Cisco AS5850 Руководство по установке оборудования - Страница 10
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Cisco AS5850 Chassis
Table 1-2
Chassis
Trunk
Type
24T1/T3
combination
24E1/STM1
Note
The universal gateway uses CT1, CE1, CT3, or STM1 trunk interfaces that terminate ISDN and modem
calls and break out individual calls from the appropriate telco services. Digital calls are terminated on
the trunk card high-level data link control (HDLC) controllers, and analog calls are terminated on the
universal ports on the trunk card, if available, or universal ports on another feature card. As a result, any
DS0 can be mapped to an onboard HDLC controller or any universal port. You can install multiple
ingress interface cards, which enables you to configure your systems as fully operative, port redundant,
or card redundant, depending on your specific needs.
Clock Management
The RSCs also provide clock and power control to the feature cards. Each RSC contains a block of logic,
referred to as the common logic, and system clocks. This block of logic can use a variety of sources to
generate the system timing, including a T1, E1,T3, STM1, or BITS input signal (accepts only T1 or E1)
from the BNC connector on the RSC front panel.
Only one common logic circuit is active at any one time, which is identified by the CLK (clock) LED on
the RSC front panel. The active common logic is user-selectable and is independent from each RSC. This
ensures that if an RSC needs replacing or if the slave RSC becomes the master, clocking remains stable.
The selected common logic should not be changed during normal operation unless related hardware
failure is suspected or diagnosed.
The configuration commands for the master clock specify the various clock sources and a priority for
each source. Together these commands define a list, ordered by priority, of the clock sources used to
generate the master clock. The prioritized list, configured on the router shelves, is passed to and stored
by the RSC providing the active clock. In the event of failure of the highest-priority clock source, the
RSC switches to the source with the next-highest priority.
With a split backplane, the clock sources can be configured on either of the RSCs. Typically a router
configures clock sources only from the slots that it owns; clock sources can be configured from other
slots, but they are ignored. On the universal gateway, all valid clock source configurations need to be
known to the RSC providing the clock, including the clock source configurations on the other RSC.
An error condition can arise if a clock input on one RSC is configured to have the same priority as a
clock input configured on the other RSC. However, the command is not rejected, because the values
configured on the other RSC may not be known. Warning messages are issued to both RSCs when this
Cisco AS5850 Universal Gateway Hardware Installation Guide
1-10
Maximum Number of Trunk Cards For ERSC (continued)
Non-Split Chassis
Total
Trunk
Total
Cards Per
324-port
Chassis
UPC
3 24T1
7
2 T3
1 STM1
7
2 24E1
Mixing CT1 or CT3 and CE1 or STM1 in the same chassis is not supported. If this
configuration guideline is violated, an error message appears on the RSC and the disallowed
card is shut down.
Split Chassis
Total
Total
Total
DS0s
Ports
Trunk
with
with
Cards Per
ERSC
ERSC
Chassis
3072
2700
1
3330
3240
—
Chapter 1
Cisco AS5850 Product Overview
Total
Total
DS0s
324-port
with
UPC
ERSC
1
1248
—
—
78-10573-06 0A
Total
Ports
with
ERSC
1512
—