Cisco BPX 8650, Installation And Configuration Manual

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Cisco BPX 8600 Series Installation and Configuration
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Chapter 1 The BPX Switch: Functional Overview
Switch Software Description
•
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.
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 WAN Manager NMS
for immediate backup if necessary. This software and firmware is easily updated remotely from a central
site or from Cisco 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. The following are the three routing modes:
•
Automatic routing—Allows the system software to compute the best route for a connection.
• Manual routing—Specifies the route for a connection.
•
Alternate routing—Allows the system software to automatically reroute a failed connection.
The system software uses the following criteria when it establishes an automatic route for a connection:
•
Selects the most direct route between two nodes.
• Selects unloaded lines that can handle the increased traffic of additional connections.
•
Takes into consideration user-configured connection restrictions, for example, whether or not the
connection is restricted to terrestrial lines or can include satellite hops or routes configured for route
diversity.
When a node reroutes a connection, it uses these criteria and also looks at the priority that has been
assigned and any user-configured routing restrictions. The node analyzes trunk loading to determine the
number of cells or packets the network can successfully deliver. Within these loading limits, the node
can calculate the maximum combination allowed on a network trunk of each type of connection, for
example, synchronous data, ATM traffic, Frame Relay data, multimedia data, voice, and compressed
voice.
Network-wide T3, E3, OC-3, or OC-12 connections are supported between BPX switches terminating
ATM user devices on the BPX switch UNI ports. The connections are routed using the virtual path or
virtual circuit addressing fields in the ATM cell header.
Narrowband connections are routed over high-speed ATM backbone networks built on BPX broadband
switches. FastPacket addresses are translated into ATM cell addresses that are then used to route the
connections between BPX switches, and to ATM networks with mixed vendor ATM switches. Routing
algorithms select broadband links only, which avoids narrowband nodes that could create a choke point.
Connection Routing Groups
The rerouting mechanism ensures that connections are presorted in order of cell loading when they are
added. Each routing group contains connections with loading in a particular range. The group containing
the connections with the largest cell loadings is rerouted first, and subsequent groups are then rerouted
on down to the last group that contains connections with the smallest cell loadings.