Datasheet

KSZ8795CLX
DS00002112B-page 70  2016-2017 Microchip Technology Inc.
The Ipv4/Ipv6 TOS priority control registers implement a fully decoded 64-bit differentiated services code point (DSCP)
register used to determine priority from the 6-bit TOS field in the IP header. The most significant 6 bits of the TOS field
are fully decoded into 64 possibilities, and the singular code that results is mapped to the value in the corresponding bit
in the DSCP register.
4 - 0 Unknown IP
Multicast
Packet
Forward Port
Map
00000 = Filter unknown IP multicast packet
00001 = Forward unknown IP multicast packet to
Port 1
00011 = Forward unknown IP multicast packet to
Port 1, Port 2
00111 = Forward unknown IP multicast packet to
Port 1, Port 2, and Port 3
01111 = Forward unknown IP multicast packet to
Port 1, Port 2, Port 3, and Port 4
11111 = Broadcast unknown IP multicast packet to
all ports
R/W 00000
Register 135 (0x87): Global Control 19
7 - 6 Reserved N/A Don’t Change. RO 00
5 - 4 Ingress Rate
Limit Period
The unit period for calculating Ingress Rate Limit:
00 = 16 ms
01 = 64 ms
1x = 256 ms
R/W 01
3 Queue-
Based
Egress Rate
Limit
Enabled
Enable Queue-Based Egress Rate Limit
0 = Port-Based Egress Rate Limit (default)
1 = Queue-Based Egress Rate Limit
R/W 0
2 Insertion
Source Port
PVID Tag
Selection
Enable
1 = Enable source port PVID tag insertion or non-
insertion option on the egress Port for each source
port PVID-based on the port’s Control 8 Registers.
0 = Disable, all packets from any ingress port will
be inserted PVID-based on Port Control 0 Register
Bit[2].
R/W 0
1 - 0 Reserved N/A Don’t Change. RO 00
TABLE 4-11: ADVANCED CONTROL REGISTERS 144 - 159
Address Name Description Mode Default
Register 144 (0x90): TOS Priority Control Register 0
7 - 6 DSCP[7:6] Ipv4 and Ipv6 Mapping
The value in this field is used as the frame’s priority
when bits [7:2] of the frame’s IP OS/DiffServ/Traffic
Class value is 0x03.
R/W 00
5 - 4 DSCP[5:4] Ipv4 and Ipv6 Mapping
The value in this field is used as the frame’s priority
when bits [7:2] of the frame’s IP OS/DiffServ/Traffic
Class value is 0x02.
R/W 00
3 - 2 DSCP[3:2] Ipv4 and Ipv6 Mapping
The value in this field is used as the frame’s priority
when bits [7:2] of the frame’s IP OS/DiffServ/Traffic
Class value is 0x01.
R/W 00
TABLE 4-10: ADVANCED CONTROL REGISTERS 130 - 135 (CONTINUED)
Address Name Description Mode Default