(S)NTP synchronization on SG300 access switches?

[Boudewijn Plomp]

Hi,

In our network two Domain Controllers are configured as the central (S)NTP Servers. For a switch in Layer 3 mode it is quit easy to synchronise with these (S)NTP Servers. But what is actually the best approach for access switches in layer 2 mode, that are connected to the layer 3 switch? The only IP Address they have are part of the management VLAN ID 1 which is not routable. I am actually looking for something like a broadcast without having to put a NTP Server in management vLAN.

Boudewijn

[rocater]

Hello Boudewijn,

You should be able to point across vlans using the layer 3 switch as a gateway for your layer 2 switch. Once you have that set you can us your servers to get the time. This setting is under Administration > Management Interface > IPv4 Interface.

[Boudewijn Plomp]

The layer 2 switches are configured with an IP Addres in the management VLAN ID 1, known as the default VLAN. That VLAN is not routable. Correct me if I am wrong.

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[rocater · Accepted solution]

Is your layer 3 switch the gateway for your vlans? Vlan 1 can be routed, the only restriction to this would be if you do not have any routes for vlan1. If your NTP server and layer 2 switch points their default gateway at your layer 3 switch, the layer 3 switch can route traffic across that way.

It really depends how you have the network setup and what device is handling the routing for you on the local network.

[Boudewijn Plomp]

Problem solved. I use a default gateway on the layer 2 switches. I was surprised that the default VLAN is routable. I thought i read somewhere it was isolated. Anyway, it works. Thanks.

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