Issue with Static IP Adressing

[budest]

Hi guys,

Client has 6 x Windows 10 workstations with a mixture of hardwired and wireless network connections. All run through a Cisco 887VAM to a switch to a wireless access point. Reason for the Cisco is there is an installed telephone network.

I don't know anything about configuring a Cisco and advised the client of same but each workstation requires a static I.P. as they must accept incoming connections from a network scanner. So I assigned static IPs at the workstation end but after a few weeks they are losing network access. When I release the static IP the stations are acquiring a new IP via DHCP and gaining access again. Then it's rinse and repeat, static IP assigned, working for a few weeks then dropping connection again.

I have advised the client that they should go back to the telephony guys and ask that they attend the property and assign fixed IPs to MAC addresses at the router end but I am curious as to why this was/is happening. The static IPs I was assigning were all in the 192.168.X.X range so why would they eventually be refused network access?

Any help or guidance would be appreciated.

 

[Alabalcho]

Configure the DHCP server to assign permanent addresses based on MAC address. This way, all clients will still be configured DHCP way, but will always get same IP address.

 

[budest]

Configure the DHCP server to assign permanent addresses based on MAC address. This way, all clients will still be configured DHCP way, but will always get same IP address.

Thanks for that. As I suspected, the best way to solve it is to assign static IPs to MACs. Thanks for confirming.

 

[hang-the-9]

When you set the computers to static IP, did you then remove those IPs from the DHCP range?

 

[androbourne]

Yes. In DHCP it is called creating reservations. You are best to create a DHCP scope and make reservations for PCs outside of the scope. This can also be done at the firewall level if you do not have a DHCP server.

Example is creating a DHCP scope of 192.168.1.1-192.168.1.254 then exclude 192.168.1.1-192.168.1-100. Save these first 100 for anything that requires state IPs such as servers, printers, workstations etc...