LAN9312 datasheet(55/458 Pages) SMSC

55 / 458 page

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

Datasheet

SMSC LAN9312

Revision 1.2 (04-08-08)

DATASHEET

Chapter 6 Switch Fabric

6.1

Functional Overview

At the core of the LAN9312 is the high performance, high efficiency 3 port Ethernet switch fabric. The

switch fabric contains a 3 port VLAN layer 2 switch engine that supports untagged, VLAN tagged, and

priority tagged frames. The switch fabric provides an extensive feature set which includes spanning

tree protocol support, multicast packet filtering and Quality of Service (QoS) packet prioritization by

VLAN tag, destination address, port default value or DIFFSERV/TOS, allowing for a range of

prioritization implementations. 32K of buffer RAM allows for the storage of multiple packets while

forwarding operations are completed, and a 1K entry forwarding table provides room for MAC address

forwarding tables. Each port is allocated a cluster of 4 dynamic QoS queues which allow each queue

size to grow and shrink with traffic, effectively utilizing all available memory. This memory is managed

dynamically via the buffer manager block within the switch fabric. All aspects of the switch fabric are

managed via the switch fabric configuration and status registers (CSR), which are indirectly accessible

via the memory mapped system control and status registers.

The switch fabric consists of four major block types:

Switch Fabric CSRs - These registers provide access to various switch fabric parameters for

configuration and monitoring.

10/100 Ethernet MACs - A total of three MACs are included in the switch fabric which provide basic

10/100 Ethernet functionality for each switch fabric port.

Switch Engine (SWE) - This block is the core of the switch fabric and provides VLAN layer 2

switching for all three switch ports.

Buffer Manager (BM) - This block provides control of the free buffer space, transmit queues, and

scheduling.

Refer to Figure 2.1 Internal LAN9312 Block Diagram on page 21 for details on the interconnection of

the switch fabric blocks within the LAN9312.

6.2

Switch Fabric CSRs

The switch fabric CSRs provide register level access to the various parameters of the switch fabric.

Switch fabric related registers can be classified into two main categories based upon their method of

access: direct and indirect.

The directly accessible switch fabric registers are part of the main system CSRs of the LAN9312 and

are detailed in Section 14.2.6, "Switch Fabric," on page 229. These registers provide switch fabric

manual flow control (Ports 0-2), data/command registers (for access to the indirect switch fabric

registers), and switch MAC address configuration.

The indirectly accessible switch fabric registers reside within the switch fabric and must be accessed

indirectly via the Switch Fabric CSR Interface Data Register (SWITCH_CSR_DATA) and Switch Fabric

CSR Interface Command Register (SWITCH_CSR_CMD), or the set of Switch Fabric CSR Interface

Direct Data Register (SWITCH_CSR_DIRECT_DATA). The indirectly accessible switch fabric CSRs

provide full access to the many configurable parameters of the switch engine, buffer manager, and

each switch port. The switch fabric CSRs are detailed in Section 14.5, "Switch Fabric Control and

Status Registers," on page 308.

For detailed descriptions of all switch fabric related registers, refer to Chapter 14, "Register

Descriptions," on page 166.

LAN9312 Scheda tecnica(PDF) 55 Page - SMSC Corporation

LAN9312 Scheda tecnica(HTML) 55 Page - SMSC Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Scheda tecnica Scarica

Link URL