[j-nsp] delay-buffer in Juniper

[Huan Pham]

>
>
> Honestly, that's 9.5 documentation. Perhaps something changed at some
> point, but in current versions of code this is not how it works.
>
>


Hi Stefan,

You are right, I should to pay attention to the version, as the behaviour
may have changed. I am new to Juniper (moving from the Cisco background),
so I am still not familiar with navigating Juniper documentation. I relied
on Google first hit :) . Will try to navigate the Juniper documentation.

However, for this feature in the newest OS, I do not think that the
behaviour is as you described. Although worded differently, it basically
means the same as the one I quoted:

Here's the link to the 12.1 OS:

http://www.juniper.net/techpubs/en_US/junos12.1/topics/reference/configuration-statement/transmit-rate-edit-cos.html

rate-limit—(Optional) Limit the transmission rate to the rate-controlled
amount. In contrast to the exact option, the scheduler with the rate-limit
option shares unused bandwidth above the rate-controlled amount.


I do not always trust the documentation, especially there may be limitation
with hardware platform, OS version etc that is not well documented, so I
set up a quick lab (running version 11.4R5.5) to test this feature. The
behaviour in this case is the same as documented.


When I use transmit-rate rate-limit I can send more traffic than the
transmit rate-controlled amount. The transmit-rate rate-limit is 1m, but I
can send traffic at 8Mbps.

When I use transmit-rate exact I can not send more traffic than the
transmit rate-controlled amount.

One side note though, when I set the rate to a very low number (e.g. 10k,
or even 500k), and use the "exact" option, the actual transmuted rate (on
1Gbps port) is not rate limited to the configured value. This is probably
understandable, due to factors as sampling intervals etc.

Here's my lab config and results:


         ge-1/0/0                ge-1/1/0
(MX5) R1 -------------------------------- R2 (Virtual)
         10.1.1.1                10.1.1.2


I generated traffic by pinging from R2 to R1
lab at MX5> ping 10.1.1.1 routing-instance R2 rapid count 100000 size 1000

(Ping from R2 to R1, and monitor traffic on outbound of R1)




lab at MX5> show configuration class-of-service schedulers admin-sched
transmit-rate {
    1m;
    rate-limit;
}
buffer-size percent 10;
priority medium-low;



lab at MX5> show interfaces queue ge-1/1/0 | find admin
Queue: 1, Forwarding classes: admin
  Queued:
    Packets              :                 75751                   931 pps
    Bytes                :              80750566               7942744 bps
  Transmitted:
    Packets              :                 75751                    931 pps
    Bytes                :              80750566               7942744 bps
    Tail-dropped packets :                     0                     0 pps
    RED-dropped packets  :                     0                     0 pps
     Low                 :                     0                     0 pps
     Medium-low          :                     0                     0 pps
     Medium-high         :                     0                     0 pps
     High                :                     0                     0 pps
    RED-dropped bytes    :                     0                     0 bps
     Low                 :                     0                     0 bps
     Medium-low          :                     0                     0 bps
     Medium-high         :                     0                     0 bps
     High                :                     0                     0 bps



Change to using "exact", I can not send more than 1M as expected.

lab at MX5> show configuration class-of-service schedulers admin-sched
transmit-rate {
    1m;
    exact;
}
buffer-size percent 10;
priority medium-low;



lab at MX5> show interfaces queue ge-1/1/0 | find admin
Queue: 1, Forwarding classes: admin
  Queued:
    Packets              :                 14288                   116 pps
    Bytes                :              15231008                994928 bps
  Transmitted:
    Packets              :                 14288                    116 pps
    Bytes                :              15231008                994928 bps
    Tail-dropped packets :                     0                     0 pps
    RED-dropped packets  :                     0                     0 pps
     Low                 :                     0                     0 pps
     Medium-low          :                     0                     0 pps
     Medium-high         :                     0                     0 pps
     High                :                     0                     0 pps
    RED-dropped bytes    :                     0                     0 bps
     Low                 :                     0                     0 bps
     Medium-low          :                     0                     0 bps
     Medium-high         :                     0                     0 bps
     High                :                     0                     0 bps





FULL CONFIG
-----------



lab at MX5> show configuration class-of-service
forwarding-classes {
    queue 0 best-effort;
    queue 1 admin;
    queue 2 voip;
    queue 3 network-control;
}
interfaces {
    ge-1/0/0 {
        scheduler-map my-sched-map;
    }
    ge-1/1/0 {
        scheduler-map my-sched-map;
    }
}
scheduler-maps {
    my-sched-map {
        forwarding-class best-effort scheduler best-effort-sched;
        forwarding-class admin scheduler admin-sched;
        forwarding-class voip scheduler voip-sched;
        forwarding-class network-control scheduler network-control-sched;
    }
}
schedulers {
    best-effort-sched {
        transmit-rate 40k;
        buffer-size percent 40;
        priority low;
    }
    /* PING packets are subject of this scheduler */
    admin-sched {
        transmit-rate {
            1m;
            rate-limit;
        }
        buffer-size percent 10;
        priority medium-low;
    }
    voip-sched {
        transmit-rate percent 10;
        buffer-size percent 10;
        priority high;
    }
    network-control-sched {
        transmit-rate percent 5;
        buffer-size percent 5;
        priority medium-high;
    }
}






lab at MX5# show firewall
family inet {
    filter RE-Generated-Classifier {
        term OSPF {
            from {
                protocol ospf;
            }
            then {
                forwarding-class network-control;
                dscp cs7;
            }
        }
        term ICMP {
            from {
                protocol icmp;
            }
            then {
                forwarding-class admin;
                dscp cs1;
            }
        }
        /* Keep default behaviour */
        term OTHERS {
            then accept;
        }
    }
}



lab at MX5# show
/* This loopback belong to the Master Router */
unit 0 {
    family inet {
        filter {
            output RE-Generated-Classifier;
        }
    }
}
/* This loopback belong to Virtual Router R2 */
unit 2 {
    family inet {
        filter {
            output RE-Generated-Classifier;
        }
    }
}


lab at MX5# show routing-instances
R2 {
    instance-type virtual-router;
    interface ge-1/1/0.0;
    interface lo0.2;
    routing-options {
        router-id 10.1.1.2;
    }
    protocols {
        ospf {
            area 0.0.0.0 {
                interface ge-1/1/0.0;
            }
        }
    }
}


lab at MX5# show protocols ospf
area 0.0.0.0 {
    interface ge-1/0/0.0;
}