• Highly integrated, scalable switch fabric
• Single-chip bandwidth of up to 40 Gbps
• Supports two CSIX interfaces to line side
• Guaranteed Class of Service through the system – fabric
• Each CSIX supports 32, 64, or 128 bits at speeds up to 166
• HSTL Class 1 drivers
• Optional out-of-band flow control
• Four Egress Queues per CSIX interface
• 96-byte or 112-byte payloads
• Flexible fabric speedup and redundancy schemes
• Additional speedup to handle Cell Size + 1 byte case
• Link failure causes graceful reduction in speed-up
• Support for 16k Multicast Groups
• Full multicast group ID carries through the fabric
• Static or dynamic configurable VOQ cell buffering
interface chip (BCM8320) schedules based on destination,
while the fabric switch chip (BCM8332) schedules based on
source. QoS can be set on a source/destination basis with no
interference from other channels.
• Supports dual 10G interfaces in a single device.
• Excellent redundancy: all links that are used are always active.
N-1, N+1, and N≠2 redundancy modes are all supported – no
software intervention is necessary.
• Automatic link failure detection – no software intervention is
• Integrated SerDes provides a cost-effective and powerconscious solution.
• Single level or hierarchical Weighted Round Robin scheduling
• Proven high-speed 3.125 Gbps SerDes technology
BCM8320 System Architecture
The BCM83XX switch fabric chipset is a highly integrated scalable
switch fabric, consisting of the BCM8320 Fabric Interface chip and the
BCM8332 Switch chip. The BCM83XX switch fabric is ideal for these
• Metro packet aggregation
• Storage area networks
• Cellular packet infrastructure
• WAN core switching.
The BCM8320 supports up to two OC-192 CSIX ports per fabric
interface chip. Each CSIX interface allows Traffic management devices
supporting 32-bit- to 128-bit- wide interfaces to connect to the
BCM83XX switch fabric.
The BCM8320 has sixteen 3.125 Gbps SerDes links to the BCM8332
devices. These links are 8b/10b encoded, providing a true 2.5 Gbps data
link. The fabric can support up to a 4X speed-up if all the SerDes links
are used. Unlike standard crossbar architectures, the BCM83XX switch
fabric does not need speedup to maintain line rate traffic. However, a
selectable speedup is offered to handle cell size + 1 byte traffic cases as
well as compensation for embedded system level headers.
The BCM83XX switch fabric provides exceptional fault tolerance and
redundancy including the options of N–1, N+1 and N≠2 redundancy
modes. Any link failure causes a graceful degradation in speedup and
allows continuous operation during a failure or switch board
replacement. Link failure detection is performed in hardware and does
not require software intervention.
The BCM83XX switch fabric can support 16k multicast groups and
performs all replication in the switch fabric.
The proven 3.125 Gbps integrated SerDes provides a cost- and powereffective solution while minimizing the number of backplane
connections to the switch fabric.
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