wpns
Posts: 85
Joined: Sat Sep 01, 2012 2:50 pm

PoE HAT, no ethernet on Cisco SG300, but works on SG500

Tue Sep 11, 2018 7:21 pm

Not sure if this is the same issue as "eth0 not working", but I've just discovered that my Pi3B+ with PoE HAT powers up but doesn't bring up the ethernet port when connected to a Cisco SG300-28PP, but works fine on an SG500-28P

NOTE: This only applies to NOOBS Lite V2.8, once I've installed the Raspian desktop it the Ethernet works on the SG300 as well.

wpns
Posts: 85
Joined: Sat Sep 01, 2012 2:50 pm

Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Tue Sep 11, 2018 10:24 pm

Addenda: Its stranger than that. SG500 takes a while but comes up at gigabit.
SG300 works sometimes and not others, but comes right up when forced to 100M.

Some esoteric handshaking or timing thing here...

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Wed Sep 12, 2018 6:12 am

Have you checked/replaced the ethernet cable? Gigabit requires all 4 pairs to be working. 100M only requires two. The ethernet chip on the Pi does not downgrade to 100M if it finds it is missing pairs.
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wpns
Posts: 85
Joined: Sat Sep 01, 2012 2:50 pm

Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Wed Sep 12, 2018 7:53 am

Oh yeah, several ports, several cables, going to try a couple of other switches tomorrow.

wpns
Posts: 85
Joined: Sat Sep 01, 2012 2:50 pm

Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Sat Sep 15, 2018 12:14 pm

Same problem on an SG300-10PP, the link doesn't come up till you set it to 100M, then it works.

Stuart-JW
Posts: 14
Joined: Sat Aug 18, 2018 2:18 pm

Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Sat Sep 15, 2018 2:34 pm

I have the cisco sg300-10mpp.

auto negotiation at gigabit worked ok for my poe hat.
i only had to drop to 100 mb when i use the poe splitters which are only rated at 100mb.
maybe there is some difference between pp and mpp models ?

wpns
Posts: 85
Joined: Sat Sep 01, 2012 2:50 pm

Re: PoE HAT, no ethernet on Cisco SG300, but works on SG500

Sat Sep 15, 2018 3:04 pm

Also, FWIW:

https://fe-pi.com/products/fe-pi-poe-v1

works fine on both SG500 and SG300 switches. Doesnt' have the fan, and doesn't come with standoffs, and makes the assembly higher, so it doesn't fit in the standard case without removing the top, but a little less money and it actually works. 8*)

No idea if they have the same USB issues, but can't imagine they do...

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