[c-nsp] QOS on asr901

[Pshem Kowalczyk]

Hi,

ASR901 has a very odd qos implementation due to the fact it's based on a
stock-standard Broadcom chip. From my experience - only basic stuff
actually works (regardless of what docs say). On a single port you can
effectively have only one egress policy (regardless of the number of the
EVCs you have), ingress direction allows you one policy per EVC. The only
classifier on egress is qos-group (that you have to set on ingress).

>From my experience - it can be made to work on the policing (ingress),
shaping/scheduling (egress) front, but requires a lot of testing and
experimentation. For example - I've noticed that If you try to modify some
qos settings on a map already applied to an interface/evc - it gets
detached quietly, but remains in the config as if it was ok. Also - the
whole EVC has to be nuked if you want to modify a policy to make sure it
actually gets applied correctly (it helps to modify the service instance
id).
If you think your core link might congest - pay close attention to the
markings of control plane packets - we've seen links drop because BFD
wasn't scheduled as priority.

I was told that next revision will use a better chipset, but I don't know
the timeframes.

Have you considered an ME1200 (if you don't need the 10G)?
http://www.cisco.com/c/en/us/products/switches/me-1200-series-carrier-ethernet-access-devices/index.html

kind regards
Pshem




On 21 June 2014 02:15, Vitkovský Adam <adam.vitkovsky at swan.sk> wrote:

> Hi folks,
>
> I'm just evaluating asr901 and came across some QOS issues.
> Anyone using egress QOS with priority and random-detect
> discard-class-based on ASR901 please?
> I'm getting so many errors and limitations.
>
> Had to strip the priority queue config to basically this:
> class core_realtime
>   priority percent xx
>
> -as it seems you can't use police even though the queue is marked as
> priority -though the documentation says it's possible.
>
> And even than I got this errors
> Jun 20 21:21:46.562:  Data Qualify failed(2):-7
> Jun 20 21:21:46.562:  Error in programming Exp:-7
>
> I guess it's because of
> class class-default
>   random-detect discard-class-based
>   random-detect discard-class 0 20 30 10
>
> Also are there any plans for supporting QOS under service instances please?
>
> Thank you
>
>
> adam
>
>
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>