# US 2019/0356403 A1 · Symmetric path/link over lag interface using lldp for time synchronization between two nodes using ptp

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- Number: US 2019/0356403 A1
- Document ID: US20190356403A1
- Status: Published application
- Kind: A1
- Application number: 15/982,901
- Filed: 2018-05-17
- Published: 2019-11-21
- Earliest claimed: 2018-05-17
- Assignees: Juniper Networks, Inc.
- Applicants: Juniper Networks, Inc.
- Inventors: Prabhu Raj V.K.; Kamatchi S. Gopalakrishnan; Ramana M. Reddy
- Web page: https://patentgrep.com/patent/US20190356403A1

## CPC

- H04L 45/245: {Link aggregation, e.g. trunking}
- H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)}
- H04J 3/0673: {using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet}
- H04L 47/24: Traffic characterised by specific attributes, e.g. priority or QoS
- Y02D 30/00: Reducing energy consumption in communication networks
- Y02D 30/50: in wire-line communication networks, e.g. low power modes or reduced link rate
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A network device may assign, to a port of a plurality of ports on the network device, a precision timing protocol (PTP) port priority for PTP communications between the network device and another network device. The network device and the other network device may be communicatively connected via a plurality of links in a link aggregation group (LAG). Each port, of the plurality of ports, may be associated with a respective link, of the plurality of links, in the LAG. The network device may generate a link layer discovery protocol (LLDP) frame that includes information identifying the PTP port priority assigned to the port. The network device may transmit the LLDP frame to the other network device to identify, to the other network device, the PTP port priority.

## Claims

### Claim 1

A network device, comprising:
one or more memories; and
one or more processors to:
assign, to a port of a plurality of ports on the network device, a precision timing protocol (PTP) port priority for PTP communications between the network device and another network device,
wherein the network device and the other network device are communicatively connected via a plurality of links in a link aggregation group (LAG), and
wherein each port, of the plurality of ports, is associated with a respective link, of the plurality of links, in the LAG;
generate a link layer discovery protocol (LLDP) frame,
the LLDP frame including information identifying the PTP port priority, assigned to the port, for the PTP communications between the network device and the other network device; and
transmit the LLDP frame to the other network device to identify, to the other network device, the PTP port priority.

### Claim 2 (depends on 1)

The network device of claim 1, wherein the one or more processors, when transmitting the LLDP frame to the other network device, are to:
transmit the LLDP frame to the other network device via the port and the respective link associated with the port.

### Claim 3 (depends on 1)

The network device of claim 1, wherein the one or more processors, when assigning the PTP port priority to the port, are to:
assign a respective PTP port priority to each port of the plurality of ports on the network device.

### Claim 4 (depends on 3)

The network device of claim 3, wherein the one or more processors, when generating the LLDP frame, are to:
generate a respective LLDP frame for each port of the plurality of ports on the network device.

### Claim 5 (depends on 1)

The network device of claim 1, wherein the one or more processors, when generating the LLDP frame, are to:
include the information identifying the PTP port priority, assigned to the port, in a time-length-value (TLV) field in the LLDP frame.

### Claim 6 (depends on 5)

The network device of claim 5, wherein a type of the TLV field is at least one of a reserved type or a custom type.

### Claim 7 (depends on 1)

The network device of claim 1, wherein the port is a first port, the plurality of ports is a first plurality of ports, the PTP port priority is a first PTP port priority, and the LLDP frame is a first LLDP frame; and
wherein the one or more processors are further to:
assign, to a second port of a second plurality of ports on the network device, a second PTP port priority for PTP communications between the network device and a further network device;
generate a second LLDP frame,
the second LLDP frame including information identifying the second PTP port priority assigned to the second port; and
transmit the second LLDP frame to the further network device.

### Claim 8

A non-transitory computer-readable medium storing instructions, the instructions comprising:
one or more instructions that, when executed by one or more processors, cause the one or more processors to:
determine, for a plurality of ports on a first network device, a precision timing protocol (PTP) port priority order for PTP communications between the first network device and a second network device,
wherein the first network device and the second network device are communicatively connected via a plurality of links in a link aggregation group (LAG), and
wherein each port, of the plurality of ports, is associated with a respective link, of the plurality of links, in the LAG;
assign, based on the PTP port priority order, a respective PTP port priority to each port of the plurality of ports;
for each port of the plurality of ports:
generate a respective link layer discovery protocol (LLDP) frame, the respective LLDP frame, for a port of the plurality of ports, including information identifying the respective PTP port priority assigned to the port; and
transmit the respective LLDP frame to the second network device.

