Cisco ONS 15327, User Documentation

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Cisco ONS 15327 User Documentation, R3.3
June 2002
Chapter 3 Node Setup
Setting Up ONS 15327 Timing
Procedure: Set Up ONS 15327 Timing
Step 1
From the CTC node view, click the Provisioning > Timing tabs ( Figure 3-5 ).
Step 2 In the General Timing section, complete the following information:
•
Timing Mode —Set to External if the ONS 15327 derives its timing from a BITS source wired to the
BITS port on the MIC; set to Line if timing is derived from an OC-N card that is optically connected
to the timing node. A third option, Mixed, allows you to set external and line timing references.
(Because Mixed timing may cause timing loops, Cisco does not recommend its use. Use this mode
with care.)
• SSM Message Set —Choose the message set level supported by your network. If a Generation 1 node
receives a Generation 2 message, the message will be mapped down to the next available Generation
1. For example, an ST3E message becomes an ST3.
•
Quality of RES —If your timing source supports the reserved S1 byte, you set the timing quality here.
(Most timing sources do not use RES.) Qualities are displayed in descending quality order as ranges.
For example, ST3<RES<ST2 means the timing reference is higher than a Stratum 3 and lower than
a Stratum 2. See
Table 3-4 and Table 3-5 for more information.
•
Revertive —If checked, the ONS 15327 reverts to a primary reference source after the conditions that
caused it to switch to a secondary timing reference are corrected.
•
Revertive Time —If Revertive is checked, indicate the amount of time the ONS 15327 will wait
before reverting back to its primary timing source.
ST3 4 Stratum 3
SMC 5 SONET minimum clock
ST4 6 Stratum 4
DUS 7 Do not use for timing synchronization
RES Reserved; quality level set by user
Table 3-5 SSM Generation 2 Message Set
Message Quality Description
PRS 1 Primary reference source - Stratum 1
STU 2 Sync traceability unknown
ST2 3 Stratum 2
TNC 4 Transit node clock
ST3E 5 Stratum 3E
ST3 6 Stratum 3
SMC 7 SONET minimum clock
ST4 8 Stratum 4
DUS 9 Do not use for timing synchronization
RES Reserved; quality level set by user
Table 3-4 SSM Generation 1 Message Set (continued)
Message Quality Description