Description
The MDS108 is a fully integrated 9-port Ethernet switch designed to support the low-cost requirements of unmanaged switch applications. The MDS108 provides features that are normally not associated with plug-and play technology, while not requiring an external processor to facilitate their utilization.
The MDS108 begins operating immediately at power-up, learning addresses automatically, and forwarding packets at full wire-speed to any of its eight output ports or the XLink expansion port. The default configuration allows operation without using an external EEPROM.
With an EEPROM to configure the device at power-up, the MDS108 provides flexible features: port trunking, port mirroring, port-based VLANs and (QoS) capabilities that are usually associated only with managed switches.
The built-in intelligence capabilites of the MDS108 allows it to recognize and offer packet prioritization using Zarlink Semiconductor’s QoS. 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.

FEATUREs
• 8 10/100 Mbps auto-negotiating RMII ports
• 1 10/100 Mbps auto-negotiating MII/serial port (port 8) that can be used as a WAN uplink or as a 9th port
• Operates stand-alone or can be cascaded with a second MDS108 to reach 16 ports
   - XLink expansion MII port (port 8)
   - Operates at 100/200/300/400 Mbps
• External I2C EEPROM for power-up configuration
   - Default mode allows operation without external EEPROM
• Up to 8 port-based VLANs
• Full wirespeed layer 2 switching on all ports (up to 2.679 M packets per second)
• Internal 1 K MAC address table
   - Auto address learning
   - Auto address aging
• Leading-edge Quality of Service (QoS) capabilities provided based on 802.1 p 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)
   - With flow control disabled, can drop packets during congestion using WRED
   - 2 levels of packet drop provided
• Provides port-based prioritization of packets on up to 4 ports
   - Input ports are defined to be high or low priority
   - Allows explicit identification of IP phone ports
• Supports both full and half duplex ports
• Ports 0 & 1 can be trunked to provide a 200 Mbps link to another switch or server
• Port 7 can be used to mirror traffic from the other 7 ports (0-6)
• Utilizes a single low-cost external pipelined, SyncBurst SRAM (SBRAM) for buffer memory
   - 256 KB or 512 KB (1 chip)
• Flow control capabilities
   - Provides back-pressure for half duplex
- 802.3x flow control for full duplex
• Supports external parallel port for configuration updates
• Special power-saving mode for inactive ports
• Ability to support WinSock 2.0 and Windows2000 smart applications
• Transmit delay control capabilities
   - Assures maximum delay (< 1 ms)
   - Supports mixed voice/data networks
• Optimized pin-out for easy board layout