# PTP Struggles and Solutions after Migrating to Rev7 Sensors

**URL:** <https://community.ouster.com/t/ptp-struggles-and-solutions-after-migrating-to-rev7-sensors/429>\
**Category:** Hardware\
**Tags:** ptp, time-synchronization\
**Created:** [December 10, 2025, 10:07pm UTC](https://community.ouster.com/t/ptp-struggles-and-solutions-after-migrating-to-rev7-sensors/429 "2025-12-10T22:07:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![schmaelle](https://avatars.discourse-cdn.com/v4/letter/s/f4b2a3/32.png) [@schmaelle](https://community.ouster.com/u/schmaelle)\
**Post date:** [December 10, 2025, 10:07pm UTC](https://community.ouster.com/t/ptp-struggles-and-solutions-after-migrating-to-rev7-sensors/429/1 "2025-12-10T22:07:08Z")

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I post this only for others who might stumble upon similar problems.  
With the great help of the Ouster Support we where able to figure out all issues during the migration process.

But as it was far from _Plug and Play_ as I had hoped for - just unplug old OSx , plug in new OSx and go - I report here our findings.

Thanks again to the Ouster support!

## HW Setup:

- Novatel PwrPak7 as GM Clock → ETH `enp5s0`
- `CLOCK_REALTIME` is synched via `chrony SHM` to this port
- `phc2sys` syncs all other ETH ports to `CLOCK_REALTIME`
- at `enp3s0s0` a automotive grade switch (hw ptp enabled) is connected
- three Ouster LiDAR are connected to this switch (OS0, OS1, OS2)

* * *

## PTP Setup with Rev5+Rev6 Sensors

- Ubuntu 20.04
- `linuxptp` v3.1.1 installed via `apt`
- OS0, OS1, OS2 with FW 2.5.3
- ptp\_profile `default-relaxed`
- IP of Sensors as `static_ip`: `169.254.xxx.xxx`

#### Results

All sensors would converge to `port_state==SLAVE` stable. `master_offset` was within spec \<250.000ns

* * *

## PTP Setup with Rev7 Sensors

We then updated to newer Rev7 sensors to gain from the better performance.

### Setup Number 1:

- Ubuntu 20.04
- `linuxptp` v3.1.1 installed via `apt`
- OS0, OS1 with FW 3.1.0
- OS2 with FW 2.5.3
- ptp\_profile `default-relaxed`
- IP of Sensors as `static_ip`: `169.254.xxx.xxx`

#### Issues

Only the OS2 would sync into `SLAVE`. OS0 and OS1 would stay `UNCALIBRATED`

#### Solution

With FW 3.1.x it is no longer ok to set the `static_ip` to the `link_local` range - `169.254.xxx.xxx` although data etc came through, PTP did not like it.

So I reconfigured the IP into `192.168.xxx.xxx` range and it worked.

### Setup Number 2:

- Ubuntu 24.04
- `linuxptp` v4.0 installed via `apt`
- OS0, OS1 with FW 3.1.0
- OS2 with FW 2.5.3
- ptp\_profile `default-relaxed`
- IP of Sensors as `static_ip`: `192.168.xxx.xxx`

Updated host system as I continue working with ROS2 now.

#### Issues

- All three Ousters would report `port_state==SLAVE`. But only OS0 and OS1 are within spec `master_offset` \< 1000ns (FW3.1)

- OS2 `master_offset` was \> 300.000.000ns so 300ms and more.

- Also OS2 would not accept `phase_lock` and reported this Warning:

#### Solution

Motivated from [Issue 99](https://community.ouster.com/t/ptp-stuck-in-uncalibrated/99) I uninstalled `linuxptp` and build it from source with version `3.1.1`

Which did in fact solve the issue.  
So unfortunately it is not possible to use the Ubuntu 24.04 default `linuxptp` package but one has to build the old version. At least for FW 2.5.3. FW 3.1.0 is fine with

With this:

- OS0 + OS1 have a `master_offset` \< 1000ns
- OS2 has a `master_offset` \< 250.000ns

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**Author:** ![yggdrasil](https://yyz2.discourse-cdn.com/flex004/user_avatar/community.ouster.com/yggdrasil/32/44_2.png) [@yggdrasil](https://community.ouster.com/u/yggdrasil)\
**Post date:** [December 15, 2025, 7:03pm UTC](https://community.ouster.com/t/ptp-struggles-and-solutions-after-migrating-to-rev7-sensors/429/2 "2025-12-15T19:03:23Z")

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Great post, thank you! The complexity you experienced is the result of REV7 OS2’s still running on a firmware 2.X while all other REV7 sensors transitioned to firmware 3.X.