How do you verify WRED configuration on a router

To verify WRED (Weighted Random Early Detection) configuration on a router, you can use the following commands:

Show queueing random-detect:

   Router# show queueing random-detect

This command displays the WRED configuration and statistics for all interfaces[3]. The output includes:

• Queueing strategy – Indicates that WRED is the active queueing strategy
• Exponential weight constant – Shows the weight used for calculating the average queue size.
• Mean queue depth – Displays the current average queue size.
• Class-specific information (minimum/maximum thresholds, mark probability) – Includes minimum and maximum thresholds, as well as the mark probability for different traffic classes.
• Packet drop statistics – Provides data on the number of packets dropped due to WRED.

Show policy-map interface:

   Router# show policy-map interface INTERFACE

This command shows the QoS policy configuration and statistics for a specific interface, including WRED settings if configured within a policy[3].

Show interfaces:

   Router# show interfaces [type slot/port]

This command displays interface statistics and configuration, including WRED information if enabled on the interface[1].

Show queue:

   Router# show queue interface-type interface-number

This command shows the header information of packets inside a queue, which can be useful for troubleshooting WRED behavior[1].

Show queueing interface:

   Router# show queueing interface interface-number [vc [[vpi/] vci]]

This command displays WRED statistics for a specific virtual circuit (VC) on an interface[1].

When examining the output, look for:

• Confirmation that WRED is enabled
• Correct thresholds and drop probabilities for different traffic classes
• Proper exponential weight constant
• Expected packet drop behavior

Remember that the exact command syntax and output may vary slightly depending on your router model and IOS version.

Citations:
[1] https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_conavd/configuration/xe-16/qos-conavd-xe-16-book/qos-conavd-cfg-wred.html
[2] https://support.hpe.com/techhub/eginfolib/networking/docs/routers/msrv5/cg/5200-2309_acl-qos-cg/content/462306113.htm
[3] https://ccie.nyquist.eu/qos/congestion-avoidance-wred
[4] https://www.nytimes.com/wirecutter/blog/modem-vs-router/
[5] https://www.ics.agh.edu.pl/dydaktyka/mm/lato0405_inf_d/laboratoria/QoS/qcfwred.pdf
[6] https://www.ciscopress.com/articles/article.asp?p=352991&seqNum=8
[7] https://www.reddit.com/r/HomeNetworking/comments/wz93zx/is_a_new_router_just_plug_and_play/
[8] https://www.juniper.net/documentation/us/en/software/junos/traffic-mgmt-qfx/topics/example/tail-drop-profiles-cos-configuring.html