[c-nsp] Default CoS

[Victor Sudakov]

Saku Ytti wrote:

[dd]

> 
> It's not very good idea to implement QoS without some idea of your goals.
> At very least you should decide how many classes you need to discriminate
> your traffic into (the fewer you can live with, the better, if you're not
> running QoS now, 2 might be prudent)

My present goal with QoS is simple enough. In the radio relay
equipment we use, the Ethernet bridge can have 4 queues based on CoS
bits. So I don't need more than 4 classes.

I must classify frames so that VLANs with high priority traffic (e.g.
SCADA) never get congested by low priority VLANs for business
applications.  The radio bridge is configured to trust the CoS bits on
input.

> 
> Especially in small Catalysts just turning MLS QoS on pretty much
> invariably makes your life worse than what it was.

Sounds pretty scary. If I could only mark outgoing frames without
actually turning MLS QoS on, that would be fine with me. Is that
possible?

The bottleneck will always be in the radio relay system, not in the
Catalysts themselves, I suppose, just because the bandwidth of the
radio relay is just several STM-1s, nowhere near 1 Gbit/s of
Catalysts' interfaces.

Thanks for the links to documentation.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru