[j-nsp] A conceptual advice on QoS is needed

[Adam Vitkovsky]

> Victor Sudakov
> Sent: Wednesday, February 17, 2016 7:34 AM
>
> Colleagues,
>
> We have Juniper switches interconnected by a transport network (NEC
> equipment mostly). The nodes of the transport network are Ethernet
> switches in their own right, they have 4 or 8 interface queues and can do
> priority queueing and/or WRR queueing based on 802.1p codepoints in
> received frames.
>
> Now if you had to implement QoS policies, where would you do the actual
> prioritization:
>
> 1. Classify the frames on the Juniper switches, but do the actual
> queueing/prioritization in the transport network.
>
> 2. Configure one FIFO queue on the transport network nodes and do both
> classification and prioritization on the switches.
>
> It may be important to know that most switches are connected to the
> transport network by Gigabit interfaces, but the real throughtput of the
> transport network itself is about 150 Mbit/s.
>
> But there is another branch of the transport network where all interfaces on
> the nodes are 100BaseT, so the switches are connected at
> 100 Mbit/s.
>
> Thanks in advance for any opinions.
>
Victor,

If your network carries traffic of higher priority that is interleaved with traffic of lower priority then the below questions are relevant:

1) Can it happen on Juniper switches that BW on input > BW on output  (e.g. traffic incoming on multiple ports will be transmitted out one port)?
If yes then you need QOS (classification and scheduling)

2) Can it happen on NEC transport switches that BW on input > BW on output?
If yes then you need QOS (classification and scheduling)

adam


        Adam Vitkovsky
        IP Engineer

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