Introduction 1-19
Switch Software Description
Since the BPX switch is designed to be part of a larger communications network, it is capable of
synchronizing to higher-level network clocks as well as providing synchronization to lower-level
devices. Any network access input can be configured to synchronize the node. Any external T1 or
E1 input can also be configured to synchronize network timing. A clock output allows synchronizing
an adjacent IPX or IGX switch or other network device to the BPX switch and the network. In nodes
equipped with optional redundancy, the standby hardware is locked to the active hardware to
minimize system disruption during system switchovers.
The BPX switch does not accept clock from an IPX switch. The BPX Service Node can be
configured to select clock from the following sources:
• External (T1/E1)
• Line (DS3/E3)
• Internal
Switch Software Description
The Cisco WAN switching cell relay system software shares most core system software, as well as
a library of applications, between platforms. System software provides basic management and
control capabilities to each node.
IPX, IGX, and BPX node system software manages its own configuration, fault-isolation, failure
recovery, and other resources. Since no remote resources are involved, this ensures rapid response to
local problems. This distributed network control, rather than centralized control, provides increased
reliability.
Software among multiple nodes cooperates to perform network-wide functions such as trunk and
connection management. This multi-processor approach ensures rapid response with no single point
of failure. System software applications provide advanced features that may be installed and
configured as required by the user.
Some of the many software features are:
• Automatic routing of connections (AutoRoute feature).
• Various classes of service that may be assigned to each connection type (OptiClass feature).
• Bandwidth reservation on a time-of-day basis.
• Detection and control of network congestion with ABR with VSVD or ForeSight algorithms.
• Automatic self-testing of each component of the node.
• Automatic collecting and reporting of many network-wide statistics, such as trunk loading,
connection usage, and trunk error rates, as specified by the user.
The system software, configuration database, and the firmware that controls the operation of each
card type is resident in programmable memory and can be stored off-line in the Cisco StrataView
Plus NMS for immediate backup if necessary. This software and firmware is easily updated remotely
from a central site or from Customer Service, which reduces the likelihood of early obsolescence.
Connections and Connection Routing
The routing software supports the establishment, removal and rerouting of end-to-end channel
connections. There are three modes:
• Automatic Routing—the system software computes the best route for a connection.
• Manual Routing—the user can specify the route for a connection.
