Avaya 8800 Planning And Engineering, Network Design page 224

Multicast network design
Figure 107: Multicast and SMLT design that avoids duplicate traffic
Assume that the source network is 10.10.10.0/24, switches A and B know the DVMRP metric for the
IST interface, the interfaces towards NETWORK are all configured as 10, and the total cost to the
source is the same.
• A has a DVMRP route 10.10.10.0 with a metric of 10 and an upstream neighbor through the
interface connecting to NETWORK.
• B has a DVMRP route 10.10.10.0 with a metric of 10 and an upstream neighbor through the
interface connecting to NETWORK.
A and B learn the DVMRP route for the sender (S) network with the same metric:
• Assume that A is the querier for the interface connected to the IGMP Snoop-enabled switch.
• When receiver R sends an IGMP report, A learns the receiver on the SMLT port and forwards
the IST-IGMP message to B.
• After B receives the message from A, B learns the receiver on its SMLT port connected to the
IGMP switch. So, both A and B have local receivers on their SMLT port.
• S sends data that is received by both A and B through the interface connected to NETWORK.
Because both A and B have a local receiver on the SMLT port, the IGMP switch receives data
from both the routers, causing R to receive duplicate traffic.
June 2016 Planning and Engineering — Network Design
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