[c-nsp] Hierarchical QoS Policies

[Rodney Dunn]

> it that does LLQ. I would at least expect a difference.
>  
> > > I have not found detailed documentation about the shaper and how it
> > > interacts with LLQ so far, any pointers are welcome.
> > 
> > there were a similar thread last december on this mailing list. rodney dunn
> > posted some explanations how shaping works.
> 
> Yeah, thanks, found that back in my mailbox (I've even read it then)
> and reread it. Rodney essentially explains that LLQ under a shaper would
> give better latency than just the shaper or a shaper with just "bandwidth"
> child policies. I'd just like to be able to proof that in my lab...

I have been behind on email lately and too lazy to go back and read
the entire thread.

What are you testing?

An email from a co-worker much more knowledgeable in broadband
than I am had sent this:

 
-=-
1) Qos is not supported on VA for L2TP tunnels
2) with PPPoX (maybe others), hierarchical MQC does not work (shaping not
supported)
3) with PPPoX, One can only have (non hierarchical) qos working on dialer
or virtual-template AND only with MLP.

QoS over dsl:
=============

So, when a customer requests to enable qos on his cpe running PPPoX, he
has 2 options :

A) The easy one :
enable vbr (rt or nrt) or cbr atm shaping on the atm pvc and apply the
queueing service-policy directly on the pvc.  Note, without vbr
(rt or nrt) or cbr, qos is not supported on ATM.  See also :
http://www.cisco.com/warp/customer/121/7200_per-vc-CBWFQ.html

One note here which may save you some headaches is to not forget to tune
the tx-ring-limit for the ATM pvc (as it is not done
automagically as for normal interfaces) :
http://www.cisco.com/warp/public/121/txringlimit_6142.html

B) The complicated way :
enable mlp on the dialer on the CPE, and apply the QoS there.  But then
mlp needs to be negotiated with whoever terminates the ppp.  This
needs involvement of the dsl provider, as his UAC will need to have mlp
enabled under its virtual template as well.

And if this is vpdn, he will need to enable mlp on both LAC and LNS,
except if there is LCP renegotiation configured.  In case of the
latter, mlp only needs to be enabled on the LNS.  


There is the following doc on CCO, but it is pretty incomplete :
http://www.cisco.com/warp/customer/105/pppoe_qos_dsl.html


There are some feature request in to make per-user shaping and
queueing work. I don't know the timeline.

Rodney


> 
> Thanks,
> Andre.
> -- 
>                   The _S_anta _C_laus _O_peration
>   or "how to turn a complete illusion into a neverending money source"
> 
> -> Andre Beck    +++ ABP-RIPE +++    IBH Prof. Dr. Horn GmbH, Dresden <-
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