PTP-Precision Time Protocol configuration example

最为我们熟悉的时间同步协议是NTP,配置起来相对简单,并不复杂;但是NTP实现的毫秒级的时间同步,在普通的网络中只是用来实现网络时间的同步管理。在5G网络中需要一种更为精确的时间同步协议,所以这个文章记录下微妙级的时间同步协议-PTP配置案例。

网络元素

  • Grandmaster (GM) :时间源设备, 所为其他网络设备提供计时,并且不将其本地时钟与其他网络设备同步。
  • T-BC(Boundary Clock):边界时钟, 将其本地时钟与T-GM或上游T-BC时钟同步,并向下游T-BC或T-TSC时钟提供时序信息。
  • T-TSC: time slave clock, 从时钟将其本地时钟与另一个PTP时钟同步,但不向任何其他网络设备提供PTP同步。

设备端口状态

INITPort is not ready to participate in PTP.
LISTENINGFirst state when a port becomes ready to participate in PTP: In this state, the port listens to PTP masters for a (configurable) period of time.
PRE-MASTERPort is ready to enter the MASTER state.
MASTERPort provides timestamps for any Slave or boundary clocks that are listening.
UNCALIBRATEDPort receives timestamps from a Master clock but, the router’s clock is not yet synchronized to the Master.
SLAVEPort receives timestamps from a Master clock and the router’s clock is synchronized to the Master.
PASSIVEPort is aware of a better clock than the one it would advertise if it was in MASTER state and is not a Slave clock to that Master clock.

NCS55 G82751 配置案例

T-GM
RP/0/RP0/CPU0:PE2-NCS55A2-A#show run ptp
Sat Aug 22 16:11:00.559 UTC
ptp
 clock
  domain 24
  profile g.8275.1 clock-type T-GM
  identity mac-address 0100.4817.6033
  clock-class 6
 !
 profile g82751_any
  multicast
  transport ethernet
  sync frequency 16
  announce frequency 8
  delay-request frequency 16
 !
 log
  servo events
  best-master-clock changes
 !
!
RP/0/RP0/CPU0:PE2-NCS55A2-A#
RP/0/RP0/CPU0:PE2-NCS55A2-A#
RP/0/RP0/CPU0:PE2-NCS55A2-A#show run frequency synchronization 
Sat Aug 22 16:11:09.727 UTC
frequency synchronization
 quality itu-t option 1
 log selection changes
!
RP/0/RP0/CPU0:PE2-NCS55A2-A#show ptp interfaces brief 
Sat Aug 22 16:12:44.308 UTC
Intf              Port         Port                  Line
Name              Number       State        Encap    State         Mechanism
--------------------------------------------------------------------------------
Te0/0/0/8         1            Master       Ethernet up            1-step DRRM
RP/0/RP0/CPU0:PE2-NCS55A2-A#
RP/0/RP0/CPU0:PE2-NCS55A2-A#
RP/0/RP0/CPU0:PE2-NCS55A2-A#show run int tenGigE 0/0/0/8
Sat Aug 22 16:12:50.416 UTC
interface TenGigE0/0/0/8
 ptp
  profile g82751_any
 !
 ipv4 address 10.99.1.2 255.255.255.252
 frequency synchronization
  wait-to-restore 0
  quality transmit exact itu-t option 1 PRC
 !
!
T-BC
RP/0/RP0/CPU0:NCS5516-B#show run ptp 
Sat Aug 22 16:37:52.667 UTC
ptp
 clock
  domain 24
  profile g.8275.1 clock-type T-BC
  priority2 100
  clock-class 165
 !
 profile g82751_any
  multicast
  transport ethernet
  sync frequency 16
  announce frequency 8
  delay-request frequency 16
 !
 time-of-day priority 99
 physical-layer-frequency
 log
  servo events
  best-master-clock changes
 !
!

RP/0/RP0/CPU0:NCS5516-B#show run frequency synchronization 
Sat Aug 22 16:38:06.764 UTC
frequency synchronization
 quality itu-t option 1
 log selection changes
!
RP/0/RP0/CPU0:NCS5516-B#show run int tenGigE 0/1/0/0       
Sat Aug 22 16:38:57.615 UTC
interface TenGigE0/1/0/0
 ptp
  profile g82751_any
  port state slave-only
 !
 ipv4 address 10.99.1.1 255.255.255.252
 frequency synchronization
  selection input
  priority 10
  wait-to-restore 0
 !
!

RP/0/RP0/CPU0:NCS5516-B#show ptp interfaces brief          
Sat Aug 22 16:39:01.662 UTC
Intf              Port         Port                  Line
Name              Number       State        Encap    State         Mechanism
--------------------------------------------------------------------------------
Te0/1/0/0         1            Slave        Ethernet up            1-step DRRM
Te0/1/0/1         2            Master       Ethernet up            1-step DRRM
Hu0/0/0/34        4            Master       Ethernet up            1-step DRRM
Hu0/0/0/35        3            Master       Ethernet up            1-step DRRM
           

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