5. Multicast > Arbitration for Multicast Engine Ingress Port
115
Tsi574 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
Figure 25: IDT-specific Multicast Mask Configuration
5.3
Arbitration for Multicast Engine Ingress Port
The arbitration scheme used to handle multiple ingress accesses to the Multicast engine ingress port is
simple Round Robin (RR) arbitration followed by the Strict Priority (SP) arbitration (see
Each ingress port goes through RR arbitration based on their priority group. The outputs of the RR
arbitration are handled with SP arbitration where higher priority packets are sent before lower priority
ones.
The RR arbiter looks through the ports sequentially starting from Port 0, one after the other, to accept
packets when available. No one port can monopolize the RR arbiter. When a port skips an opportunity
to transmit because it carries no packet at the moment, the RR arbiter does not compensate for the lost
chance and moves to the next port, in sequence, for an available packet.
The packets from the RR arbiters are selected by the SP arbiter based solely on their priority.
Port Participating in Vector
F
E
D
C
B
A
9
8
7
6
5
4
3
2
1
0
0
1
2
4
3
5
6
7
DEST_ID
Large Small
Multicast
Mask
Number
12
34
xx
44
0
1
Switch Port Number
0 = No
1 = Yes
1
0
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
{
Multicast
Write ID
bits [16: 31]
in the
RIO_MC_ID[0..7]
registers
{
Multicast Vector Table
bits [0:15] in the RIO_MC_MSK[0..7]
registers
FE
ED
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
{
Multicast
Mask
Number
RIO_MC_MSK[0..7]
0x10320
0x10324
0x10328
0x1032C
0x10330
0x10334
0x10338
0x1033C
0x10300
0x10304
0x10308
0x1030C
0x10310
0x10314
0x10318
0x1031C
