This article explains the reason for message syslog of "Failed to disable PCA9548(0x70)->channel(0-7)" and how to clear the error.

The similar error messages might be observed on MPC card as below:

Jul 2 15:25:56 2024 router : %PFE-3: fpc6 PQ3_IIC(WR): bus transfer timeout on byte 0

Jul 2 15:25:56 2024 router : %PFE-3: fpc6 PQ3_IIC(WR): transfer not complete on byte 0

Jul 2 15:25:56 2024 router : %PFE-3: fpc6 PQ3_IIC(WR): I/O error (i2c_stat=0x20, i2c_ctl[0]=0xb0, bus_addr=0x70)

Jul 2 15:25:56 2024 router : %PFE-3: fpc6 Failed to disable PCA9548(0x70)->channel(0-7)

This issue was addressed in PR1374450.

The root cause is that, the time to wait for the i2c transaction is not sufficient to finish the i2c transaction intermediately, hence once in a while we can see this i2c transaction error. These errors don't impact any functionality on the card.

Starting from following junos, the timeout for i2c transaction is increased to fix the error.

17.3R3-S3 17.3R4 17.4R2-S2 17.4R3 18.1R3-S2 18.1R4 18.2R2 8.2X75-D20 18.3R1 18.3R2 18.4R1 19.1R1