LAN9312 datasheet(72/458 Pages) SMSC

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High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

Datasheet

Revision 1.2 (04-08-08)

SMSC LAN9312

DATASHEET

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

Table 6.3 Typical Ingress Rate Settings

CIR Setting

Time Per Byte

Bandwidth

0-3

80 nS

100 Mbps

100 nS

80 Mbps

120 nS

67 Mbps

140 nS

57 Mbps

160 nS

50 Mbps

200 nS

40 Mbps

260 nS

31 Mbps

400 nS

20 Mbps

800 nS

10 Mbps

1600 nS

5 Mbps

160

3220 nS

2.5 Mbps

402

8060 nS

1 Mbps

804

16100 nS

500 Kbps

1610

32220 nS

250 Kbps

4028

80580 nS

100 Kbps

8056

161140 nS

50 Kbps

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