Configuring User-Defined Traffic Classes



These commands are available to configure custom CPU classes that are added to the default list (shown in previous section) in order to address special user requirements:


To add a CPU class, use the command:


CLI (network-admin@switch) > cpu-class-create


name

Specify a name for the CPU class.

scope local|fabric

Specify the scope as local or fabric.

rate-limit rate-limit-number

Specify the cap for the rate limit.

hog-protect disable|enable|enable-and-drop

Specify if you want to enable, enable and drop packets, or disable hog protection.

                                             


The cpu-class-create command can be used to allocate new CPU traffic queues for special cases that are identified by user-configurable policies.


For instance, when the culprit of a high CPU utilization issue is being investigated in connection with an errant traffic flow (e.g., FTP), the Arista TAC team may recommend configuring a user-defined traffic class with an associated policy to protect the CPU.


In this example a new class TAC-class is created and associated to a rate of 100 pps and automatically allocated to free queue 40:


CLI (network-admin@switch) > cpu-class-create name TAC-class scope local rate-limit 100


CLI (network-admin@switch) > cpu-class-show name TAC-class


name      scope rate-limit hog-protect  hog-protect-support queue

-------   ----- ---------- -----------  ------------------- -----

TAC-class  local 100        disable      none                40


TAC also requests to create/modify a vFlow policy to direct FTP packets to the new CPU class (TAC-class) queue. vFlow match criteria can be freely chosen to match the specific rate limiting need of the user provided they include a to-cpu or copy-to-cpu action for packets:


CLI (network-admin@switch) > vflow-create name myflow scope local in-port 10 proto ftp action to-cpu cpu-class TAC-class


CLI (network-admin@switch) > vflow-show


name   scope type  in-port burst-size precedence action enable cpu-class

------ ----- ----- ------- ---------- ---------- ------ ------ ---------

myflow local vflow  10     auto       default    to-cpu enable TAC-class


Note: CPTP’s vFlow match criteria can be freely chosen to match the specific rate limiting need of the user provided they include a to-cpu or copy-to-cpu action for packets.


After issue resolution, the user can delete a previously created custom CPU class if no longer needed:


CLI (network-admin@switch) > cpu-class-delete


name

Specify the name of the CPU class to delete.

                                             

                                         

Or you can modify the CPU class after creating it:


CLI (network-admin@switch) > cpu-class-modify


name

Specify the name of the CPU class.

rate-limit rate-limit-number

Specify the cap for the rate limit.

hog-protect disable|enable|enable-and-drop

Specify if you want to enable, enable and drop packets, or disable hog protection.



Note: You cannot modify the scope of the CPU class. If you want to change the scope, you must delete the existing CPU class and create a new CPU class with the correct scope.


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