C H A P T E R
10-1
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
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10
Synchronous Ethernet Support
Synchronous Ethernet (SyncE) defined by the Telecommunication Standardization Sector (ITU-T)
standards, such as G.8261 and G.8262, leverages the PHY layer of the Ethernet to transmit clock
information to the remote sites.
This chapter covers the following topics:
•
Synchronous Ethernet Overview
•
Synchronization Status Message and Ethernet Synchronization Messaging Channel
•
Restrictions and Usage Guidelines
•
Configuring Synchronous Ethernet
Synchronous Ethernet Overview
SyncE over Ethernet provides a cost-effective alternative to the Synchronous Optical Networking
(SONET) networks. For 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 Routers have a dedicated external interface known as BITs interface to recover
clock from a Synchronization Supply Unit (SSU). ASR 1000 router uses this clock for SyncE. The BITS
interface supports E1(European SSUs) and T1 (American BITS) framing.
Table 10-1
lists the framing modes for a BITS port on a Cisco ASR 1000 Series Router:
Table 10-1
Framing Modes for a BITS Port on a Cisco ASR 1000 Series Router
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
E1
E1 FAS
No
No
Yes
E1
E1 CAS
No
No
Yes
E1
E1 CAS CRC4
No
No
Yes
2048 kHz
2048 kHz
No
No
Yes
