MDS108
Unmanaged 9-Port 10/100 Mbps
Ethernet Switch
Data Sheet
Features
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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
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XLink expansion MII port (port 8)
Operates at 100/200/300/400 Mbps
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Default mode allows operation without external
EEPROM
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November 2003
Ordering Information
MDS108AL
208 Pin PQFP
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-40°C to +85°C
Input ports are defined to be high or low priority
Allows explicit identification of IP phone ports
External I
2
C EEPROM for power-up configuration
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
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256 KB or 512 KB (1 chip)
Provides back-pressure for half duplex
802.3x flow control for full duplex
Flow control capabilities
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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
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Auto address learning
Auto address aging
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Leading-edge Quality of Service (QoS)
capabilities provided based on 802.1 p and IP
TOS/DS field
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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
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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
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Assures maximum delay (< 1 ms)
Supports mixed voice/data networks
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Provides port-based prioritization of packets on
up to 4 ports
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Optimized pin-out for easy board layout
Figure 1 - System Block Diagram
1
Zarlink Semiconductor Inc.
Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.
Copyright 2003, Zarlink Semiconductor Inc. All Rights Reserved.
MDS108
Description
Data Sheet
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.
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 wire-
speed switching on all 9 ports.
The chip is packaged in a small 208 pin Plastic Quad Flat-Pak (PQFP) package.
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Zarlink Semiconductor Inc.
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