Simple QoS Policy On 877

[Blakeexz]

I have a simple qos policy that has 2 x class-maps for traffic differentiation, call them Fred and Ginger.

The class-maps call 2 x access lists say 100 & 101. In each there are a
couple of entries for source and destination traffic, so far so good.

I assign the class maps to a policy map as such:

policy-map cpe-to-pe
class Fred
set ip dscp ef
class Ginger
set ip prec 2
class class-default
fair-queue

I assign said policy to my ATM PVC.

int atm0
pvc 0/38
service-policy output cpe-to-pe

When testing I see values for my 'offered rates' & matches on the QoS ACL's but no packet marking takes place. I can't understand why...anyone any ideas.From previous reading I don't believe the QoS settings should be assigned to the dialer. I note when doing this though I get packets marked, although strangely only for the Di0 and not for virtual-access 2 .

Regards

[Oswald]

I have done quite a bit of experimentation andtesting on QoS on DSL with 877 routers.Mostly with no success.I wrote the most of this first then read your policy map in detail Hmmm.. since you do not actually want to drop traffic in your policy map you should have no problems just applying this to the dialer.One thing - I am not sure that dscp and IP prec are exactly compatible? Well they are all just bits but it seems unnecessarily confusing. As I understand it dhcp supperceeds the use of the field for IP prec/whatever the other bit was called. I would stick to one or the other.

If you do want to drop exessive traffic:-

One thing that did seem to work was:

pvc 0/38
vbr-nrt 448 448 ! tell ATM to "back pressure" to dialer
! when tx queue full
tx-ring-limit 2 ! if you dont change this from default
! (of 16?) too many packets are on the outside of
the
! QoS processing for any decent effect.
! This is 2 IP PACKETS not ATM cells - I
understand.

Then you apply your policy map to the Dialer.Note that as I understand it you cannot use hierarchical policy maps on the 87x so cannot do traffic shaping. Or maybe there is some other reason that traffic shaping cannot be done AT ALL on DSL at least on this platform. As a sort of aside - I would not have thought that the IP based policy map would have worked on the ATM interface UNLESS it had IP enabled on it. Comments on this particularly welcome.

I have not tried the latest 12.4(20 is it?)T

You clearly need to choose the appropriate vbr-nrt numbers for your uplink speed. Finally there are some tantalising references in
the documentation to QoS over MLPPP over DSL. Never tried it. It might be worth searching past messages on comp.dcom.sys.cisco that I have posted.

[Philip21]

pvc 0/38
cbr 288 (I was going to go with vbr-rt originally, and I note you use nrt).
txt-ring-limit 3

Interesting you say that you apply your policy-map to the dialer. I will have a look at this again as packets were marked OK, however, when you do a show policy-map int you will see details for the dialer and the virtual-access line cloned with the dialer. On the latter it gives a different reading, however, I am unsure of the significance.I will look up the MLPPP over DSL reference and dig about in previous postings. I reckoned to have searched before my sending my post but wasn't paying attention by the look of it