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Single-Chip 4-Port 10/100Mbps Ethernet Switch Controller with Dual MII/RMII Interfaces
General Description

The RTL8304E-CG is a 4-port Fast Ethernet switch controller that integrates memory, four MACs, and two physical layer transceivers for 10Base-T and 100Base-TX operation into a single chip.


The RTL8304E supports two MII/RMII interface for external devices to connect to the 3rd and 4th MACs. The external device could be a routing engine, HomePNA, HomePlug, or another processor depending on the application.


The RTL8304E supports several advanced QoS functions with four-level priority queues to improve multimedia or real-time networking applications, including:

·       Multi-priority assignment

·       Differential queue weight

·       Port-based and queue-based rate limitation

·       16-entry ACL for advanced packet control application


For multicast applications, the RTL8304E supports IGMPv1/v2/v3 and MLDv1/v2 snooping.


To meet security and management requirements, the RTL8304E supports IEEE 802.1x Port-based/MAC-based Access Control, MAC Address Limits, Port Isolation, Port Mirroring, and also supports five 32-bit MIB Counters on each port.


The RTL8304E supports 16 VLAN groups. These can be configured as port-based VLANs and/or 802.1Q tag-based VLANs. The RTL8304E also supports VLAN translation and QinQ.


The RTL8304E contains a 2K-entry address lookup table. Two 4-way associative hash algorithms avoid hash collisions and maintain forwarding performance. The 2K-entry table provides read/write access from the SMI interface, and each of the entries can be configured as a static entry that does not automatically age out and can only be controlled by the external management processor. For IGMP/MLD snooping application, each of the 2K entries can be configured as a multicast entry that indicates the matched packets will be forwarded to specific multi ports. For IEEE 802.1x application, each of the 2K entries can be configured as an authorized or unauthorized entry.

Maximum packet length can be 2047 bytes. Two types of independent storm filter are provided to filter packet storms, and an intelligent switch engine prevents Head-of-Line blocking problems. The filtering function is supported for IEEE 802.1D specified reserved multicast addresses (01-80-C2-00-00-02 and 01-80-C2-00-00-04 to 01-80-C2-00-00-0F).


The RTL8304E provides flexible LED functions for diagnostics. An externally managed processor can control the LEDs via SMI.


The RTL8304E supports Realtek’s Green Ethernet power saving mode, as well as Energy-Efficient Ethernet mode (EEE; defined in IEEE 802.3az) to minimize system power consumption. When the Green Ethernet Feature is enabled, the RTL8304E provides link-on and dynamic detection of cable length and dynamic adjustment of power required for the detected cable length. This feature provides high performance with minimum power consumption.


Energy-Efficient Ethernet (EEE) supports Low Power Idle Mode. When Low Power Idle Mode is enabled, systems on both sides of the link can disable portions of the functionality and save power during periods of low link utilization.


For whole system power saving, the RTL8304E supports the Wake-on-LAN (WOL) function and provides control signals to manage the system power based on the port linkage and the traffic loading of the CPU port.


To simplify the peripheral power circuit, the RTL8304E can use a low-cost PNP transistor to generate 1.8V from a 3.3V power supply.


    Basic Switching Functions
  • 4-port switch controller with 2 transceivers for 10Base-T and 100Base-TX and 2-port (T)MII/RMII
  • Non-blocking wire-speed reception and transmission and non-head-of-line-blocking forwarding
  • Complies with IEEE 802.3/802.3u auto-negotiation
  • Built-in high efficiency SRAM for packet buffer, with 2K-entry lookup table and two 4-way associative hash algorithms
  • 2047 byte maximum packet length
  • Flow control fully supported:
    • Half duplex: Back pressure flow control
    • Full duplex: IEEE 802.3x flow control

    Service Quality
  • Supports high performance QoS function on each port:
    • Supports 4-level priority queues
    • Weighted round robin service
    • Supports strict priority
    • Input/Output port bandwidth control
    • Queue based bandwidth control
    • ACL-based, 1Q-based, Port-based, DSCP-based, VID-based, IP address-based, and other types of priority assignments
  • Supports 16-entry ACL for advanced applications
  • Supports IEEE 802.1p Traffic Re-marking
  • Supports IGMP v1/v2/v3 and MLD v1/v2 snooping

    Security and Management
  • Supports MAC Limit
  • Supports Port Isolation
  • Supports IEEE 802.1x
  • Lookup Table is accessible via SMI
  • Supports 32-bit smart counter for per port RX/TX byte/packet count, collision counter, and error counter
  • Supports reserved control frame filtering
  • Supports advanced storm filtering
  • Supports Port Mirroring
  • Supports interrupt for CPU application
  • Supports proprietary CPU tag for traffic management
  • Supports SMI (Serial Management Interface) for programming and diagnostics
  • Optional EEPROM interface for configuration
    VLAN Functions
  • Supports up to 16 VLAN groups
  • Flexible 802.1Q port/tag-based VLAN
  • Supports VLAN translation
  • Supports QinQ
  • Leaky VLAN for ARP/unicast/IP multicast packets
  • Supports external processor to maintain greater than 16 VLAN groups

    Power Saving Functions
  • Green Ethernet Feature
  • Supports Energy-Efficient Ethernet (EEE) function (IEEE 802.3az)
  • Supports Wake-on-LAN (WOL)
  • Supports system power management based on link and CPU port traffic loading

    Diagnostic Functions
  • Supports IEEE 802.1D
  • Supports hardware loop detection function with LEDs and buzzer to indicate the existence of a loop
  • Supports cable diagnosis (RTCT function)
  • Supports MAC and PHY loopback function for diagnosis
  • Flexible LED indicators for link, activity, speed, as well as user defined LED output
    • Loop status indication
    • LEDs blink upon reset for LED diagnostics

    Other Features
  • Optional MDI/MDIX auto crossover for plug-and-play
  • Physical layer port Polarity Detection and Correction function
  • Robust baseline wander correction for improved 100Base-TX performance
  • 25MHz crystal or 3.3V/1.8V OSC input
  • Single 3.3V power input can be transformed to 1.8V via a low-cost external BJT transistor
  • Low power, 1.8/3.3V, 0.153µm CMOS technology
  • 64-pin QFN ‘Green’ package
  • HomePNA/HomePlug bridge solutions
  • Set-Top Box, TV, and VoIP applications


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