The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a network. Clock synchronization is
achieved by these three elements: Frequency, Phase and Time. Every node in a network must be synchronized with every other
node for these three elements..
PTP allows for separate profiles to be defined for it to be adaptable in different scenarios. A profile is a specific selection
of PTP configuration options, which are selected to meet the requirements of a particular application.
Based on the synchronization requirements of telecommunication networks, ITU-T defines standard profiles based on PTPv2. Some
profiles defined by ITU-T for telecom industry are:
-
ITU-T G.8265.1: Precision time protocol telecom profile for frequency synchronization.
-
ITU-T G.8275.1: Precision time protocol telecom profile for phase/time synchronization with full timing support from the network.
-
ITU-T G.8275.2: Precision time protocol telecom profile for phase/time synchronization with partial timing support from the
network.
This chapter explains how a PTP Boundary Clock which works with multiple PTP profiles, can be configured on the Cisco router.
In a typical PTP network deployment all the participating network elements run on the same PTP profile (1588 / ITU-T G.8275.1
/ ITU-T G.8275.2). However, due to differences in capabilities or functional requirements, some network elements might require
a PTP translation from one profile to another. The PTP multiprofile feature caters to this requirement.
PTP Multiprofile support is achieved in a PTP boundary clock by translating one PTP profile at a
PTP subordinate port to another PTP profile at a PTP primary port.
To translate PTP properties from one profile to other, a special type of "inter-op" clock-port is introduced. This special
clock-port is configured with the required profile and domain information.
With PTP Multiprofile support, the Boundary Clock can run its subordinate port in one profile or
domain and provide the PTP clock to a downstream node in a different profile or domain
by using the new "inter-op" port.
PTP Multiprofile is configured on the Cisco router with the following command:
clock-port port-name <inter-op-port> domain <0-127> inter-op-profile {1588 |g8275.1 |g8275.2}
transport {ipv4/ethernet}
{multicast |unicast} interface interface-type interface-number.
The following diagram which depicts how PTP Multiprofile works on a Cisco router: