Network Synchronization - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Network Synchronization

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The Cisco WAN Switching Command Reference contains detailed information about the use of BPX
switch commands.
Network Synchronization
Cisco WAN switching cell relay networks use a fault-tolerant network synchronization method of the
type recommended for Integrated Services Digital Network (ISDN). You can select any circuit line,
trunk, or an external clock input to provide a primary network clock. Any line can be configured as a
secondary clock source in the event that the primary clock source fails.
All nodes are equipped with a redundant, high-stability internal oscillator that meets Stratum 3 (BPX)
or Stratum 4 requirements. Each node keeps a map of the network's clocking hierarchy. The network
clock source is automatically switched in the event of failure of a clock source.
There is less likelihood of a loss of data resulting from re-frames that occur during a clock switchover
or other momentary disruption of network clocking with cell-based networks than there is with
traditional TDM networks. Data is held in buffers and packets are not sent until a trunk has regained
frame synchronism to prevent loss of data.
Cisco BPX 8600 Series Installation and Configuration
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Enabling cost-based route selection automatically enables cache usage. Disabling cost-based route
selection automatically disables cache usage. Cache usage may also be independently enabled or
disabled.
cnftrk
Configures the administrative cost for a trunk. Both physical and virtual trunks have the cost
attribute. Each trunk has a cost ranging from 1 (lowest) to 50 (highest). The default cost is 10 upon
trunk activation.
The cost can be configured from either end of the trunk. The cost can be changed before or after
the trunk has been added to the network. The cost can also be changed after connections have been
routed over the trunk. Any cost change is updated network-wide. Every node in the network stores
the cost of every trunk in the network. This knowledge is required for successful source-based
routing.
cnfrtcost
Configures the cost cap for a connection. This command is valid only at the node where the
connection is added.
cnfsysparm
Configures the delay cost cap for all delay sensitive connections in the network.
dspcon
Displays the maximum and current costs for a connection route
dspload
Displays the administrative cost and queue delay for a network trunk
dsprts
Displays the current costs for all connection routes
dsptrkcnf
Displays the configured cost of a trunk
Chapter 1 The BPX Switch: Functional Overview
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001