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
Time Per Byte
Bandwidth
0-3
4
80 nS
100 nS
100 Mbps
80 Mbps
67 Mbps
57 Mbps
50 Mbps
40 Mbps
31 Mbps
20 Mbps
10 Mbps
5 Mbps
5
120 nS
6
140 nS
7
160 nS
9
200 nS
12
260 nS
19
400 nS
39
800 nS
79
1600 nS
3220 nS
8060 nS
16100 nS
32220 nS
80580 nS
161140 nS
160
402
804
1610
4028
8056
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)
SMSC LAN9312
DATA7S2HEET
SMSC [ SMSC CORPORATION ]
