This article addresses a connectivity issue between Juniper EX4650 and EX2300 switches where the link remains down due to auto-negotiation incompatibility when using 1-gigabit fiber SFP transceivers on the EX4650.
>Port ge-0/0/36 on EX4650 is up, but the remote port ge-0/1/0 on EX2300 remains down.
>Auto-negotiation is enabled on the EX2300 interface.
>Auto-negotiation is not listed in the extensive interface output for the EX4650
As per Juniper documentation: https://www.juniper.net/documentation/us/en/hardware/ex4650/topics/topic-map/ex4650-hardware-overview.html
"EX4650-48Y does not support autonegotiation when 1-gigabit fiber SFP transceiver is plugged in. In such cases, it is recommended to disable auto-negotiation on the remote end device"
To resolve this, auto-negotiation must be disabled on the remote end device (EX2300).
set interfaces ge-0/1/0 speed 1g set interfaces ge-0/1/0 link-mode full-duplex set interfaces ge-0/1/0 ether-options no-auto-negotiation
- In the following image, interface ge-0/1/0 is up because Auto-negotiation is Disabled