Guidelines For Configuring Ptp Over Ethernet - Juniper ACX1000 Configuration Manual

ACX Series Universal Access Router Configuration Guide
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Guidelines for Configuring PTP over Ethernet

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over Ethernet. In such a scenario, the ACX Series router functions as a boundary clock
with a PTP slave port using IPv4 as the encapsulation mode and master ports using
Ethernet as the encapsulation mode for PTP traffic. For example, consider an ACX Series
router named ACX1 to have two potential slave interfaces, one that is fixed as a slave-only
port using IPv4 on the link toward an MX Series router named MX1, and a dynamic port
that functions as a slave port using PTP over Ethernet on the link toward another ACX
Series router named ACX2. In addition, ACX1 also contains a port that is a master-only
port using PTP over Ethernet and connects to the base station.
Because PTP over Ethernet uses multicast addresses, a slave port can automatically
start receiving the multicast announce messages transmitted by the master ports on a
network and can also start communication with the master node with minimal or no
configuration. Unlike PTP over IPv4 where IP addresses are used to identify the master
and slave ports, with PTP over Ethernet, multicast MAC addresses are used in the
forwarding of PTP traffic. The IEEE 1588 standard defines two types of multicast MAC
addresses 01-80-C2-00-00-0E (link local multicast) and 01-1B-19-00-00-00 (standard
Ethernet multicast) for PTP over Ethernet operations.
Guidelines for Configuring PTP over Ethernet on page 240
Configuring PTP Multicast Master and Slave Ports for Ethernet Encapsulation on
page 274
Configuring PTP Dynamic Ports for Ethernet Encapsulation on page 280
Example: Configuring PTP over Ethernet for Multicast Master, Slave, and Dynamic
Ports on page 281
Keep the following points in mind when you configure PTP over Ethernet for multicast
mode of transmission of PTP traffic:
You can configure a port or a logical interface to be a master clock for PTP over Ethernet
to provide packet-based synchronization to base stations that support time and phase
alignment; this configuration is compliant with Annexure F of the IEEE 1588-2008
specification.
Two multicast MAC addresses are used for PTP over Ethernet: 01-1B-19-00-00-00
and 01-80-C2-00-00-0E. The first address is a more standard Ethernet MAC address
that is expected to be flooded by all types of Ethernet bridges and switches and also
by a large number of base station vendors. A node with this MAC address can be a
node that does not process PTP packets. The second address is a reserved address in
the IEEE 802.1Q standard for Ethernet encapsulation that is required to be filtered and
not forwarded. This MAC address is used to ensure complete end-to-end support of
PTP, instead of transmission of packets through any network element that does not
support PTP. This address is the default address for G.8275.1 (PTP Profile for time or
phase distribution) and a node with this MAC address is a node that supports processing
of PTP packets.
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