The customer wanted to monitor tail drops on the MX interfaces using Telemetry.
Topology:(IXIA)S0:50%---| |------DUT--------------D0(IXIA)S1:60%---|
Physical interface: xe-0/0/1, Enabled, Physical link is Up Interface index: 161, SNMP ifIndex: 608 Forwarding classes: 16 supported, 6 in use Egress queues: 8 supported, 6 in use Queue: 5, Forwarding classes: af3 Queued: Packets : 0 0 pps Bytes : 0 0 bps Transmitted: Packets : 0 0 pps Bytes : 0 0 bps Tail-dropped packets : 0 0 pps RL-dropped packets : 0 0 pps RL-dropped bytes : 0 0 bps 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 Queue-depth bytes : Average : 32126 Current : 0 Peak : 32768 Maximum : 32768 ---(refreshed at 2024-07-02 22:43:57 PDT)--- Physical interface: xe-0/0/1, Enabled, Physical link is Up Interface index: 161, SNMP ifIndex: 608 Forwarding classes: 16 supported, 6 in use Egress queues: 8 supported, 6 in use Queue: 5, Forwarding classes: af3 Queued: Packets : 0 0 pps Bytes : 0 0 bps Transmitted: Packets : 0 0 pps Bytes : 0 0 bps Tail-dropped packets : 0 0 pps RL-dropped packets : 0 0 pps RL-dropped bytes : 0 0 bps 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 Queue-depth bytes : Average : 32126 Current : 0 Peak : 32768 Maximum : 32768 ---(refreshed at 2024-07-02 22:44:02 PDT)--- Physical interface: xe-0/0/1, Enabled, Physical link is Up Interface index: 161, SNMP ifIndex: 608 Forwarding classes: 16 supported, 6 in use Egress queues: 8 supported, 6 in use Queue: 5, Forwarding classes: af3 Queued: Packets : 16967759 4296262 pps Bytes : 5429682880 10998433280 bps Transmitted: Packets : 15425432 3905697 pps Bytes : 4936138240 9998584320 bps Tail-dropped packets : 981008 248432 pps RL-dropped packets : 0 0 pps RL-dropped bytes : 0 0 bps RED-dropped packets : 561319 142133 pps Low : 561319 142133 pps Medium-low : 0 0 pps Medium-high : 0 0 pps High : 0 0 pps RED-dropped bytes : 179622080 363861760 bps Low : 179622080 363861760 bps Medium-low : 0 0 bps Medium-high : 0 0 bps High : 0 0 bps Queue-depth bytes : Average : 32126 Current : 0 Peak : 32768 Maximum : 32768 ---(refreshed at 2024-07-02 22:44:07 PDT)--- Physical interface: xe-0/0/1, Enabled, Physical link is Up Interface index: 161, SNMP ifIndex: 608 Forwarding classes: 16 supported, 6 in use Egress queues: 8 supported, 6 in use Queue: 5, Forwarding classes: af3 Queued: Packets : 34155410 4296361 pps Bytes : 10929731200 10998686720 bps Transmitted: Packets : 31050586 3905788 pps Bytes : 9936187520 9998817280 bps Tail-dropped packets : 1974361 248266 pps RL-dropped packets : 0 0 pps RL-dropped bytes : 0 0 bps RED-dropped packets : 1130463 142307 pps Low : 1130463 142307 pps Medium-low : 0 0 pps Medium-high : 0 0 pps High : 0 0 pps RED-dropped bytes : 361748160 364307200 bps Low : 361748160 364307200 bps Medium-low : 0 0 bps Medium-high : 0 0 bps High : 0 0 bps Queue-depth bytes : Average : 32231 Current : 32560 Peak : 32768 Maximum : 32768 ---(refreshed at 2024-07-02 22:44:12 PDT)--- Physical interface: xe-0/0/1, Enabled, Physical link is Up Interface index: 161, SNMP ifIndex: 608 Forwarding classes: 16 supported, 6 in use Egress queues: 8 supported, 6 in use Queue: 5, Forwarding classes: af3 Queued: Packets : 59948585 4297890 pps Bytes : 19183547200 11002599680 bps Transmitted: Packets : 54498951 3907178 pps Bytes : 17439664320 10002375680 bps Tail-dropped packets : 3464920 248532 pps RL-dropped packets : 0 0 pps RL-dropped bytes : 0 0 bps RED-dropped packets : 1984714 142180 pps Low : 1984714 142180 pps Medium-low : 0 0 pps Medium-high : 0 0 pps High : 0 0 pps RED-dropped bytes : 635108480 363980800 bps Low : 635108480 363980800 bps Medium-low : 0 0 bps Medium-high : 0 0 bps High : 0 0 bps Queue-depth bytes : Average : 32231 Current : 32560 Peak : 32768 Maximum : 32768 ---(*more 100%)---[abort] labroot@jre0> show interfaces queue xe-0/0/1 forwarding-class af3 | refresh 5 | match Tail-dropped ---(refreshed at 2024-07-02 22:44:27 PDT)--- Tail-dropped packets : 6940605 248212 pps ---(refreshed at 2024-07-02 22:44:32 PDT)--- Tail-dropped packets : 8430556 248436 pps ---(refreshed at 2024-07-02 22:44:37 PDT)--- Tail-dropped packets : 9424274 248390 pps ---(*more 100%)---[abort]
This article provides instructions on how to achieve tail drops on an MX device and verify them through telemetry. Tail drops occur when a queue is full, and incoming packets are dropped. This behavior can be configured and monitored using specific QoS settings and TOS values on the MX device.
To configure the MX device for tail drops, use the following commands:
set class-of-service traffic-control-profiles qos-control-profile scheduler-map qos-scheduler-trio-cassisset class-of-service traffic-control-profiles qos-control-profile shaping-rate percent 10 ===> to make queue very less
This configuration sets the traffic control profiles and adjusts the shaping rate to make the queue smaller, thereby facilitating tail drops.
We conducted tests on tail drops for the AF3 forwarding class using the TOS (Type of Service) field value 011 in the IPv4 header. To view and verify tail drops for other queues via telemetry, you need to include the corresponding TOS value in the IPv4 address.
011
Below are the TOS values for each forwarding class and their respective loss priorities:
000
001
010
100
101
110
111
By following the above configuration and using the provided TOS values, you can achieve and verify tail drops on the MX device through telemetry. This setup ensures that packets are dropped when the queue is full, allowing you to observe and manage network traffic effectively.