SG350-28P / NTP config

[Mr. S. (archive)]

Dear all,

kindly allow support for a switch newbie like me:

A. HARDWARE

. German type router [Fritzbox 7590 with OS 7.25] and NTP server functionality enabled.

. Switch SG350-28P 28-Port Gigabit PoE Managed Switch and firmware 2.5.7.85 updated

. both in same LAN

B. CONFIGURATION

. I have the router set to obtain time stamp from a European NTP pool and this appears to work fine

. I now want to set my LAN to obtain this router time by NTP. Works fine e. g. for my server. Time deviation there between source (router) and client (server) is at most 10-20 milliseconds

. See screenshots for switch config

C. QUESTION

. Interestingly, the switch does pick up time from router but deviation is typically 1000-1500 milliseconds
(> 1 s). This delta does not appear to converge within a week of operation

Kindly support with your experience and give me a hint on what might be wrong or where I set the wrong buttons. Since I am new to Cisco hardware, please guide me trough as simple as possible (preferably via GUI and not console)

Thank you very much for any reply and support!

[Mr. S. (archive)]

Dear all,

kindly allow support for a switch newbie like me:

A. HARDWARE

. German type router [Fritzbox 7590 with OS 7.25] and NTP server functionality enabled.

. Switch SG350-28P 28-Port Gigabit PoE Managed Switch and firmware 2.5.7.85 updated

. both in same LAN

B. CONFIGURATION

. I have the router set to obtain time stamp from a European NTP pool and this appears to work fine

. I now want to set my LAN to obtain this router time by NTP. Works fine e. g. for my server. Time deviation there between source (router) and client (server) is at most 10-20 milliseconds

. See screenshots for switch config

C. QUESTION

. Interestingly, the switch does pick up time from router but deviation is typically 1000-1500 milliseconds
(> 1 s). This delta does not appear to converge within a week of operation

Kindly support with your experience and give me a hint on what might be wrong or where I set the wrong buttons. Since I am new to Cisco hardware, please guide me trough as simple as possible (preferably via GUI and not console)

Thank you very much for any reply and support!

[Martin Aleksandrov]

Hello Mr. S,

What type of SNTP mode did you set up on the switch - Client Broadcast Reception (passive mode) or Client Broadcast Transmission  (active mode)? If in active mode is it SNTP Anycast Client Mode or Unicast SNTP Server Mode?  (referring the AG on section "SNTP Modes" https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/350xg/admin_guide/AG_Tesla_350_550.pdf )

Kindly try to enable all of them and see if that deviation occurs again. I would also advise using the European NTP Pool directly on the SG350 switch.

Regards,

Martin

[Mr. S. (archive)]

Dear Martin,

thanks for your ideas. They are now implemented. I will let the system run without any additional changes until April 10/11 to review any changes and post any resuilts next week.

Best regards

Steffen

[Mr. S. (archive)]

Dear Martin,

until now, there is no change in behavior. All SNTP modes activated and IP address used. I am still at an offset of ~1200 milliseconds. It makes no difference to previous configuration, see screenshot.

For comparision with another swich, I have tried my "old" SG 300, here offset is around 60-100 milliseconds. Sounds far more reasonable.

Please dig further into issue. Is there maybe something wrong with firmware or even a hardware defect? The SG350 is brand new (approx. 14 days now).

Thanks for you support,

Steffen

[Mr. S. (archive)]

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