MDS108

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-andplay 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.

The MDS108 can be used to create an 8-port unmanaged switch with one WAN router port by connecting a CPU
(ARM or MPC 850) to the additional MII port (port 8). 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 MDS108 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 MDS108 sustains full wirespeed switching on all 9 ports.The chip is packaged in a small 208 pin Plastic Quad Flat-Pak (PQFP) package.