•
SPA-1CHOC3-CE-ATM, SPA-2CHT3-CE-ATM, or SPA-24CHT1-CE-ATM can be used as the clock
source.
•
The clock must be the same as that used by the router as the network clock. Any pseudowire can carry
the clock.
•
The minimum bundle size of the CEM pseudowires on the network that delivers robust clock recovery
is 4 DS0s.
•
The minimum packet size of the CEM pseudowires on the network that delivers robust clock recovery
is 64 bytes.
•
Effective from Cisco IOS XE Release 3.6.0S, the SPA-2CHT3-CE-ATM supports adaptive clocking
for the CEM mode. The SPA-2CHT3-CE-ATM does not support Out-of-Band (OOB) clocking in the
CEM mode due to lack of hardware support.
Differential Clock Recovery
•
The SPA-2CHT3-CE-ATM does not support differential clock recovery.
•
The maximum number of differential clocks sourced from a 24-Port Channelized T1/E1 ATM CEoP
SPA are 24.
•
The 24-Port Channelized T1/E1 ATM CEoP SPA can recover up to 24 T1 or E1 clocks.
•
Several bundles are sent from the same port. The bundle that is used for carrying the clock of the port
is the bundle that is created for the port. Only pseudowires that include the first DS0 of a port, can carry
differential clocks.
To configure clock recovery on a 24-Port Channelized T1/E1 ATM CEoP SPA, a 2-Port Channelized T3/E3
ATM CEoP SPA, or a 1-Port Channelized OC-3 STM1 ATM CEoP SPA, perform the following procedure:
SUMMARY STEPS
1.
Router(config)#
recovered-clock slot subslot
2.
Router(config-clock)#
clock recovered clock-id
{
adaptive
|
differential
}
cem port cem-group
3.
Router(config-clock)#
clock reference
{
enhanced
|
internal
}
4.
Router(config-clock)#
clock master
5.
Router(config-clock)#
clock slave
DETAILED STEPS
Purpose
Command or Action
Specifies the slot and subslot for the recovered clock.
Router(config)#
recovered-clock slot subslot
Step 1
Specifies the recovered clock number and the clock
recovery type.
Router(config-clock)#
clock recovered clock-id
{
adaptive
|
differential
}
cem port cem-group
Step 2
Specifies the clock reference.
Router(config-clock)#
clock reference
{
enhanced
|
internal
}
Step 3
Configures the clock master.
Router(config-clock)#
clock master
Step 4
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS
XE Everest 16.5
520
OL-14127-17
Configuring the Circuit Emulation over Packet Shared Port Adapter
Configuring Clock Recovery