6K family of switches,
connected in a S-Ring or RS-Ring topology recovers very rapidly (sub-second recovery). The
IGMP requests for updates are sent out every few seconds (depending on the network and the
devices on the network). The recovery of the network from a fault situation is much faster than
the age out and join request from IGMP. Thus when the Magnum 6K switch network self heals,
it is possible that the video may freeze till the (IGMP) device reissues a join request again.
A few additional facts about IGMP L2
•
GarrettCom Magnum 6K family of switches configured for IGMP-L2 can perform the
Join aggregation required by IGMP
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