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The BlackDiamond Systems
Advanced System Diagnostics and Troubleshooting Guide 19
packet memory for temporary storage. Based on the information in memory, such as the FDB, the
address filtering and queue management ASIC makes a forwarding decision. If the next hop is a local
port (on the same module), the packet is forwarded to the external MAC and PHY for the exit port. If
the packet is destined for another module (as either slow path traffic or fast path traffic), the packet is
transferred to the internal MAC and then on to the MSM (CPU).
All I/O modules share the management bus on the backplane, and use it to communicate to each other
and to the MSMs.
Management Switch Modules
As its name indicates, the Management Switch Fabric Module (MSM) serves a dual role in the system: it
is equipped to act as the internal switch fabric for data that is being transferred between I/O modules
in the chassis, and to handle the upper-layer processing and system management functions for the
switch. (See
Figure 4 .)
Figure 4: BlackDiamond MSM architecture (MSM64 i shown)
An MSM is equipped with the following hardware components: CPU subsystem (dual CPUs, DRAM,
NVRAM, flash memory, and PCMCIA slot) and switch fabric subsystem (Quake ASICs, OTP, PQ, and
VPST RAM, packet memory and FDB SRAM, Twister ASICs, PBUS, and MAC ASICs).
AFQM
ASIC
256 MB
DRAM
OTP RAM
MAC
MAC
MAC
MAC
MAC
MAC
MAC
CPU
CPU
PCMCI
Slot
MAC
PQ RAM
VPST RAM
Flash
NVRAM
AFQM
ASIC
OTP RAM
PQ RAM
VPST RAM
SRAM (Packet Mem + FDB)
DN_027C
SE
ASIC
SE
ASIC
SE
ASIC
SE
ASIC
SE
ASIC
SE
ASIC
SE
ASIC
SE
ASIC
PBUS
CPU
Subsystem