Accessing NTP Server from another Subnet

[Tom101]

Hello,

Still quite new to networking. This question has been bothering me for a while. 

How do i access a NTP server that is on another subnet? 

I have attached a screenshot of a basic configuration. SW1 and SW2 can access the NTP clock, but SW3 cannot since it is on a different subnet. How would I set it up so SW3 can access the NTP clock from the NTP server on network 192.168.1.0/24. No routes or VLANs have been set up. 

[Georg Pauwen]

Hello,

the short answer is: SW3 needs IP connectivity to the NTP server, 192.168.1.3. Without that, it cannot get time from that server.

[Tom101]

Thanks Georg. How can that be achieved? I understand that on L3 devices you can use IP Routes to connect different networks together, but how can this be setup with my current topology? 

I also understand you can use ip helper addresses for DHCP. Can something be done similar here? 

[Georg Pauwen · Accepted solution]

Hello,

you need to make SW2 a layer 3 switch. Check the revised file I attached.

[Tom101]

Thank you, that was really helpful. I was able to break down your configuration and learn from it. 

[balaji.bandi]

how is your switch config between SW2 and SW3 ? is this Layer 2 or Layer 3 ?

If 2 different subnets, you need to have some routing place to reach from network to network.

or extendd 192.168.1.X VLAN to SW3 so it can get NTP Information NTP Server.

[Tom101]

Ok, so two L3 switches / routers would be a more suitable choice? 

[balaji.bandi]

how do we bridge 2 Layer 2 networks, you need some router right?

[Leo Laohoo]

The core switch synchronizes with the NTP server. 
The PCs have DHCP Option 42 enabled and point to the core switch.  
No ACLs needed.  

[alexcjuz]

I've been changed your layer 3 switch's config, and add some default-gateway in other devices.

you can see in file.