openwrt ONE: not getting enough PoE power

[Sebastian Moeller]

Hi Michael,

my oldish zyxel PoE switch allows to limit the maximum current per port, maybe the Cisco in question does as well and is set for a borderline low value?

Regards
        Sebastian

On 15 March 2025 04:54:15 CET, Michael Richardson <mcr at sandelman.ca> wrote:
>
>I brought an OpenWRT One to IETF122 Hackathon.
>
>I plugged the 2.5Gb/s port into the IETF hackathon network, and the switch
>apparently has PoE (which I didn't care about).  I hooked up the rest of the cables,
>including the USB power, but didn't turn it on yet.  I was surprised when I
>opened the console that the system was running.... kinda.
>
>With the cable in the PoE port, the device was in a reboot cycle.  Getting to
>just before the console shell starts, and then restarting.  I can post a log
>if that's useful to someone.
>I guess because there wasn't enough amperage on the PoE port.  I unpluged,
>turned on the USB adapter and things were fine... so I reconnected the PoE cable, and
>the system crashed... back to reboot cycle!  Oh.  That's bad.
>
>I "solved" the problem by inserting a my non-PoE switch in between.
>I could have also swapped ports, it now occured to me.
>
>I'm just mentioning this for the benefit for someone searching!
>
>I suppose this is a hardware problem, and probably not solveable.
>Maybe I could cut a trace, or maybe there is a zero-ohm resister I could
>unsolder to disable PoE.
>
>Maybe fixable in Two: prefer USB power if it's present.
>But of course, when I started, it wasn't present, as I wanted the system to
>be off until I was ready: I wanted to finish getting serial console alive
>before I powered on.
>
>The switch in question:
>
>LLDP neighbors:
>-------------------------------------------------------------------------------
>Interface:    enxd43a650cda24, via: LLDP, RID: 2, Time: 0 day, 00:25:46
>  Chassis:
>    ChassisID:    mac cc:98:91:86:53:80
>    SysName:      sw-128.meeting.ietf.org
>    SysDescr:     Cisco IOS Software, C3560CX Software (C3560CX-UNIVERSALK9-M), Version 15.2(7)E11, RELEASE SOFTWARE (fc3)
>                  Technical Support: http://www.cisco.com/techsupport
>                  Copyright (c) 1986-2024 by Cisco Systems, Inc.
>                  Compiled Fri 23-Aug-24 13:34 by mcpre
>
>--
>]               Never tell me the odds!                 | ipv6 mesh networks [
>]   Michael Richardson, Sandelman Software Works        | network architect  [
>]     mcr at sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [
>

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