5. Multicast > Overview
106
Tsi574 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
Once the egress port acknowledges the broadcast buffer’s request, the broadcast buffer transmits
datums to the egress port at sustained rates of up to 10 Gbits/s
1
. The egress port receives the broadcast
buffers data, and can start to transmit that data as soon as the first datum is received.
If a packet is STOMPed when it is received at the broadcast buffer, it is not dropped. The STOMPed
packet is transmitted to the egress port. The broadcast buffer always sets the time-to-live counter value
for a packet copy to the maximum value of seven. For more information, refer to
of Multicast Packets” on page 116
.
The following figure shows a step-by-step multicast operation through the Tsi574 with numbered
descriptions of the events below the diagram.
Figure 22: Multicast Packet Flow in the Tsi574
1. When the ISF clock speed is set to 156.25 MHz.
Ti
p
In RapidIO technology, a datum means a word of data sent in a single clock cycle. When the
Tsi574 is in 4x mode, a datum is 32 bits and in 1x mode, a datum is 8 bits.
Port
0
Port
1
Port
2
Port
7
Internal Switch
Fabric
Port
0
Port
1
Port
2
Multicast
Engine
Work
Queue
Group
Tables
Broadcast
Buffers
Port
7
1
3
4
4
5
7a
9a
Egress
Arbitration
Ingress Port
Egress Port
Vector
Computation
7b
7c
8a
8b
8c
9b
9c
Multicast
Arbitration
2
6
