Edge-Core ECS4660-28F, Руководство по управлению, Страница: 599 / 2020

C
HAPTER
14
| Basic Administration Protocols
PTP Configuration
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◆
Delay Mechanism – Sets the delay measurement method for a
boundary clock to one of the following options:
■
End-to-End – This method measures the residence time required
for PTP event messages to cross from the input port to the output
port, and adjusts the time stamp to compensate for this delay. The
value of the correction update and checksums are specific to each
output port and message since the residence time are not
necessarily the same for all paths through the switch or for
successive messages crossing the same path.
■
Peer-to-Peer – This method measures the delay required for PTP
event messages to cross the link from the peer port on the
upstream device to the input port on the switch, as well as the
residence time required for PTP event messages to cross from the
input port to the output port, and adjusts the time stamp to
compensate for both of these delay times.
◆ Transport – Sets the message transport method to one of the
following options:
■
Ethernet – PTP messages are transmitted using Ethernet format.
When using Ethernet as the transport mechanism, PTP messages
use Ethernet formatted packets with the 88F7 Ethertype. PTP
messages use MAC addresses as specified below.
■
IPv4 UDP – PTP messages are transmitted using UDP over IPv4.
When using UDP over IPv4 as a transport mechanism, the following
UDP destination ports are reserved values assigned to PTP.
When using UDP over IPv4 as a transport mechanism, PTP
messages use the multicast addresses as specified below.
Table 40: Ethernet Multicast MAC Addresses
Message Types Address (hex)
All except peer delay mechanism messages 01-1B-19-00-00-00
Peer delay mechanism messages 01-80-C2-00-00-0E
Table 41: UDP/IPv4 Destination Port Numbers
Message Types UDP Port Number
Event message 319
Multicast general message 320
Unicast general message addressed to a clock 320
Table 42: UDP/IPv4 Multicast Addresses
Message Types Address
All except peer delay mechanism messages 224.0.1.129
Peer delay mechanism messages 224.0.0.107