Description

The init delay time specifies the number of seconds by which to delay bringing up the MC-LAG interface back to the up state when the MC-LAG peer is rebooted. By delaying the bring-up of the interface until after the protocol convergence, you can prevent packet loss during the recovery of failed links and devices.

With same init-delay-time value on multiple mc-ae interfaces, during booting up, MC-LAG peer tries to perform the following at the same time:

  • Bring up all mc-ae interfaces 
  • Establish LACP on all interfaces at the same time with peer access devices
  • Share all mc-ae interfaces info to MCLAG peer device.

Due to many operations being performed at the same time when a MC-LAG peer boots up, more CPU cycles are needed. Under this high CPU condition, there is possibility of a race condition like LACPD at Control Plane for all mc-ae interfaces might send CD to peer access device. However, TRUNK enable at PFE is still processing for some interfaces, which leads to traffic loss on mc-ae interfaces, and are not yet completely programed as TRUNK enable in PFE. Also, LACP establishment of mc-ae interfaces and sharing mc-ae interfaces status with peer MC-LAG devices using ICCP can be raced.

 

Solution

To avoid this, it is recommended to have a different value for each mc-ae interface in case of scaled setup.

Example:

set interfaces ae10 aggregated-ether-options mc-ae init-delay-time 240

set interfaces ae11 aggregated-ether-options mc-ae init-delay-time 245

set interfaces ae12 aggregated-ether-options mc-ae init-delay-time 250

set interfaces ae13 aggregated-ether-options mc-ae init-delay-time 255

set interfaces ae14 aggregated-ether-options mc-ae init-delay-time 260

set interfaces ae15 aggregated-ether-options mc-ae init-delay-time 265

set interfaces ae16 aggregated-ether-options mc-ae init-delay-time 270

set interfaces ae17 aggregated-ether-options mc-ae init-delay-time 275

set interfaces ae18 aggregated-ether-options mc-ae init-delay-time 280

set interfaces ae19 aggregated-ether-options mc-ae init-delay-time 285

set interfaces ae20 aggregated-ether-options mc-ae init-delay-time 290

set interfaces ae21 aggregated-ether-options mc-ae init-delay-time 295

set interfaces ae22 aggregated-ether-options mc-ae init-delay-time 300

set interfaces ae23 aggregated-ether-options mc-ae init-delay-time 305

set interfaces ae24 aggregated-ether-options mc-ae init-delay-time 310

set interfaces ae25 aggregated-ether-options mc-ae init-delay-time 315

set interfaces ae26 aggregated-ether-options mc-ae init-delay-time 320

set interfaces ae27 aggregated-ether-options mc-ae init-delay-time 325

set interfaces ae28 aggregated-ether-options mc-ae init-delay-time 330

set interfaces ae29 aggregated-ether-options mc-ae init-delay-time 335

set interfaces ae30 aggregated-ether-options mc-ae init-delay-time 340

set interfaces ae31 aggregated-ether-options mc-ae init-delay-time 345

set interfaces ae32 aggregated-ether-options mc-ae init-delay-time 350

set interfaces ae33 aggregated-ether-options mc-ae init-delay-time 355

set interfaces ae34 aggregated-ether-options mc-ae init-delay-time 360

set interfaces ae35 aggregated-ether-options mc-ae init-delay-time 365

set interfaces ae36 aggregated-ether-options mc-ae init-delay-time 370

set interfaces ae37 aggregated-ether-options mc-ae init-delay-time 375

set interfaces ae38 aggregated-ether-options mc-ae init-delay-time 380

set interfaces ae39 aggregated-ether-options mc-ae init-delay-time 385

set interfaces ae40 aggregated-ether-options mc-ae init-delay-time 390

set interfaces ae41 aggregated-ether-options mc-ae init-delay-time 395

set interfaces ae42 aggregated-ether-options mc-ae init-delay-time 400

set interfaces ae43 aggregated-ether-options mc-ae init-delay-time 405

set interfaces ae44 aggregated-ether-options mc-ae init-delay-time 410

set interfaces ae45 aggregated-ether-options mc-ae init-delay-time 415

set interfaces ae46 aggregated-ether-options mc-ae init-delay-time 420

set interfaces ae47 aggregated-ether-options mc-ae init-delay-time 425

set interfaces ae48 aggregated-ether-options mc-ae init-delay-time 430

set interfaces ae49 aggregated-ether-options mc-ae init-delay-time 435

 

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