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?

[kolping-mw]

Which will be also a question of money. It has some reasons why we are using the small business versions and except this one they fit very good in our concept as the next problem is to find Gigabit PoE switches with 10G uplinks which are passive...

Cisco Partner doesn't make sense in my experience. Most of them which sell the small business series are not in so deep at technical level.

And without an contract there is NO way to contact Cisco. Tried it yesterday. So for now we are looking for the prices for a contract for one device over which we can open TAC cases for these problems. But it is annoying as this is nothing where we need special support, it is a common global thing.

[pieterh]

I understand your frustration about the different aftre the migration to another switcht.

it is not strange when a device requests "please give me power and reserve a max of 30W for me"
for the switch to fulfill this request and RESERVE 30Watts of power
and not "I will say I'll reserve 30W,  but if someone else needs it I will give it away and give you only what you use now"

In my opinion  a device that does not NEED this 30 Watts,
should be able to be configured not to demand this reservation from the switch
if that is possible, is a question that should be answered by Lancom

[kolping-mw]

Nothing to say against that. But in ONE company it should stay the same or at least it should be consequent over all series...

I am not giving up that this is possible to be implemented by a firmware upgrade. So I will go both pathes and will contact Cisco AND Lancom because that what you describe is the next point which should be changed by Lancom.

[kolping-mw]

Current situation:

• no answer from Lancom as they are overloaded (for month...)
• bought a service contract for one device and opened a case at Cisco (695392396)

[kolping-mw]

"Final" message to this with TAC:

[quote]

I am not sure what is your observation over SG300 switches, but in our lab tests we see that SG300 switch does not negotiate power over CDP/LLDP. In that scenario the switch does not allocate power and PDs get power negotiated only via IEEE methods.

On the other hand CBS switch negotiates power with PD over CDP/LLDP and this makes the CBS switch to allocate power from the power budget not letting it be actually used. You can accomplish same effect using the interface command “power inline negotiation none”.

[/quote]

So, everybody who doesn't want to use the reservation function has to deactivate the negotiation via "power inline negotiation none"