10 Technical Appendix
10.5.3 PTPv2 IEEE 1588-2008 Configuration Guide
Setting up all devices in a PTP synchronization infrastructure is one of the most important parts in a network
time synchronization project. The settings of the involved Grandmaster clocks as the source of time and the
end devices (“Slaves”) have to match in order to allow them to synchronize and avoid problems later, when
the PTP infrastructure is deployed to production environments. In addition to that, the use of PTP aware
network infrastructure components, namely network switches, introduces another set of parameters that have to
be harmonized with the masters and slaves in a PTP setup.
It is therefore very important to start with making decisions how the to-be-installed PTP synchronization
solution should operate, e.g. should the communication between the devices be based on multicast or unicast
network traffic or how often should the masters send SYNC messages to the slaves.
This chapter lists the most important options and their implications on a synchronization environment in general.
A detailed explanation of the configuration settings within the Meinberg Device Manager configuration menu
can be found later within this documentation.
10.5.3.1 General Options
The following general mode options have to be decided before deploying the infrastructure:
1)
Layer 2 (Ethernet) or Layer 3 (UDP/IPv4) connections
2)
Multicast or Unicast
3)
Two-Step or One-Step Operation
4)
End-to-End or Peer-to-Peer Delay Mechanism
The above options need to be defined for the whole setup, if devices do not stick to the same settings, they
will not be able to establish a working synchronization link.
10.5.3.2 Network Layer 2 or Layer 3
PTP/IEEE 1588-2008 offers a number of so-called mappings on different network communication layers. For
Meinberg products you can choose between running PTP over IEEE 802.3 Ethernet connections (network Layer
2) or UDP/IPv4 connections (Layer 3).
Layer 3 is the recommended mode, because it works in most environments. For Layer 2 mode the network
needs to be able to provide Ethernet connections between master and slave devices, which is often not the case
when your network is divided into different network segments and you have no layer 2 routing capabilities in
your network infrastructure.
The only benefit of using Layer 2 mode would be a reduced traffic load, because the transmitted network
frames do not need to include the IP and UDP header, saving 28 bytes per PTP packet/frame. Due to the fact
that PTP is a low traffic protocol (when compared to other protocols), the reduced bandwidth consumption only
plays a role when low-bandwidth network links (e.g. 2Mbit/s) have to be used or in pay-per-traffic scenarios,
for example over leased-line connections.
microSync
Date: 22nd June 2020
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