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  • 1.  Shaping on downlink interface to avoid packet drops on uplink

    Posted 06-07-2022 05:17
    Hi!

    Regarding shaping on downlink interface to avoid packet drops on uplink interfaces,
    I have a few questions:

    On a default configured JunOS SRX router(1500/550):

    1/There is no default shaping-rate applied to physical interface
    ->That means that if the queues BE and NC are full, packets will drop.

    Is my understanding correct?

    2/To remedy that, when your uplink is nearly 100% used,
    it is safer to set up a shaping policy on your downlink(ingress direction).

    Is my understanding correct?

    3/I am planning to set up the following shaping Class of Service
    (to be accurate, no classification, only shaping my downlink,
    in the ingress direction, to protect my uplink, in the egress direction).

    For that, I am planning to configure an input shaper on the logical interface.
    I have many logical interfaces but only a few of them
    are handling most of the traffic.
    For that reason, I will apply the input shaper only on the logical interfaces
    that are handling most of the traffic.

    user@host# edit class-of-service interfaces interface-name unit logical-unit-number
    user@host# set input-shaping-rate (percent percentage | rate)

    edit class-of-service interfaces reth2 unit 333
    set input-shaping-rate percent 25
    edit class-of-service interfaces reth2 unit 181
    set input-shaping-rate percent 25
    edit class-of-service interfaces reth2 unit 222
    set input-shaping-rate percent 25

    edit class-of-service interfaces reth2 unit 2038
    set input-shaping-rate 25

    Is my understanding correct?

    4/Also, I am not using the physical interface(downlink/ingress)
    because I have 2 uplinks/egress interfaces.
    The same physical interface(downlink/ingress) is using both uplinks interfaces.
    Some of the logical downlink interfaces are going to one of the uplink interfaces,
    and other logical downlink interfaces are going to the other uplink interface.

    5/Finally, I am wondering what will be the effect when
    those logical interfaces reach the 25% input-shaping-rate.
    Do users will experience a severe transmit speed degradation?
    *Currently those interfaces are at times running at nearly 100%
    of the interface bandwidth(not at the same time though).

    TIA,

    ------------------------------
    FRED ELLENA
    ------------------------------


  • 2.  RE: Shaping on downlink interface to avoid packet drops on uplink

    Posted 06-28-2022 02:07
    Hi!

    I am wondering if somebody has a few answers for me!

    TIA!

    ------------------------------
    FRED ELLENA
    ------------------------------