L-ET4148-50C-DB LSI, L-ET4148-50C-DB Datasheet - Page 168

• Manufacturer Part Number: L-ET4148-50C-DB
• Manufacturer: LSI

Specifications of L-ET4148-50C-DB

• Lead Free Status / RoHS Status: Supplier Unconfirmed

ET4148-50
Single-Chip 48 x 1 Gbit/s + 2 x 10 Gbits/s Layer 2+ Ethernet Switch
Appendix A: Registers
Packet_Buffer_Mode
Description: Mode bits.
Table 221. Packet_Buffer_Mode Register Parameters
Table 222. Packet_Buffer_Mode Field Parameters
Various basic mode bits related to packet_buffer.
168
Base Address
Register Size
Register Instances
Register Spacing
Record Size
Record Instances
Record Spacing
global_congestion_hysteresis[9:4]
hol_mode
bandwidth_provisioning_en
weighted_round_robin_en
0
Parameter
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
Field Name
1
2
3
4
5
6
Figure 161. Packet_Buffer_Mode Register Diagram
(continued)
7
8
Mode = R/W
Offset = 0.29
Instances = 1
Instances = 1
Instances = 1
Instances = 1
0x000c_bc64
Offset = 0.31
Mode = R/W
Mode = R/W
Mode = R/W
Parameters
Offset = 22
Offset = 30
9
Value
NA
NA
10
4
1
4
1
Agere Systems - Proprietary
11
12
This field establishes the congestion hysteresis. The number of
allocated buffers must fall below
global_congestion_threshold[14:8] minus
global_congestion_hysteresis[9:4] for the state to
change from congested to not congested. This hysteresis value is
shared by all congestion thresholds.
When asserted, packet_buffer utilizes queue and buffer
thresholds to manage and avoid head-of-line blocking scenarios in
the shared resources.
When this bit is asserted, the
Packet_Buffer_Queue_Management_Threshold,
Packet_Buffer_Queue_Limit, and
Packet_Buffer_Queue_Buffer_Limit registers may be
programmed. This bit is valid only in revision C and is reserved in
revisions B and B1.
This bit is asserted to enable the bandwidth provisioning (traffic
shaping) algorithms. When this mode is enabled, a queue must be
nonempty and below its bandwidth limit prior to transmission.
When this mode is disabled, a queue need only be nonempty to
arbitrate for transmission.
When asserted, packet_buffer utilizes a weighted round-robin
arbitration method among the queues that are ready to transmit for
a particular port. Otherwise, strict priority is used. Readiness for
transmission is determined by the traffic-shaping algorithms.
13
14
15
16
17
18
19
20
21
Description
22
23
8
Preliminary Data Sheet
24
7
25
6
26
5
Agere Systems Inc.
27
4
28
3
April 2006
29
2
30
1
31
0