Cisco Systems 15310-MA manual Timing

CHAPT ER
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Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2
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6
Timing
This chapter provides information about Cisco ONS 15310-MA SDH timing. To provision timing, refer
to the Cisco ONS 15310-MA SDH Procedure Guide.
Chapter topics include:
• 6.1 Timing Parameters, page 6-1
• 6.2 Network Timing, page 6-2
• 6.3 Synchronization Status Messaging, page 6-2
6.1 Timing Parameters
Node Timing parameters must be set for each ONS 15310-MA SDH. Each ONS 15310-MA SDH
independently accepts its timing reference from one of three sources:
• The building integrated timing supply (BITS) port on the ONS 15310-MA SDH.
• An STM-N/E1 port on the ONS 15310-MA SDH. The port is connected to a node that receives
timing through a BITS source.
• The internal G.813/SMC clock on the CTX card.
You can set ONS 15310-MA SDH timing to one of three modes: external, line, or mixed. If timing is
coming from the BITS port, set ONS 15310-MA SDH timing to external. If the timing comes from an
STM-N and E1 port, set the timing to line. Typical ONS 15310-MA SDH networks have the following
timing configurations:
• One node is set to external. The external node derives its timing from a BITS source wired to the
CTX port. The BITS source derives its timing from a primary reference source (PRS) such as a
Stratum 1 clock or global positioning satellite (GPS) signal.
• The other nodes are set to line. The line nodes derive timing from the externally timed node through
the E1 port and STMN trunk (span) port.
You can set three timing references for each ONS 15310-MA SDH. The first two references are typically
one BITS-level sources, or two line-level sources optically connected to a node with a BITS source. The
third reference is usually assigned to the internal clock provided on every ONS 15310-MA SDH CTX
card. However, if you assign all three references to other timing sources, the internal clock is always
available as a backup timing reference. The internal clock is a SETS (G.813) in ONS 15310-MA SDH.
If a node becomes isolated, timing is maintained at the SETS level.
The CTC Maintenance > Timing > Report tabs show current timing information for an ONS 15310-MA
SDH, including the timing mode, clock state and status, switch type, and reference data.