"DHCP Mode" not working on the GS116Ev2 switch (firmware version 18.104.22.168)
DHCP Mode is not working on the GS116Ev2 (ProSafe Plus 16-port gigabit switch). The problem happens on firmware version 22.214.171.124 (latest one for this model at time of writing this post). Downgrading firmware to version 126.96.36.199 does not improve the behavior; we have not downgraded firmware on this switch to v2.0 releases.
As a difference with a comparable model (the GS108Ev3) this one has "DHCP Mode" supposedly disabled by default (more on this later.) I am not sure it is the expected behavior, documentation disagrees with this setting being disabled by default, so I want to note it in case it matters.
This is what we found so far:
- starting on factory defaults: we cannot set "DHCP Mode" field to "Enable" (the "Apply" button reboots the switch but DHCP Mode returns to "Disable").
- We are not really sure it is disabled by default; we have not set up a DHCP server on our network, but the switch needs one minute and a half to boot on factory defaults, so it seems it is looking for a DHCP server; setting "DHCP Mode" to "Enable" (so the "Apply" button changes to blue color), then to "Disable" again, and applying the change seems to disable DHCP mode. After following the "DHCP Mode enable" → "DHCP Mode disable" → "Apply" sequence the switch boots in less than twenty five seconds, something comparable to the six seconds a GS108Ev3 needs to boot when DHCP Mode is disabled. Now DHCP Mode is really disabled.
- We are aware of the relation between DHCP Mode, Broadcast Forwarding and Switch Management Mode on this model. So, no, the broadcast forwarding method or switch management mode do not interfere with DHCP Mode.
Is it a known problem?
Re: "DHCP Mode" not working on the GS116Ev2 switch (firmware version 188.8.131.52)
To make it clear... on a GS116Ev2 with up to date firmware:
- whatever you do to change the "DHCP Mode" field, there is no way to let it stay enabled after rebooting the switch;
- it seems, however, the switch on factory settings acts as a DHCP client (even if the DHCP Mode is disabled); the only way I know to disable the DHCP Mode is following the sequence "DHCP Mode enabled" (to turn the Apply button blue) → "DHCP Mode disabled (again)" → "Apply"; this way it boots in less than thirty seconds instead of ninety seconds.
I can temporarily set up a DHCP server on my network or use tcpdump(8) to identify DHCP requests coming from the switch if it helps debugging this issue; but the time required to boot the switch is a strong indicator DHCP Mode can be enabled or disabled... look however at point (1) — after rebooting the switch "DHCP Mode" field always shows "disabled".
I would say DHCP Mode works under the hood, but "DHCP Mode" always shows "disabled" after rebooting the appliance.