Change of behavior in PoE budget from SG3xx to CBS350

[kolping-mw]

Hello,

we have the problem that we switched from SG300-10MPP to CBS350-8P-2G. So far so nice but the PoE power budget is now calculated in real time and is blocked.

Before we could power our access points easily because the real power amount was counted and therefore much was left.

Real example from today:

- 60W PoE Budget

- 4 Lancom Access 

- Real power consumption all together is around 30W

- Lancom devices reserve up to 25W per device

- If I limit via port to 15W the Lancom devices come up but via LLDP they negotiate out only 12-13W. Seems to be good... but only at first glance

- If Lancom clients have less power than 17W negotiated via LLDP they disable the second Wifi module... although they don't need that much power

What I tried:

- Limit port to 15W -> working but limited wifi power on Lancom

- Disabling "power via mdi" in LLDP messages -> same effect like limiting the port

Someone has another idea to get 4 access points online on these devices?

[pieterh]

is there an extra feature like an USB-port or an LAN-AUX port  on these Lancom device ? (i.e. LAN-out + PoE for a camera or such)
can you disable this feature so the requested power budget is less than 25Watt ?

[kolping-mw]

Good idea. I could ask Lancom if there is a dynamic adaption if you deactivate some features on the devices. BTW: 25W is the maximum I have seen via LLDP. They come out with 17W without deactivating features. This means 20W on the port of the switch (there is some tolerance between this value and the negotiated one based on the 20W). I need 15W on the switch, this means 12-13W for the access point via LLDP as seen on console.

[pieterh · Accepted solution]

btw,   there is another model  CBS350 that has 120W budget,

CBS350-8FP-2G		120W			8
CBS350-8FP-E-2G		120W			8

Cisco Business 350 Series Managed Switches Data Sheet - Cisco

if no other solution works, maybe you can ask your vendor for a swap?

[kolping-mw]

Yep I knew this one but wanted to try if we get a workaround without swapping. At last I changed the model as there was no way to get around the budget. Whether at Cisco nor at Lancom. So thanks for the answer and can be closed like your proposal.