Alcatel-Lucent 7210 SAS M Configuration Guide

System Basics Introduction
Page 236 7210 SAS M, T, X, R6 Basic System Configuration Guide
IEEE 1588v2 can function across a packet network that is not PTP-aware; however, the
performance may be unsatisfactory and unpredictable. PDV across the packet network varies with
the number of hops, link speeds, utilization rates, and the inherent behavior of the routers. By
using routers with boundary clock functionality in the path between the grand master clock and the
slave clock, one long path over many hops is split into multiple shorter segments, allowing better
PDV control and improved slave performance; see Figure . This allows PTP to function as a valid
timing option in more network deployments and allows for better scalability and increased
robustness in certain topologies, such as rings. Boundary clocks can simultaneously function as a
PTP slave of an upstream grand master (ordinary clock) or boundary clock, and as a PTP master of
downstream slaves (ordinary clock) and/or boundary clocks. The time scale recovered in the slave
side of the boundary clock is used by the master side of the boundary clock. This allows time to be
distributed across the boundary clock.
Figure 21: Boundary Clock
Configuration guidelines and restrictions for PTP
• On 7210 SAS-M and 7210 SAS-X, use of PTP and syncE as a reference simultaneously is
not allowed. User can configure either syncE as a reference or PTP as a reference, but not
both together.
• 7210 SAS-T allows use of PTP and syncE as a reference simultaneously, that is, on 7210
SAS-T ref-order can be set to - configure> system> sync-if-timing> ref-order ref1 ref2
ptp.

Alcatel-Lucent 7210 SAS M Specifications

General

Brand	Alcatel-Lucent
Model	7210 SAS M
Category	Switch
Language	English