Losing DHCP leases and System Time on reboot

[romaingtp]

Hello

I have two SG350-10 switches, that I want to set as DHCP servers for a local control network. I followed instructions, and it worked fine, until the server had to reboot. As soon as it was back online I noticed several issues :

• The devices can't reconnect to the nework (no assigned IP)
• I can connect with a computer or an iPad by using a static IP on the same subnet as the switch
• In the "IP binding" tab, every DHCP leases (which I tried to set on Infinite, then 45 days, then 1 hour) are expired
• The "System time", previously synchronized with the computer, is back to default.

I tried on both switches, and had the same results. Could it be a dead CMOS battery ? I can't find any information about it's life expectancy or it's replacement.

Thank you for your time.

[balaji.bandi]

check some suggestion i have made in the previous post - make sure save the config as expected.

the only config you looking DHCP and NTP ? rest all ok - try upgrade to latest firmware if you are already not done so.

https://community.cisco.com/t5/switching/cisco-sg350-28p-vlan-s-not-holding-after-reboot/td-p/4487586

[romaingtp]

If I get it, I need to go in the "copy/save config" after every edit and save the "running config" as a "startup config" ? I thought the "save" button appearing in the top of the screen had this purpose already.

I'll try to update the firmware too, thanks for the reminder.

[liviu.gheorghe]

Hello @romaingtp ,

the problem with the DHCP server running on the SG350 is that the IP address bindings for the PC's on the LAN are kept in RAM. If the switch reboots, all the RAM contents is cleared and IP address bindings are lost. The PC's should use the already assigned IP address or do a IP address release followed by a IP address renew - on Windows the command is ipconfig /release and ipconfig /renew.

If this is a problem for your environment, I would suggest moving your DHCP server on a Windows Server, which maintains the IP address binding in a file and reads them after a reboot, or configure it on a router or switch that runs IOS or IOS XE in which you have the option to write the IP address bindings to a file on the systems flash or tftp server and read the file after a reload thus preserving the same IP bindings. 

The lease time for IP addresses should be set to something like 4-8 hours.

Regarding the system clock of the switch, you should configure it to use a SNTP server. Configure it from Administration -> Time Settings -> System Time and Administration -> Time Settings -> SNTP Unicast

Hope this helps.

[romaingtp]

Hello, and thank you for your answer.

I cannot use a server as you suggest; my goal is to set up a local network for remote control and monitoring data for various sound and video equipments in the theater I work for. A lot of those devices are manageable through IP only, and a long lease was to prevent them to change have their IP reattributed to another device (45 days is the longest the devices would stay offline). I managed to do a similar installation with another switch (not a cisco).

For the issue I encounter, what bothers me is that the IP bindings are not "lost" on reboot. All IP are still bound to MAC adresses, but leases are "expired", even if set to infinite.