Specifications

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Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 2 General Troubleshooting
2.4.3 Unable to Create Circuit From DS-3 Card to DS3XM-6 Card
A circuit cannot be created from a DS-3 card to a DS3XM-6 card because the cards have different
functions. DS3XM-6 converts each of its six DS-3 interfaces into 28 DS-1s for cross-connection through
the network. Thus you can create a circuit from a DS3XM-6 card to a DS-1 card, but not from a
DS3XM-6 card to a DS-3 card. These differences are evident in the STS path overhead. The DS-3 card
uses asynchronous mapping for DS-3, which is indicated by the C2 byte in the STS path overhead that
has a hex code of 04. A DS3XM-6 has a VT payload with a C2 hex value of 02.
Note You can find instructions for creating circuits in the Cisco ONS 15454 Installation and Operations
Guide.
2.4.4 DS3 Card Does Not Report AIS-P From External Equipment
A DS3-12/DS3N-12/DS3-12E/DS3N-12E card does not report STS AIS-P from the external
equipment/line side. The card is functioning as designed. This card terminates the port signal at the
backplane so STS AIS-P is not reported from the external equipment/line side.
DS3-12/DS3N-12E cards do have DS3 header monitoring functionality, which allows you to view
performance monitoring (PM) on the DS3 path. Nevertheless, you cannot view AIS-P on the STS path.
For more information on the PM capabilities of the DS3-12E/DS3N-12E cards, refer to the Cisco ONS
15454 Installation and Operations Guide.
2.4.5 OC-3 and DCC Limitations
For an explanation of OC-3 and DCC limitations, see the DCC Tunnels section of the Cisco ONS 15454
Installation and Operations Guide.
2.4.6 ONS 15454 Switches Timing Reference
Timing references switch when one or more of the following problems occur:
• The optical or BITS input is receiving LOS, LOF, or AIS signals from another node.
• The optical or BITS input is not functioning.
• Sync Status Messaging (SSM) message is set to Don’t Use for Sync (DUS).
• SSM indicates a Stratum 3 or lower clock quality.
• The input frequency is off by more than 15 ppm.
• The input clock wanders and has more than three slips in 30 seconds.
• A bad timing reference existed for at least two minutes.
The ONS 15454 internal clock operates at a Stratum 3 level of accuracy. This gives the ONS 15454 a
free-running synchronization accuracy of ±
4.6 ppm and a holdover stability of less than 255 slips in the
first 24 hours or 3.7x10-
7
/day, including temperature.
ONS 15454 free running synchronization relies on the Stratum 3 internal clock. Over an extended time
period, using a higher quality Stratum 1 or Stratum 2 timing source results in fewer timing slips than a
lower quality Stratum 3 timing source.