LAN9312 Datasheet, PDF (72/458 Pages) SMSC Corporation – High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
Table 6.3 Typical Ingress Rate Settings
CIR Setting
0-3
4
5
6
7
9
12
19
39
79
160
402
804
1610
4028
8056
Time Per Byte
80 nS
100 nS
120 nS
140 nS
160 nS
200 nS
260 nS
400 nS
800 nS
1600 nS
3220 nS
8060 nS
16100 nS
32220 nS
80580 nS
161140 nS
Bandwidth
100 Mbps
80 Mbps
67 Mbps
57 Mbps
50 Mbps
40 Mbps
31 Mbps
20 Mbps
10 Mbps
5 Mbps
2.5 Mbps
1 Mbps
500 Kbps
250 Kbps
100 Kbps
50 Kbps
After each packet is received, the bucket is decremented. If the Committed Burst bucket has sufficient
tokens, it is debited and the packet is colored Green. If the Committed Burst bucket lacks sufficient
tokens for the packet, the Excess Burst bucket is checked. If the Excess Burst bucket has sufficient
tokens, it is debited, the packet is colored Yellow and is subjected to random discard. If the Excess
Burst bucket lacks sufficient tokens for the packet, the packet is colored Red and is discarded.
Note:
All of the token buckets are initialized to the default value of 1536. If lower values are
programmed into the CBS and EBS parameters, the token buckets will need to be normally
depleted below these values before the values have any affect on limiting the maximum value
of the token buckets.
Refer to Section 14.5.3.25, on page 394 through Section 14.5.3.29, on page 399 for detailed register
descriptions.
6.4.6.1
Ingress Flow Calculation
Based on the flow monitoring mode, an ingress flow definition can include the ingress priority. This is
calculated similarly to the transmit queue with the exception that the Priority Regeneration and the
Traffic Class table are not used. As shown in Figure 6.7, the priority can be based on:
„ The precedence bits in the IPv4 TOS octet
„ The DIFFSERV mapping table indexed by the IPv4 TOS octet or the IPv6 Traffic Class octet
„ The VLAN tag priority field (but not through the per port Priority Regeneration table)
„ The port default
Revision 1.2 (04-08-08)
72
DATASHEET
SMSC LAN9312