Troubleshooting guide

MX2820 System Manual
1-12 61186003L1-1D
Clock Card
• P/N 1186004L1
The MX2820 Clock Card is a plug-in card which generates a timing signal synchronized to
either of two external BITS clock references. If both BITS clock references fail, the Clock Card
will meet SONET Minimum Clock (SMC) holdover requirements to produce the clock
reference. This signal may be used by any one of the MX2820 STS-1 MUX modules to
synchronize their STS-1 transmit signals. One Clock Card is required to support the STS-1
application when an external BITS clock reference is used. Two Clock Cards provide 1:1
redundancy in the MX2820 system.
Figure 1-5. MX2820 Clock Card, –48 VDC
The MX2820 Clock Card has the following Features:
• Provides a redundant SMC source with clock holdover to any MX2820 STS-1 MUX
• Communicates to the redundant Clock Card though an asynchronous data link directly
between the two cards
• Provides another direct link to the redundant card for protection management
• Maintains full duplex link to the SCU for management, alarm notification, and card
provisioning
• Displays status using a single front panel LED
• Operates over temperature range of: 0°C to +50°C (with fans)
• Supports downloading of FLASH program data to the active and protection card
simultaneously or individually
• Meets NEBS Level 3 requirements
• Interfaces to backplane via 24-pin Future Bus connector
• Supports TL1 and SNMP in the MX2820 system
1186004
CLK
ACT