QoSPrivileged EXEC

show traffic-shape

Displays traffic shaping configuration and statistics for all interfaces or a specific interface, used to verify shaping parameters and monitor traffic conformance.

Syntax·Privileged EXEC

show traffic-shape

When to Use This Command

Verify that traffic shaping is enabled and correctly configured on a WAN interface after deployment.
Monitor whether traffic is being shaped (delayed) or dropped due to shaping limits during congestion.
Troubleshoot slow application performance suspected to be caused by excessive traffic shaping.
Check the number of packets queued or delayed by shaping on a customer-facing interface.

Command Examples

Basic show traffic-shape output

show traffic-shape

Interface   Se0/0/0
       Access Target    Byte   Sustain   Excess    Interval  Increment Adapt
VC     List   Rate      Limit  bits/int  bits/int  (ms)      (bytes)   Active
-      -      256000    16000  16000     16000     125       4000      -

Queueing Stats:
        Queue     Packets   Bytes     Packets   Bytes     Delayed  Delayed
        Depth     Delayed   Delayed   Dropped   Dropped   (ms)     (ms)
        0         0         0         0         0         0        0

The output shows shaping parameters for Serial0/0/0: Target Rate is 256000 bps, Byte Limit is 16000 bytes, Sustain and Excess bits are both 16000, Interval is 125 ms, Increment is 4000 bytes. Queueing stats show no packets delayed or dropped, indicating no congestion.

Show traffic-shape with active shaping

show traffic-shape interface serial 0/0/0

Interface Se0/0/0
       Access Target    Byte   Sustain   Excess    Interval  Increment Adapt
VC     List   Rate      Limit  bits/int  bits/int  (ms)      (bytes)   Active
-      -      128000    8000   8000      8000      125       2000      -

Queueing Stats:
        Queue     Packets   Bytes     Packets   Bytes     Delayed  Delayed
        Depth     Delayed   Delayed   Dropped   Dropped   (ms)     (ms)
        12        150       24000     5         800       45       120

Shaping is active with a target rate of 128 kbps. Queue depth of 12 indicates packets are being queued. 150 packets delayed with average delay 45 ms, and 5 packets dropped due to shaping. This suggests the interface is congested and shaping is throttling traffic.

Understanding the Output

The output is divided into two sections: shaping parameters and queueing statistics. The first section shows per-interface or per-VC shaping configuration: Target Rate (bps), Byte Limit (maximum bytes per interval), Sustain and Excess bits (CIR and Be), Interval (Tc in ms), Increment (bytes sent per interval), and Adapt (whether adaptive shaping is active). The second section shows queueing stats: Queue Depth (current number of packets in the shaping queue), Packets Delayed/Dropped (cumulative counts), Bytes Delayed/Dropped, and Delayed (ms) showing average delay and total delay. High queue depth or increasing delayed/dropped packets indicates shaping is actively limiting traffic. Zero values mean no shaping activity. Watch for sustained queue depth above 0 or increasing drops, which may indicate the configured rate is too low for the traffic.

CCNA Exam Tips

CCNA exam tip: The 'show traffic-shape' command does not show policing statistics; it is only for shaping. Policing uses 'show policy-map interface'.

CCNA exam tip: Remember that shaping queues packets and delays them, while policing drops or marks packets. This command helps verify queuing behavior.

CCNA exam tip: The 'Byte Limit' is calculated as (Target Rate * Interval) / 8. Exam may ask you to compute this or interpret the values.

CCNA exam tip: If 'Adapt' shows 'Yes', the router is using BECN or FECN to adjust shaping rate on Frame Relay interfaces.

Common Mistakes

Mistake 1: Confusing shaping with policing. Shaping delays packets; policing drops. Use 'show traffic-shape' for shaping, not policing.

Mistake 2: Forgetting to specify the interface when troubleshooting a specific link. Without interface, output shows all interfaces, which may be overwhelming.

Mistake 3: Misinterpreting 'Queue Depth' as the number of packets dropped. Queue depth is the current number of packets waiting; drops are shown separately.

Related Commands

show interfaces

Displays detailed status and statistics for all interfaces or a specific interface, used to verify interface operational state, errors, and performance.

show policy-map interface

Displays the current QoS policy applied to an interface, including per-class statistics such as packets matched, bytes, and actions taken, used to verify and troubleshoot QoS configurations.

Practice for the CCNA 200-301

Test your knowledge with hundreds of CCNA practice questions covering all exam domains.

Practice CCNA Questions