Symptom

individual 25G breakout lane(s) do(es) not link up after performing no shut/admin up 100G breakout 25Gb lane 1/20/2 ------------------------ NIC N9K-C9336C-FX2-1# sh int br | in 1/20 Eth1/20/1 -- eth routed down Administratively down auto(D) -- Eth1/20/2 -- eth routed down Link not connected auto(D) -- << remains not connected Eth1/20/3 -- eth routed down Administratively down auto(D) -- Eth1/20/4 -- eth routed down Administratively down auto(D) --

Conditions

1. Cloudscale N9K platform 2. 100G QSFP used in 100G port configured in 4x25G breakout mode example: 9K# show run | in breakout interface breakout module 1 port 20 map 25g-4x 9K# sh int transceiver | in ^Eth|name|type | in INN p 2 Ethernet1/20/1 type is QSFP-100G-SR4-S << 100G broken into 4x 25G 1/20/1-4 name is CISCO-INNOLIGHT Ethernet1/20/2 type is QSFP-100G-SR4-S name is CISCO-INNOLIGHT Ethernet1/20/3 type is QSFP-100G-SR4-S name is CISCO-INNOLIGHT Ethernet1/20/4 type is QSFP-100G-SR4-S name is CISCO-INNOLIGHT 513E.C.14-N9K-C9336C-FX2-1# 3. Not all 4x 25G lanes are in use. Among the lanes that are not in use, at least one is configured admin down.

Workaround

admin up all 4x 25Gbps breakout lanes and in some cases connect physical links and bring up all the other links: consider 100G port with breakout cable, broken up into 4x 25G ports e X/Y/1-4 conf t ; interface eX/Y/1-4 ; no shut

Further Problem Description