MDS105

• 4 10/100 Mbps auto-negotiating RMII ports
• 1 10/100 Mbps auto-negotiating MII/serial port (Port 4) that can be used as a WAN uplink or as a  5th port
• External I2C EEPROM for power-up configuration - Default mode allows operation without external EEPROM
• Up to 4 port-based VLANs
• Full wire-speed layer 2 switching on all ports (up to 1.448 M packets per second)
• Internal 1 k MAC address table - Auto address learning - Auto address aging
• Leading edge QoS capabilities provided based on 802.1p and IP TOS/DS field - 2 queues per output port - Packet scheduling based on Weighted Round- Robin (WRR) and Weighted Random Early Detection/Drop (WRED) - Without flow control can drop packets during congestion using WRED  - 2 levels of packet drop provided
• Supports both Full/Half duplex ports
• Supports external parallel port for configuration updates
• Port 3 can be used to mirror traffic from the other 3 ports (0-2)
• Provides port-based prioritization of packets on up to 2 ports (0-1) - Input ports are defined to be high or low priority - Allows explicit identification of IP Phone ports
• Ports 0 & 1 can be trunked to provide a 200 Mbps link to another switch or server
• Utilizes a single low-cost external Pipelined, SyncBurst SRAM (SBRAM) for buffer memory - 256 k bytes or 512 k bytes (1 chip)
• Flow Control capabilities - Provides back pressure for half duplex - 802.3x flow control for full duplex
• Special power-saving mode for inactive ports
• Ability to support WinSock2.0 and Windows2000 smart applications
• Transmit delay control capabilities  - Provides maximum delay guarantee (<1 ms) - Supports mixed voice-data networks
• Optimized pin-out for easy board layout

The MDS105 is a fully integrated 5 port Ethernet switch designed to support the low-cost requirements of unmanaged switch applications. It provides features that are normally not associated with plug-andplay technology, while not requiring an external processor to facilitate their utilization.

The MDS105 begins operating immediately at power-up, learning addresses automatically and forwarding packets at full wire-speed to any of its four output ports or the uplink expansion port. The default configuration allows operation without using an external EEPROM.

With an EEPROM to configure the device at power-up, however, the MDS105 provides flexible features: port trunking, port mirroring, port-based VLANs, and Quality of Service (QoS) capabilities that are usually associated only with managed switches. The built-in intelligence of the MDS105 allows it to recognize and offer packet prioritization using Zarlink's QoS scheme. Packets are prioritized based upon their layer 2 VLAN priority tag or the layer 3 Type-Of- Service/Differentiated Services (TOS/DS) field. This priority can be defined as transmit and/or drop priority. It can be used to create a 4 port unmanaged switch with one WAN router port by connecting a CPU (ARM or MPC 850) to the additional MII port (Port 4). The only external components needed are the physical layer

transceivers and a single SBRAM, resulting in a low total system cost. Designed to support the requirements of converging networks, the MDS105 utilizes a power conserving architecture. To further enhance this power management, the chip automatically detects when a switch port is not being utilized, and turns off the logic associated with that port, thereby saving power and reducing the current load on the switch power supply. Operating at 66 MHz internally, and with a 66 MHz interface to the external SBRAM, the MDS105 sustains full wirespeed switching on all 5 ports. The chip is packaged in a small 208 pin Plastic Quad Flat-Pak (PQFP) package.