Cisco Systems 1000 Series Manual De Usuario

Grand Master--An IEEE1588v2 PTP network needs a grand master to provide a precise time 
source. The most economical way of obtaining the precise time source for the grand master is 
through a Global Positioning System (GPS) because it provides +/- 100 nanosecond (ns) accuracy. 
First, the PTP grand master’s built-in GPS receiver converts the GPS timing information to PTP time 
information, which is typically Coordinated Universal Time (UTC), and then delivers the UTC time 
to all the PTP clients.

PTP client--A PTP client has to be installed on servers, network-monitoring and 
performance-analysis devices, or other devices that want to use the precise timing information 
provided by PTP, and it’s mostly an ordinary clock. The two kinds of PTP clients are pure software 
PTP clients and hardware-assistant PTP clients. 

PTP boundary clock--Any router that is between a PTP master and PTP slave can act as a PTP 
boundary clock router. It has two interfaces, one facing the PTP master and another facing the PTP 
slave. The boundary clock router acts as a slave on the interface facing the PTP master router, and 
acts as a master on the interface facing the PTP slave router. The PTP boundary clock router is 
deployed to minimize timing delay in cases where the distance between PTP master router and the 
PTP slave router is more.

Intermediary nodes between PTP master and slave should be a PTP-enabled or transparent clock node.

 shows the functions of a PTP Enabled device.

Clock synchronization is achieved through a series of messages exchanged between the master clock and 
the slave clock as shown in 

.

PTP Master

M - Master Port
S - Slave Port

PTP TC

PTP Boundary

PTP Slaves

S

S

M

S

M

M

M

S

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8

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