DM8108
8 port 10/100M Fast Ethernet Switching Controller
2
Preliminary
Version: DM8108-DS-P02
November 25, 1999
Features
T Low cost Fast Ethernet Switching Controller.
O Provide packet switching functions between
eight
10/100Mbps, auto-negotiated on-chip Fast
Ethernet ports and a proprietary Full-duplex
Expansion port.
O Cascade max. 8 DM8108s without extra glue
logic for 64-port configuration.
T Incorporates three 802.3 compliant 10/100Mbps
Media Access Controllers
O Direct interface to MII (Media Independent
Interface)
O Half/Full Duplex Support for individual port (up-
to
200Mbps/port)
O IEEE 802.3 100Base-TX, T4.FX compatible
T Auto-negotiation supported through Serial MII
interface
T High-performance Distributed Switching Engine
O Performs packet forwarding and filtering at full
wire-speed
O 148,800 packets/sec. on each Ethernet port
T Direct support for packet buffering
O Glue-less interface with 1 or 2 Mbytes of SDRAM
(SGRAM)
O 32 bit memory bus configuration
O 66 Mhz – 90Mhz memory bus speed
O Up-to 1.1K buffers, 1536-byte each, allocated to
receive ports
T Support Store and Forward switching approach
O Low last-bit to first-bit out delay
O Allow mixed speed Ethernet packet switching
O Allow conversion between different protocols
T Flow control
O Support partitioning function
O Support back-pressure while lack of internal
resources
O Support 802.3x PAUSE function in full duplex
mode
O Support up to 4-port trunking for 800Mbps
bandwidth
T Advanced Address Learning and Searching
O Self learning mechanism
O Cache 128 address entries internally
O Record up-to 16K Uni-cast MAC addresses and
unlimited Multicast and Broadcast addresses
O Automatic aging scheme
O Broadcast filtering rate control
T Expansion Bus
O Up-to 8 SW devices can be cascaded via
expansion bus without extra logic
O Full duplex mode transfer
O Less Bus overhead
O Automatic flow control
T Complete status report to a simple LED interface
T Suitable for low cost Switch market to replace
Hub
T 0.35 m process, 3.3V with 5V tolerant I/O
T 208-pin PQFP package
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