I'm still a little new to QoS overall, but the NX-OS 9500s do things different than what I'm used to.
Looking at implementing a pair of 9504s in a new datacenter. Will be using NX-OS 6.1(2)I3(2).
These things are kinda new, so I've been going through the 9000 Series NX-OS QoS configuration guide.
Question I have is around shaping for QoS in the 9500s.
There is a bandwidth percent command, and that one makes sense. It reserves a percentage of the available bandwidth for a particular queue.
Question is, since this is done in hardware, is it always only allocating that specific amount of bandwidth? For example, if a 1Gbps link isn't congested but a class is assigned 10% of the bandwidth, does it only get 10% or can it use more if no congestion exists?
The other question I'm having is the 'shape' command.
'shape min value {bps | gbps | kbps | mbps | pps} max value {bps | gbps | kbps | mbps | pps}'
I understand overall what is happening. Question I have is why and how this works. I can find shaping for other switch types, but not these specific commands. Typically I've seen shaping on an average throughput.
What effect does minimum have? Is that the minimum size reserved for a queue? As in, even if another queue is over its limit, this one will always be guaranteed that minimum amount? Or is that the minimum size that it starts shaping packets?
For maximum, is that the maximum it will shape to, the maximum size of the queue, or something else? Can the maximum shape size exceed the percentage bandwidth of the link (or is that even good practice)?
Here's roughly what I was playing with in a lab setup (not showing class-maps/ACLs/etc.). I'm not doing priority queuing here, that's why its removed on q3. This is on a 1Gbps link outbound. I set the max total past the size of think link and it takes the commands and shows it when I look at the policy map on the interface.
Policy-map type queuing Egress_QoS_Policy
class type queuing c-out-q3
bandwidth percent 10
shape min 40 mbps max 110 mbps
class type queuing c-out-q2
bandwidth percent 30
shape min 200 mbps max 330 mbps
class type queuing c-out-q1
bandwidth percent 50
shape min 300 mbps max 550 mbps
class type queuing c-out-q-default
bandwidth percent 10
shape min 40 mbps max 100 mbps
