DM8108
8 port 10/100M Fast Ethernet Switching Controller
Preliminary
1
Version: DM8108-DS-P02
November 25, 1999
General Description
The DM8108 is an 8 port 10/100Mbit/s nonblocking
Ethernet switch with on-chip address-lookup engine. The
DM8108 provides a low-cost, high-performance switch
solution with PHYs and single SGRAM.
The DM8108 provides eight 10/100Mbit/s Fast Ethernet
interface. In half-duplex mode, all ports support back-
pressure capability to reduce the risk of data loss for a long
burst of activity. In the full-duplex mode of operation, the
device uses IEEE std. 802.3 frame-based pause protocol
for flow control. With full-duplex capability, port 0 – 7 support
1.6Gbit/s aggregate bandwidth connections. The DM8108
also supports port trunking/load balancing on the
10/100Mbit ports. This can be used to group ports on inter-
switch links to increase the effective bandwidth between the
systems.
The internal address-lookup engine supports up to 16.25K
unicast and unlimited multicast and broadcast addresses.
This engine performs destination and source addresses
book-keeping and comparison which also forwards
unknown destination address packets to all ports.
The DM8108 is fabricated with a .35um technology.
Working at 3.3V, the inputs are 5V tolerant and the outputs
are capable of directly driving at TTL levels.
Block Diagram
Expansion
Address
Learning
MEM
Controller
LED Control
Unit
Switching
Engine
Control &
Status