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Cisco AS5850 Universal Gateway Hardware Installation Guide
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Chapter1 Cisco AS5850 Product Overview
CiscoAS5850 Chassis
condition is detected. Two clock inputs specified with identical priorities both go into the ordered list of
clock sources, but the one received first by the RSC providing the active clock is assigned a higher
priority.
The show chassis clocks command shows all configured clock sources, even those from un-owned trunk
cards. Only one RSC can provide the master clock; however, backup clock sources might need to be
configured for all trunk cards present (regardless of which RSC owns them).
Note If you need to OIR the RSC serving as the primary clock source with a split backplane configuration,
you will need to switch the primary clock source to the other RSC as described in Chapter 4,
“Maintenance” in the Cisco AS5850 Operations, Administration, Maintenance, and Provisioning
Guide, available online at:
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/as5850/sw_conf/5850oamp/
index.htm
Split Backplane
The split backplane configuration of the CiscoAS5850 platform increases bandwidth by using two
RSCs. The dual RSCs serve as the interfaces between the split Cisco AS5850 gateway and the external
network. Split backplane configuration requires two RSC cards. For more information on hardware and
software configuration needed for a split backplane configuration, refer to the CiscoAS5850 Operations,
Administration, Maintenance, and Provisioning Guide, available online at:
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/as5850/sw_conf/5850oamp/
index.htm
If your gateway contains two route switch controller (RSC) cards, you can configure your CiscoAS5850
into one of three modes: classic split, handover split, or route processor redundancy (RPR+).
•Classic-split mode (the default) maximizes system throughput by splitting slots between two RSCs.
Each RSC controls a certain set of slots (slots 0-5 are owned by the RSC in slot 6 and slots 8-13 are
owned by the RSC in slot 7) and operates as though slots other than those that it controls contain no
cards, because those cards are controlled by the other RSC. Configuration on each RSC affects only
the slots owned by that RSC. Calls on a failed RSC are lost, but calls on the functioning RSC
continue normally. Operating a CiscoAS5850 in classic-split mode is the same as having two
Cisco AS5850s, each with a separate set of cards.
•Handover-split mode maximizes system availability by allowing an RSC to automatically take
control of the slots, cards, and calls of the other RSC should that other RSC fail. Each RSC is
configured identically as appropriate for the full set of cards. During normal operation, both RSCs
are active, handling their own slots, cards, and calls just as in classic-split mode. Should an RSC
fail, the other RSC takes over control of the failed RSC's slots, goes into extra-load state, restarts
the failed RSC's cards, and handles newly arrived calls on those cards—although calls on the failed
RSC are lost at the moment of failure. The failed RSC, should it recover or be restarted, remains in
standby state until you instruct the active RSC to hand back its newly acquired slots to the standby
RSC. This is, in effect, split dial shelf with handover capability.
•In RPR+ mode, the standby RSC is fully initialized. The startup configuration is read, and the active
RSC dynamically synchronizes startup and running configuration changes to the standby RSC. This
means that the standby RSC need not be reloaded and reinitialized, and the feature cards are not reset
if the active RSC fails. Information synchronized to the standby RSC includes startup and running
configuration information and changes to the chassis state such as online insertion and removal
(OIR) of hardware. After switchover, new calls are being accepted in less than one second plus route
convergence time.