Symptom
- Control-plane / data traffic not sent out of affected ports. This may cause issues such as:
- peer devices not getting CDP/LLDP traffic from affected switch.
- UDLD err-disable due to UDLD frame not being sent.
- MAC flaps due to STP port going unblocking due to STP BPDU not being sent.
- LACP member ports going to suspended due to LACP PDU not being sent.
- Error message when modifying affected port QoS config: " %FED_QOS_ERRMSG-3-QUEUE_BUFFER_HW_ERROR: Switch 1 R0/0: fed: Failed to configure queue buffers for TenGigabitEthernetx/y/z: code 1."
- Affected Ports increment output drops.
- Egress queue buffers stuck, even when affected port is admin down.
- Check for output drops on affected interface. Check for non-zero "queue buffers" count for queue 0 and 1, even when affected port is admin down.
c3850#show platform hardware fed switch 1 qos queue stats interface t1/0/7
DATA Port:6 Enqueue Counters
-----------------------------------------------------------------
Queue Buffers Enqueue-TH0 Enqueue-TH1 Enqueue-TH2 Qpolicer
(Count) (Bytes) (Bytes) (Bytes) (Bytes)
----- ------- ------------ ------------ ------------ ------------
0 2500 0 998532 97822 0
1 1474 0 0 12058431 0
^^^^^^^ non-zero count
DATA Port:6 Drop Counters
-----------------------------------------------------------------------------------
Queue Drop-TH0 Drop-TH1 Drop-TH2 SBufDrop QebDrop QpolicerDrop
(Bytes) (Bytes) (Bytes) (Bytes) (Bytes) (Bytes)
----- ------------ ------------ ------------ ------------ ------------ ------------
0 0 129768 545951 0 0 0
1 0 0 0 0 0 0
^^^^^^ Output drops in queue 0 (control-plane)
Conditions
- Affected models are WS-C3850-48XS and WS-C3650-12X48UZ. No other models affected
- 16.11.x and 16.12.x affected. No other releases affected.
Workaround
Move affected links to different interface.
Further Problem Description
Only 3650/3850 platform with 40G fixed uplink is impacted by this bug. Catalyst 9k not affected.
