Understanding the Output from Diagnostic Commands
165
F I G U R E 4 . 5
Dual CyBus architecture
Just like the 7000 series router, the supported switching types for the 7500
series routers depend on the configuration and the IOS that is running on the
router. The basic switching paths that are supported by a 7500 series router
with the proper IOS are process switching, fast switching, and optimum
switching (optimum switching normally replaces fast switching).
When VIP2 boards are added, distributed switching is also supported.
Netflow and CEF (Cisco Express Forwarding) can also be implemented if
the proper IOS is used. These switching paths are discussed in detail in the
switching methods section.
Cisco 4000/2500 Series Architecture
These routers are not nearly as robust as the 7000 series, nor were they intended
to be. The 2500 series routers offer many interface configurations, but these con-
figurations are not modular, except the 2524 and 2525. The model used
depends on the network interfaces needed. The Cisco 4000 series is a modular
system, thus providing for more flexibility with network interfaces.
The key to these routers is that the interfaces do not have independent
processors like those in the 70
xx
/75
xx
series routers. This greatly
restricts the possible switching paths. The router's CPU must handle all
of the interfaces for the router.
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