7705 SAR Interfaces
484
Interface Configuration Guide
3HE 11011 AAAC TQZZA Edition: 01
3.13.2.26 DS3 and E3 Commands
clock-source
Syntax clock-source {loop-timed | node-timed | differential | free-run}
Context config>port>tdm>ds3
config>port>tdm>e3
Description This command specifies the clock source to be used for the link transmit timing.
The clock source setting also determines the node sync reference if the port is configured as
one of the node synchronization references (config>system>sync-if-timing>{ref1 | ref2}>
source-port command). Refer to the 7705 SAR Basic System Configuration Guide, “Node
Timing”, for more information.
Default node-timed (for the 4-port DS3/E3 Adapter card)
loop-timed (for all other applicable adapter cards)
Parameters loop-timed — the link recovers the clock from the received data stream
node-timed — the link uses the internal clock when transmitting data (this parameter
does not apply to the 2-port OC3/STM1 Channelized Adapter card)
differential — clocking is derived from a common clock compared to differential clock
recovery (DCR) data in the RTP header in the TDM PW overhead. DCR must also
be enabled on the relevant card, module, or chassis with the clock-mode command.
This parameter applies only to DS3/E3 ports on the 4-port DS3/E3 Adapter card.
free-run — timing source is from its own clock, not an external timing source (this
parameter does not apply to the 4-port DS3/E3 Adapter card)
crc
Syntax crc {16 | 32}
Context config>port>tdm>ds3
config>port>tdm>e3
Description This command configures the precision of the cyclic redundancy check (CRC). Non-ATM
ports support a 16-bit checksum and ATM ports support a 32-bit checksum. CRC applies to
PPP applications only on the 2-port OC3/STM1 Channelized Adapter card and 4-port DS3/E3
Adapter card.
Default 16 (non-ATM ports)
32 (ATM ports)
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