Cisco 12008, Руководство по установке и настройке, Страница: 66 / 382

Overview of the Cisco 12008
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide 1-44
Table 1-6 Switch Fabric Configurations
A minimally configured router (one with a single CSC and no SFCs) supports an OC-12
data rate, but provides no redundancy of CSC functions. Adding a second CSC to a system,
as well as the three optional SFCs, has the following effects:
•
Increases the router’s bandwidth from an OC-12 rate to an OC-48 rate.
•
Increases the number of planes of switch fabric available to the router from one to five
(with the fifth serving as a redundant plane in the event of failure of a CSC or SFC.
•
Provides full redundancy of CSC functions, such as the following:
— System clocking
— Resource allocation
— Scheduling
•
Provides full redundancy in the router’s fan power and alarm functions.
Clock and Scheduler Card
The CSC is a multi-function circuit board that can be installed in one or both of two
reserved slots (CSC0 and CSC1) in the middle of the upper card cage (see Figure 1-2). The
standard router configuration requires one CSC in either slot CSC0 or slot CSC1. If you
configure your router with a single CSC, it is recommended that you install it in CSC1.
Each CSC is mounted on its own card carrier and incorporates an onboard power supply
that takes the –48 VDC supplied by the backplane and converts it into the 3.3 VDC
operating voltage required by the card’s electronics.
Switch Fabric
Bandwidth Number of
CSCs Number of
SFCs Planes of Switch
Fabric
OC-12 nonredundant 1
1
1. A CSC is a required router component.
0 1
OC-12 redundant 2 0 2
OC-48 nonredundant 1 3 4
OC-48 redundant 2 3 5