Cisco ASR1006 - ASR 1006 Modular Expansion Base User Manual

Network Synchronization Support
Network Synchronization Overview
2
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
Network Synchronization Overview
The following goals must be taken into account while designing the synchronization plan for a network:
• Synchronize the greatest number of network elements to the smallest number of independent clock
sources. Ideally, all network elements are synchronized to a single clock source.
• Use clock sources of the highest quality (in terms of stability and long-term accuracy).
• To ensure resiliency of the synchronization, plan for possible failure of the clock sources, network
elements, and network trunks.
Synchronous Ethernet (SyncE) defined by the Telecommunication Standardization Sector (ITU-T)
stand
ards, such as G.8261 and G.8262, leverages the PHY layer of the Ethernet to transmit clock
information to the remote sites.
SyncE provides a cost-effective alternative to the Synchronous Optical Networking (SONET) networks.
F
or SyncE to work, each network element along the synchronization path must support SyncE. To
implement SyncE, the bit clock of the Ethernet is aligned to a reliable clock that is traceable to the
Primary Reference Clock (PRC).
Cisco ASR 1000 Series Aggregation Services Routers ha
ve a dedicated external interface known as BITs
interface to recover clocking information from a Synchronization Supply Unit (SSU). The router uses
this clock for SyncE. The BITS interface supports E1(European SSUs) and T1 (American BITS)
framing.
Table 1 li
sts the framing modes for a BITS port on the Cisco ASR 1002-X Router.
Table 2 li
sts the framing modes for a BITS port on the other Cisco ASR 1000 Series Aggregation
Services Routers.
Ta b l e 1 Framing Modes for a BITS Port on the Cisco ASR 1002-X Router
BITS or SSU Port Support
Matrix
Framing Modes
Supported
SSM or QL
Support Tx Port Rx Port
T1 T1 ESF Yes Ye s Ye s
T1 T1 SF Yes Yes Ye s
T1 T1 D4 Yes Yes Ye s
E1 E1 CRC4 Yes Ye s Yes
E1 E1 FAS Ye s Yes Ye s
E1 E1 CAS Yes Yes Yes
E1 E1 CAS CRC4 Yes Yes Ye s
2048 kHz 2048 kHz Yes Yes Yes
Ta b l e 2 Framing Modes for a BITS Port on the Other Cisco ASR 1000 Series Aggregation
Services Routers
BITS or SSU Port Support
Matrix
Framing Modes
Supported
SSM or QL
Support Tx Port Rx Port
T1 T1 ESF No No Yes
T1 T1 SF No No Yes
E1 E1 CRC4 No No Yes

Cisco ASR1006 - ASR 1006 Modular Expansion Base Specifications

General

Brand	Cisco
Model	ASR1006 - ASR 1006 Modular Expansion Base
Category	Network Router
Language	English