Cisco Cisco ONS 15454 SONET Multiservice Provisioning Platform (MSPP) 故障排查指南
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Introduction
There are several common issues that arise when you configure timing on the Cisco ONS 15454.
This document explains these issues and provides an example of a timing best practice that you can
use in a four-node ONS 15454 network. This document covers these areas:
This document explains these issues and provides an example of a timing best practice that you can
use in a four-node ONS 15454 network. This document covers these areas:
BITS backplane pins for external timing references
Timing alarm types
Timing concepts
Simple Timing Topology Lab setup
Best Practice Timing Topology Lab setup
Timing configuration screen for external timing
Alarms screen when configuring external timing
Timing configuration screen for line timing
Alarms screen when configuring line timing
Timing topology changes when a ring is broken
Using alarm screens to explain timing topology resynchronization
Using alarm screens to explain timing topology recovery (reversion)
Use this document with the
Setting Up ONS 15454 Timing
section of the Cisco ONS 15454 User
Documentation. The lab setup used is based on the network shown in the user documentation.
However, this document can also be used as a standalone configuration and troubleshooting guide.
However, this document can also be used as a standalone configuration and troubleshooting guide.
Note: It is necessary to set the Synchronous Optical Network (SONET) timing parameters for each
ONS 15454. Timing can be set to either the external, line, or mixed node. In most ONS 15454
networks, one node is set to external, and the other nodes are set to line. The external node accepts
its timing from a Building Integrated Timing Supply (BITS) source wired to the BITS backplane
pins. The BITS source, in turn, gets its timing from a Primary Reference Source (PRS), such as a
Stratum 1 (ST1) clock or Global Positioning Satellite (GPS) signal. The line nodes accept their
timing from optical carrier cards. For protection, up to three timing references can be identified.
These are typically two BITS level or line-level sources and an internal reference. The internal
reference is the Stratum 3 (ST3) clock provided on every ONS 15454 Timing Communication and
Control (TCC) card.
ONS 15454. Timing can be set to either the external, line, or mixed node. In most ONS 15454
networks, one node is set to external, and the other nodes are set to line. The external node accepts
its timing from a Building Integrated Timing Supply (BITS) source wired to the BITS backplane
pins. The BITS source, in turn, gets its timing from a Primary Reference Source (PRS), such as a
Stratum 1 (ST1) clock or Global Positioning Satellite (GPS) signal. The line nodes accept their
timing from optical carrier cards. For protection, up to three timing references can be identified.
These are typically two BITS level or line-level sources and an internal reference. The internal
reference is the Stratum 3 (ST3) clock provided on every ONS 15454 Timing Communication and
Control (TCC) card.
Table 1
shows the clock accuracy and why we are an ST3. When the ONS 15454 goes into holdover
Page 2 of 44
Cisco - ONS 15454 Timing Issues
12/29/2004
http://www.cisco.com/warp/customer/127/Timing/15454_timingissues.html