### Claim 9 (depends on 8)

The non-transitory computer-readable medium of claim 8, wherein the PTP port priority order defines an order in which the plurality of ports are to be used for the PTP communications between the first network device and the second network device.

### Claim 10 (depends on 8)

The non-transitory computer-readable medium of claim 8, wherein the one or more instructions, that cause the one or more processors to assign the respective PTP port priority to each port of the plurality of ports, cause the one or more processors to:
assign a first PTP port priority to a first port of the plurality of ports; and
assign a second PTP port priority to a second port of the plurality of ports,
wherein the first PTP port priority is a higher priority relative to the second PTP port priority.

### Claim 11 (depends on 10)

The non-transitory computer-readable medium of claim 10, wherein the one or more instructions, when executed by the one or more processors, further cause the one or more processors to:
perform, based on the first PTP port priority, the PTP communications between the first network device and the second network device using the first port;
detect a fault on the respective link associated with the first port; and
perform, based on the second PTP port priority and based on detecting the fault, the PTP communications between the first network device and the second network device using the second port.

### Claim 12 (depends on 8)

The non-transitory computer-readable medium of claim 8, wherein the one or more instructions, that cause the one or more processors to determine the PTP port priority order, cause the one or more processors to:
determine the PTP port priority order based on at least one of:
a respective bandwidth associated with each link of the plurality of links,
a respective latency associated with each link of the plurality of links, or
a respective port identifier associated with each link of the plurality of links.

### Claim 13 (depends on 8)

The non-transitory computer-readable medium of claim 8, wherein:
the first network device is associated with at least one of a first PTP boundary clock or a first PTP ordinary clock; and
the second network device is associated with at least one of a second PTP boundary clock, a second PTP ordinary clock, a PTP transparent clock, or PTP unaware node.

### Claim 14

A method, comprising:
receiving, at a port of a plurality of ports on a first network device, a link layer discovery protocol (LLDP) frame from a second network device,
wherein the first network device and the second network device are communicatively connected via a plurality of links in a link aggregation group (LAG), and
wherein the port is associated with a link of the plurality of links in the LAG;
identifying, by the first network device, precision timing protocol (PTP) information included in the LLDP frame;
determining, by the first network device and based on the PTP information included in the LLDP frame, a PTP port priority for PTP communications between the first network device and the second network device;
assigning, by the first network device, the PTP port priority to the port; and
performing, by the first network device and based on the PTP port priority assigned to the port, the PTP communications between the first network device and the second network device.

### Claim 15 (depends on 14)

The method of claim 14, wherein the PTP information included in the LLDP frame includes a PTP information type identifier and a PTP priority identifier.

### Claim 16 (depends on 15)

The method of claim 15, wherein determining the PTP port priority comprises:
determining the PTP port priority based on the PTP information type identifier and the PTP priority identifier.

### Claim 17 (depends on 15)

The method of claim 15, wherein the port is a first port and the PTP port priority is a first PTP port priority; and
wherein the PTP priority identifier corresponds to a second PTP port priority assigned to a second port on the second network device.

### Claim 18 (depends on 14)

The method of claim 14, wherein the port is a first port; and
wherein performing the PTP communications between the first network device and the second network device based on the PTP port priority assigned to the first port comprises:
performing the PTP communications between the first network device and the second network device via a second port, of the plurality of ports, on the first network device.

### Claim 19 (depends on 18)

The method of claim 18, wherein the link is a first link; and
wherein the method further comprises:
detecting a fault in a second link, of the plurality of links in the LAG, associated with the second port; and
performing, based on detecting the fault and based on the PTP port priority assigned to the first port, the PTP communications between the first network device and the second network device via the first port.

### Claim 20 (depends on 14)

The method of claim 14, wherein identifying the PTP information included in the LLDP frame comprises:
identifying the PTP information in a time-length-value (TLV) field in the LLDP frame,
wherein a type of the TLV field includes at least one of a reserved type or a custom type.