To Next Page

To Previous Page

GEN7iB

286

GEN series SYNCHRONIZATION METHODS

14.2.4 PTP switch types

WithinthePTPspecication,twotypesofswitchesaredened:

● Boundary clock switches

● Transparent clock switches

Boundary clock

BoundaryclocksaredenedwithinaPTPsystemtobeintegratedinplacewherestan-

dardnetworkswitchesorroutersareused.BoundaryclocksaredenedasPTPclocks

with more than a single PTP port, with each port providing access to a separate PTP

communication path. The boundary clock acts as an interface between separate PTP

domains intercepting and processing all PTP messages and passing all other network

trac.TheBMCalgorithmisusedbytheboundaryclocktoselectthebestclockany

port can see. The chosen port (the one that receives the best clock) is set as a slave

and all other ports of the boundary clock are asserted as masters to their domain (to

forward the clock).

Transparent clock

Transparent clocks have been added to Version 2 of the standard as an improved

method of forming cascaded topologies. Rather than acting as a multi-port ordinary

clock as boundary clocks do, transparent clocks update a newly introduced time-inter-

valeldwithinPTPeventmessages.This64bittime-intervalcorrectioneldallowsfor

switch delay compensation to a potential accuracy of less than a picosecond. There

are two types of transparent clocks, End-to-End and Peer-to-Peer. End-to-End transpar-

entclocksupdatethetimeintervaleldforthedelayassociatedwithindividualpacket

transfers, whereas Peer-to-Peer transparent clocks measure the line delay associated

withtheingresstransmissionpathandincludethisdelayinthecorrectioneldalso.

Peer-to-Peertransparentclockscanallowforfasterrecongurationafternetwork

topology changes.

HBK GEN7iB GEN Series User Manual

Questions and Answers: