[c-nsp] QoS per ethernet subif

[Frédéric Jutzet]

> Does priority traffic compete with traffic from the same subinterface
only 
> (where the policy is applied), or does it compete with 
> the whole traffic passing through all subinterfaces?

if you apply it on a subif, it will compete only on this subif


> Does it make sense to use priority on the default class or should i
use 
> another class for matching all traffic?

> Does it make sense to use priority when there is only one class
defined for 
> the subif's policy?


the priority will only guaranty you that you have 3000k for the pk that
match your criteria, and only when the queue is full (in that case the
virtual queue created by the shaper), which mean in that case only when
you reach the 4M you have define in the shaper. That mean as soon as you
reach 4M on your shaper, you will then garanty 3M for all
traffic...Based on the 1st answer, you see that make no sense.




maybe you can apply your police-map on the main intf instead of subif,
but based on different criteria, 

router7200(config-cmap)#match ?
  access-group         Access group
  any                  Any packets
  class-map            Class map
  cos                  IEEE 802.1Q/ISL class of service/user priority
values  <<<<<<<<<
  destination-address  Destination address      <<<<<<<<<<<<<
  discard-class        Discard behavior identifier
  dscp                 Match DSCP in IP(v4) and IPv6 packets
  fr-de                Match on Frame-relay DE bit
  fr-dlci              Match on fr-dlci
  input-interface      Select an input interface to match     
<<<<<<<<<<<
  ip                   IP specific values
  mpls                 Multi Protocol Label Switching specific values
  not                  Negate this match result
  packet               Layer 3 Packet length
  precedence           Match Precedence in IP(v4) and IPv6 packets
  protocol             Protocol
  qos-group            Qos-group
  source-address       Source address       <<<<<<<<<<<<<<


But in my opinion, it's even better if you set a cos/dscp in the pk on
your egress router/switch, then it's easier to match which pk get
prioritised on your congested intf.

Rgds.
-Frédo



>>> On 27.09.2007 at 17:59, in message <46FBD346.30900 at forthnet.gr>,
Tassos
Chatzithomaoglou <achatz at forthnet.gr> wrote:
> Hi,
> 
> After reading 
>
http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a00801

> 14326.shtml
> i'm trying the following config on a 7200-G1 (12.2(31)SB7) and i was

> wondering if there is any actual reason to use it.
> 
> !---------------------------------
> policy-map TEST-POLICY
>    class class-default
>      shape average 4000000
>     service-policy TEST-POLICY-CHILD
> !
> policy-map TEST-POLICY-CHILD
>    class class-default
>      priority 3000
>    set cos 5
> !
> interface GigabitEthernet0/2.2
>   encapsulation dot1Q 2
>   ip address y.y.y.y
> !
> interface GigabitEthernet0/2.3
>   encapsulation dot1Q 3
>   ip address x.x.x.x
>   service-policy output TEST-POLICY
> !---------------------------------
> 
> Gi0/2 is connected to a 6500 and has ~10 subinterfaces like the
above.
> I want all traffic passing from specific subinterfaces to have
priority over 
> traffic passing from the other subinterfaces.
> 
> So...
> Does it make sense to use priority on the default class or should i
use 
> another class for matching all traffic?
> Does it make sense to use priority when there is only one class
defined for 
> the subif's policy?
> Does priority traffic compete with traffic from the same subinterface
only 
> (where the policy is applied), or does it compete with 
> the whole traffic passing through all subinterfaces?
>