®
MU9C1965A LANCAM MP
General Description
GENERAL DESCRIPTION
The MU9C1965A LANCAM® MP is a 1024 x 128-bit
content-addressable memory (CAM), featuring a 32-bit
wide interface. The wide comparand width allows the
LANCAM® MP to handle multiple protocols in a single
search table device.
entries are in the database. The ability to search data words
up to 128 bits wide allows large address spaces to be
searched rapidly and efficiently. A patented architecture
links each CAM entry to associated data and makes this
data available for use after a successful compare operation.
The MUSIC LANCAM® MP is ideal for address filtering
and translation applications in LAN and ATM switches and
routers that need the wide Comparand for Virtual LANs,
VC translation, or IPV6 address recognition. The 128-bit
CAM width is enough to include the DA, SA, Port ID, and
Virtual LAN ID for LAN switches, or DA, SA, and VC for
ATM switches. The LANCAM® MP is also well suited for
encryption, database accelerators, and image processing.
Content-addressable memories, also known as associative
memories, operate in the converse way to random access
memories (RAM). In a RAM, the input to the device is an
address and the output is the data stored at that address.
In a CAM, the input is a data sample and the output is a flag
to indicate a match and the address of the matching data. As
a result, a CAM searches large databases for matching data
in a short, constant time period, no matter how many
OPERATIONAL OVERVIEW
To use the LANCAM® MP, the user loads the data into the
Comparand register, which is automatically compared to all
valid CAM locations. The device then indicates whether or
not one or more of the valid CAM locations contains data
that matches the target data. The status of each CAM
location is determined by two validity bits at each memory
location. The two bits are encoded to render four validity
conditions: Valid, Skip, Empty, and Random access, as
shown in Table 1. The memory can be partitioned into
CAM and associated RAM segments on 32-bit boundaries,
but by using one of the two available mask registers, the
CAM/ RAM partitioning can be set at any arbitrary size
between zero and 128 bits.
cascading of additional LANCAM® MPs in a daisy chain
fashion extends the CAM memory depth for large
databases. Cascading requires no external logic. Loading
data to the Control, Comparand, and mask registers
automatically triggers a compare. Compares may also be
initiated by a command to the device. Associated RAM
data is available immediately after a successful compare
operation. The Status register reports the results of
compares including all flags and addresses. Two mask
registers are available and can be used in two different
ways: to mask comparisons or to mask data writes. The
random access validity type allows additional masks to be
stored in the CAM array where they may be retrieved
rapidly.
The LANCAM® MP’s internal data path is 128 bits wide
for rapid internal comparison and data movement. Vertical
A simple four-wire control interface and commands loaded
into the Instruction decoder control the device. A powerful
instruction set increases the control flexibility and
minimizes software overhead. Additionally, dedicated pins
for match and multiple match flags enhance performance
when the device is controlled by a state machine. These and
other features make the LANCAM® MP a powerful
associative memory that drastically reduces search delays.
Entry Type
Valid
Skip Bit
Empty Bit
0
0
1
1
0
1
0
1
Empty
Skip
RAM
Table 1: Entry types versus Validity Bits
2
Rev. 2
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