INDEX
ADVANCED INFORMATION
MX98748
8-Port Dual-Speed Segment-Bridged Repeater Controller
1. Features
• Fully integrate 8-port hub controller with 4-port switch
controller, 2 (Fast) Ethernet switch ports used inter-
nally for bridging 10M and 100M segments, and addi-
tional 2 (Fast) Ethernet switch ports used for high-
throughput user connections.
• The user connection ports of 8 hub ports plus 2 switch
ports can be configured to 7 hub ports plus 3 switch
ports if all hub connection interfaces follow single
specific standard, namely Ethernet or Fast Ethernet.
• Support independent 10Mbps and 100Mbps Ethernet
operation segments in hub portion.
• Automatically connect each port to specific segment,
namely 10M or 100M by its data flow rate without user
intervention.
• Two expansion bus in backplane, one for 10Mbps
operation and one for 100Mbps operation are used to
cascade other controllers or stack hub devices.
• Integrate LED drivers for at-a-glance operation status
monitoring.
• Single 64K x 32 SSRAM memory part used as data
buffer and filtering database for 2-port switch opera-
tion.
• 274-pin BGA.
2. Description
MX98748 is an 8-port dual-speed segment-bridged hub
controller plus 2 additional (Fast) Ethernet switch ports
to provide system vendors a cost-effective chip solution
on work-group segment-switched, stack hub devices.
Works with (quad) auto-detect PHY components,
MX98748 builds separate 10Mbps repeater state ma-
chine and 100Mbps repeater state machine inside to
supports either conventional Ethernet or Fast Ethernet
operation on each MII port. Depending on data rate,
controller automatically hooks each port to the specific
segment such that the 10M ports operate in one do-
main and 100M ports in another domain, they do not
interfere mutually. Controller provides two expansion
ports (or inter-repeater buses) for stack hub applica-
tion, one for 10Mbps cascading and one for 100Mbps
cascading. Up to 31 controllers can be chained together
in a stack hub system.
A 4-port switch is built-in to store-and-forward frames
between 10M segment and 100M segment and another
2 high-throughput sources. Two extra embedded MII
ports are utilized as connection points between (10M
and 100M) repeaters and switching ports. The switch
auto-learns address information in stack hub system,
maximum 248 search entries within filtering table in fully-
stacked hub system. Once frame transmitted in repeater
domains, switch verifies whether source host and desti-
nation host reside on the same segment or different
ones. Suppose two host are on same segment, the frame
received on switch port is filtered. Otherwise the received
frame will be relayed to the other segment. A single 64K
x 32 SSRAM memory component is recommended to
be used for storage of received frames and filtering table.
Suppose all the user connection interfaces on hub ports
follow single specific standard, namely Ethernet or Fast
Ethernet. The user traffic is focused on a certain seg-
ment such that the internal bridging function is not nec-
essary. Via configuration pins the attribute of hub port
which is numbered 6 or 7 can be changed to (Fast)
Ethernet switch to utilize the power of integrated 4-port
switch controller most.
LED drivers are integrated per hub port for operation
status monitoring. System vendors could implement LED
matrix display on front panel for at-a-glance monitoring.
Individual LED could indicate "Speed" (10Mbps or
100Mbps rate), "Collision", "Link", "Partition", and "Utili-
zation".
P/N:PM0583
REV. 0.0, OCT. 20, 1998
1
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