To allow the ports on a specified network module or voice/WAN interface card (VWIC) to use the network clock for timing, use the network-clock-participate command in global configuration mode. To restrict the device to use only its own clock signals, use the no form of this command:
network-clock-participate [slot slot-number | wic wic-slot | aim aim-slot-number]
no network-clock-participate [nm slot | wic wic-slot]
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This command is used for ATM segmentation and reassembly or digital signal processing and Cisco 3660, Cisco 3725, and Cisco 3745 routers. This command applies to any network module with T1/E1 controllers to provide clocks from a central source (MIX module for the Cisco 3660) to the network module and to the port on the network module. Then that port can be selected as the clock source with the network-clock-select command to supply clock to other ports or network modules that choose to participate in network clocking with the network-clock-participate command. This command synchronizes the clocks for two ports. On the Cisco 3700 series, you must use the network-clock-participate command and either the wic wic-slot keyword and argument or the slot slot-number keyword and argument.
2. network-clock-select
To name a source to provide timing for the network clock and to specify the selection priority for this clock source, use the network-clock-select command in global configuration mode. To cancel the network clock selection, use the no form of this command:
a. Cisco 2600 Series and Cisco 3660 with MIX Module
network-clock-select priority {t1 | e1} slot/port
no network-clock-select priority {t1 | e1} slot/port
b. Cisco MC3810
network-clock-select priority {serial 0 | system | bvm | controller}
no network-clock-select priority {serial 0 | system | bvm | controller}
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When an active clock source fails, the system chooses the next lower priority clock source specified by this command. When a higher-priority clock becomes available, the system automatically reselects the higher-priority clock source.
a. Cisco 2600 series, Cisco 3660, and Cisco 3700 series
This command is used on Cisco 2600 series and Cisco 2600XM with AIMs installed or on the Cisco 3660, Cisco 3725, or Cisco 3745 with Multiservice Interchange (MIX) modules installed. This command names a controller to provide clocking signals to the backplane, which then provides the names to all the network modules that are participating in network clocking.
b. Cisco MC3810
This command applies to Voice over Frame Relay, Voice over ATM, and Voice over HDLC on the Cisco MC3810. Use the network-clock-select command to establish the clock-selection priority when there are multiple sources of line (network) clocking in a Cisco MC3810. Possible sources of line clocking for the Cisco MC3810 are the BRI voice module (BVM), the multiflex trunk module (MFT), and a serial port configured for clock rate line.
