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Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
OL-16506-17
Chapter 11 Network Synchronization Support
Prerequisites for Network Synchronization Support
Prerequisites for Network Synchronization Support
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 the network elements should be 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 synchronization, plan for possible failure of the clock sources, network
elements, and network trunks.
Network Synchronization Overview
Synchronous Ethernet (SyncE), which is 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 remote sites.
SyncE 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).
Features Supported on ASR 1000 Platforms
Note Network-Clocking feature is not supported with SFP-GE-T on any of the ASR1000 platforms.
Cisco ASR 1000 Series Aggregation Services Routers have a dedicated external interface known as BITS
interface to recover clocking information from a Synchronization Supply Unit (SSU). They use this
clock for SyncE. The BITS interface supports E1 (European SSUs) and T1 (American BITS) framing.
Platform Support Features Supported Features Not Supported
ASR 1001-X Synchronous Ethernet
Feature is supported with
Built-in Gigabit and
10-Gigabit Ethernet Ports
NetClk Feature
ASR1002-X Synchronous Ethernet
Feature is supported with
Built-in Gigabit Ethernet
Ports.
NetClk Feature
ASR1001 — NetClk and Network Synchronization
Feature
ASR 1002, ASR 1004,
ASR 1006 and ASR 1013
NetClk is supported on all
ASR1000 family routers
apart from ASR1001,
ASR1002-X, and ASR
1001-X.
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