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Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
Revision 1.4 (08-19-08) 20 SMSC LAN9311/LAN9311i
DATASHEET
Chapter 2 Introduction
2.1 General Description
The LAN9311/LAN9311i is a full featured, 2 port 10/100 managed Ethernet switch designed for
embedded applications where performance, flexibility, ease of integration and system cost control are
required. The LAN9311/LAN9311i combines all the functions of a 10/100 switch system, including the
switch fabric, packet buffers, buffer manager, media access controllers (MACs), PHY transceivers, and
host bus interface. The LAN9311/LAN9311i complies with the IEEE 802.3 (full/half-duplex 10BASE-T
and 100BASE-TX) Ethernet protocol specification and 802.1D/802.1Q network management protocol
specifications, enabling compatibility with industry standard Ethernet and Fast Ethernet applications.
At the core of the LAN9311/LAN9311i 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 ample 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, which are indirectly
accessible via the memory mapped system control and status registers.
The LAN9311/LAN9311i provides 2 switched ports. Each port is fully compliant with the IEEE 802.3
standard and all internal MACs and PHYs support full/half duplex 10BASE-T and 100BASE-TX
operation. The LAN9311/LAN9311i provides 2 on-chip PHYs, 1 Virtual PHY and 3 MACs. The Virtual
PHY and the Host MAC are used to connect the LAN9311/LAN9311i switch fabric to the host bus
interface. All ports support automatic or manual full duplex flow control or half duplex backpressure
(forced collision) flow control. Automatic 32-bit CRC generation/checking and automatic payload
padding are supported to further reduce CPU overhead. 2K jumbo packet (2048 byte) support allows
for oversized packet transfers, effectively increasing throughput while deceasing CPU load. All MAC
and PHY related settings are fully configurable via their respective registers within the
LAN9311/LAN9311i.
The integrated Host Bus Interface (HBI) easily interfaces to most 16-bit embedded CPU’s via a simple
SRAM like interface, enabling switch fabric access via the internal Host MAC and allowing full control
over the LAN9311/LAN9311i via memory mapped system control and status registers. The HBI
supports 16-bit operation with big, little, and mixed endian operations. Four separate FIFO mechanisms
(TX/RX Data FIFO’s, TX/RX Status FIFO’s) interface the HBI to the Host MAC and facilitate the
transferring of packet data and status information between the host CPU and the switch fabric. The
LAN9311/LAN9311i also provides power management features which allow for wake on LAN, wake on
link status change (energy detect), and magic packet wakeup detection. A configurable host interrupt
pin allows the device to inform the host CPU of any internal interrupts.
The LAN9311/LAN9311i contains an I
2
C/Microwire master EEPROM controller for connection to an
optional EEPROM. This allows for the storage and retrieval of static data. The internal EEPROM
Loader can be optionally configured to automatically load stored configuration settings from the
EEPROM into the LAN9311/LAN9311i at reset.
In addition to the primary functionality described above, the LAN9311/LAN9311i provides additional
features designed for extended functionality. These include a configurable 16-bit General Purpose
Timer (GPT), a 32-bit 25MHz free running counter, a 12-bit configurable GPIO/LED interface, and IEEE
1588 time stamping on all ports and select GPIOs. The IEEE time stamp unit provides a 64-bit tunable
clock for accurate PTP timing and a timer comparator to allow time based interrupt generation.
The LAN9311/LAN9311i’s performance, features and small size make it an ideal solution for many
applications in the consumer electronics and industrial automation markets. Targeted applications
include: set top boxes (cable, satellite and IP), digital televisions, digital video recorders, voice over IP
and video phone systems, home gateways, and test and measurement equipment.