®
S E M I C O N D U C T O R S
MUSIC
I
MU9C8248
FDDI SRT Interface
PRELIMINARY DATA SHEET
DISTINCTIVE CHARACTERISTICS
• High-speed FDDI Source Routing and Transparent
Bridging address filter supports up to sixteen ports
• Glue-free operation with the MUSIC MU9C1480 LANCAM
and AMD, National Semiconductor, and Motorola FDDI
chip sets
• Configurable for both Motorola and Intel processor
addressing modes
• Complies with the ISO 9314 standard for FDDI
• 64-entry Instruction Buffer holds up to six down-
loadable filtering and purging routines
• 64-entry Data Buffer or internal FIFO
• Automatic selection of Source Routing or Transparent
filtering routines based on Transceiver output data
• Supplies proper XDAMAT, XSAMAT, SRMAT, ABORT,
and CIP signals to the FDDI chip sets
• Selectable filtering options for each frame type
• Checks validity of Routing Information Field
• TTL-compatible interfaces
• Manufactured in CMOS technology
• Available in 100-pin PQFP package
GENERAL DESCRIPTION
The MU9C8248 is a Source Routing Transparent (SRT) Interface to the
MUSIC Semiconductors LANCAM for use in FDDI LAN Bridges and
Brouters. This interface operates in accordance with ISO standards
while supporting address filtering rates up to 500,000 frames/sec for
minimum-length frames.
The MU9C8248 has five interfaces to provide “glue-free” address
filtering. The Transceiver interface monitors receive data between the
Physical Layer device and the MAC and determines whether to filter
according to Source Routing or Transparent Bridging standards. The
MAC interface supplies signals to instruct the FDDI chip set to reject or
copy a frame. The LANCAM interface controls the companion
LANCAM(s) for Transparent filtering. The Host Processor interface
allows direct initialization of the MU9C8248, and downloading of the
filtering and purging routines. The FIFO interface outputs new
addresses received from the FDDI network.
The MU9C8248 can choose to copy or reject a frame depending on the
frame's DA, RIF, and/or the frame type (MAC, LLC, or Reserved), and
can perform multiple validity checks within the Routing Information
Field (RIF), including general checks on every Routing Control Field
(RCF) as well as multiple frame related checks.
The internal RAM can store up to 64 instructions at initialization for the
LANCAM to execute matching, learning, aging, and purging operations.
Up to six routines can be stored here and started by the network or the
Node Processor. Internal arbitration prioritizes execution of instructions
by the LANCAM. A second internal RAM, which contains 64 16-bit
words, is used for data buffering operations or as an internal FIFO.
With sixteen Ring-Bridge-Ring number combinations stored internally,
the MU9C8248 is very well suited to operate as an address filter in
multi-port Source Routing Bridge/Brouter environments.
BLOCK DIAGRAM
RCDAT7-
RCDAT0
RCCONT,
RCCONTA
RCCONTB
XDAMAT
XSAMAT
PARITY
SRMAT
ABORT
CIP
8
TRANSCEIVER
INTERFACE
MAC
INTERFACE
/INT
6
TRANSPARENT
BRIDGING BLOCK
LANCAM INTERFACE
HOST PROCESSOR
INTERFACE
16
A5-A0
D15-D0
ALE, SRNW
/CS
/RS, /LDS
/WS, /UDS
/HBRDY
/HBEN
/HBDIR
/RESET
8
/FULL, /EMPTY
DF7-DF0
MCLK
/WF
DFC
/FFI
/INTEL
DCLK
STRIP
STOP STRIP
DQ15-DQ0
16
/E
/W
/CM
/EC
/MI
/FI
SOURCE ROUTING
BLOCK
INSTRUCTION
BUFFER
ARBITER
MUSIC is a trademark of MUSIC Semiconductors. LANCAM, the MUSIC logo, and the phrase “MUSIC Semiconductors” are registered trademarks of
MUSIC Semiconductors. AMD is a registered trademark of Advanced Micro Devices, Inc. National Semiconductor is a registered trademark of National
Semiconductor Corporation. Motorola is a registered trademark of Motorola, Inc. Intel is a registered trademark of Intel Corporation.
15 April 1997 Rev. 2.5
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