NTP Sync problem

[enkhbat.n]

Hello Guys,

I hope you guys can help my problem I have faced.

Our connection is structured as Ring and implemented by Cisco devices. We enable trunk VLAN and access VLAN for every connection. One of these connection has enabled NTP sync for their data transmission. If sync failed, data will not transmit. Recently, that sync is not able to work on our network.

During the problem, every transmission was working well except NTP sync. So, we were investigating all connection. Weird thing is that when we sat down VLAN 588 and 602, that NTP sync worked fine (which is working on VLAN 47 and 48), and if we sat it back to up, NTP sync failed again as same.

Please help me.

What should I check first?

When we were investigating the captured packet, we saw some protocol such as VRRP was used. These VLANs don't have any common connection and VLAN, and it happens either access or trunk.

Regards,

Bat

[Panos Kampanakis]

First I would suggest you to check connectivity of the devices in the vlans with their ntp server. If the lose connectivity through the trunked vlans for example they won't be able to sync up.

Secondly, I would look for NTP packet captures towards the server and see if there are drops in the path and if the server sees them and responds.

I hope it guides you to the right direction.

PK

[enkhbat.n]

Thank you for your msg.

I checked and captured all that things, but there is nothing as suspectable. Only thing is these 2 nets enabled VRRP. We guess that things maybe influence to NTP sync. Is that possible? Is there any influence on 2 different VRRP enabled networks?

Regards,