[j-nsp] Class of Service Question

Harry Reynolds harry at juniper.net
Wed Jan 6 14:50:52 EST 2010

Sounds like a case for per-unit scheduling/shaping, which is possible on IQ/Iq2 interfaces. However, I'm confused by the comment of one vlan w/both voice and data. Here that is one unit, which you can shape to less than the physical rate, but to then provide bandwidth to one app vs another within that ifl I think you will need a MF classifier and related policer function as well.


<<< typical per unit scheduler/shaper, needs Iq pic:

>         [edit interfaces] 
>         ge-1/0/0 { 
>             vlan-tagging; 
>             per-unit-scheduler; 
>         }
>         Under the class-of-service interface stanza:
>         [edit class-of-service] 
>         interfaces { 
>             ge-1/0/0 { 
>                 unit 50 { 
>                     scheduler-map vlan50; 
>                     shaping-rate 50m; 
>                 } 
>                 unit 60 { 
>                     scheduler-map vlan60; 
>                     shaping-rate 60m; 
>                 } 
>             } 
>         }

-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Eric Van Tol
Sent: Wednesday, January 06, 2010 11:38 AM
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] Class of Service Question

Hi all,
I'm having a bit of a time figuring out how to do QoS for a particular type of setup.  I currently have some excellent working configs for channelized IQ interfaces and full FE/GE interfaces.  My problem at this point is trying to figure out how to do QoS for logical interfaces on a GE port.  My problem comes from the fact that QoS appears to work based upon the bandwidth of the physical interface, not the logical interface.

For instance, we have a need to provide voice services to customers through a Gigabit ethernet connection via another provider, using EoC for the last mile.  All customers will be provisioned on a separate VLAN.  With plain ethernet implementations, we've simply used two VLANs - one for voice and one for data.  However, in this case, we are being given only a single VLAN on which both voice and data will traverse.

My primary question is when configuring schedulers, how do I let the router know that logical interface A is only a 10M circuit and interface B is a 25M circuit?  When specifying that I need a certain amount of bandwidth available for traffic type X on a 10m logical unit, doesn't JUNOS see that the interface bandwidth is 1G and therefore never really implement any queuing because the full interface bandwidth and queues will likely never really be full?  Or does the 'shaping-rate' in the virtual-channel configuration clue the router in to the actual rate of the logical unit?

I recall, perhaps mistakenly, that IOS had the 'bandwidth' command in the interface config that not only worked for IGP calculations, but also clued the QoS config into knowing that an interface really only had X amount of bandwidth and not what was reported by the interface itself.  Doesn't look like Juniper's "equivalent" does this, at least from what I can gather from the docs.

Any advice from anyone who's done a similar setup would really be appreciated.

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