Basic System Configuration Guide System Management
Edition: 01 3HE 11010 AAAC TQZZA 225
• 16-port T1/E1 ASAP Adapter card (version 1 is not supported on the
7705 SAR-18)
• 32-port T1/E1 ASAP Adapter card
• 7705 SAR-M (variants with T1/E1 ports)
• 7705 SAR-A (variant with T1/E1 ports)
• T1/E1 ports of the 4-port T1/E1 and RS-232 Combination module when it is
installed in the 7705 SAR-H
• T1/E1 ports on the 7705 SAR-X
ACR is not supported on DS1 or E1 channels that have CAS signaling enabled.
ACR is supported for Cpipe services. In addition, ACR is supported on MEF 8 Epipe
services. The MEF 8 Epipe may be a TDM SAP to Ethernet SAP or a TDM SAP to
spoke SDP. Refer to the 7705 SAR Services Guide, “MEF 8”, for information on MEF
8.
There is no extra equipment cost to implement ACR in a network because this
technique uses the packet arrival rate of a TDM pseudowire within the 7705 SAR to
regenerate a clock signal. Additionally, the nodes in the network that are traversed
between endpoints do not need special ACR capabilities. However, because the
TDM pseudowire is transported over Layer 2 links, the packet flow is susceptible to
PDV.
To achieve the best ACR performance, follow these recommendations:
• use a packet rate between 1000 pps and 4000 pps. Lower packet rates cause
ACR to be more susceptible to PDV in the network.
• limit the number of nodes traversed between the source-end and the ACR-end
of the TDM pseudowire
• enable QoS in the network with the TDM pseudowire enabled for ACR classified
as NC (network control)
• maintain a constant temperature, as much as possible, because temperature
variations will affect the natural frequency on the internal oscillators in the
7705 SAR
• ensure that the network does not contain a timing loop when it is designed
6.4.3.1 ACR States
There are five potential ACR states:
•normal
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