BCM567X BOARDCOM [Broadcom Corporation.], BCM567X Datasheet - Page 15

• Manufacturer Part Number: BCM567X
• Description: A Scalable Approach to Gigabit Ethernet Switch Design
• Manufacturer: BOARDCOM [Broadcom Corporation.]

White Paper
BCM567x/BCM569x
06/27/02
I
D
NTERCONNECT
ECISIONS
For each Gigabit Ethernet switch form factor, designers require GE chips, physical-layer interfaces (including cabling and
connectors), a CPU management system, a power supply, and an operating system for activating and customizing features.
From there, some of the decisions the switch vendor/designer must make include whether the switch should be a single-chip
or multiple-chip solution, this largely depends on the number of ports to be supported. For multiple-chip solutions, designers
must decide what type of interconnect should be used to link the components and pass packets between them.
The choices of interconnects include cascade, matrix, and daisy chain options. StrataXGS cost-effectively supports all these
configurations, which are described in more detail below.
Cascade.
This is the simplest interconnect choice, most often used for low-end standalone/fixed systems. In this
configuration, chips are connected in a shared-ring fashion; the transmitter of one module is connected to the receiver of the
next module, and so on. The transmitter of the last module is connected to the receiver of the first module.
The merits of this interconnect choice are that it is the least expensive and uses few resources; ports, backplanes and other
resources are all shared.
One-way
packet flow
BCM5690
BCM5690
BCM5690
Figure 4: A Simplex Interconnect
Bro adco m Co rp or atio n
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