Cannot link a Catalyst 9300 10G SFP+ port to a Catalyst 4503-E 1G SFP port
4
The poster's newly acquired Cisco Catalyst 9300 (with an 8-port 10G SFP+ network module) would not link to a Cisco Catalyst 4503-E that only has 1G SFP ports. Suspecting a 10G-versus-1G speed mismatch, the poster tried to force the 9300's 10G SFP to operate at 1G with the 'speed' command, but the command is not accepted on SFP interfaces. The question was whether a 10G optic can be made to run at 1G so that it can talk to the 1G SFP on the 4503-E.
- Hardware: Cisco Catalyst 9300 with 8-port 10G SFP+ network module, Cisco Catalyst 4503-E
- Transceivers: unspecified 10G SFP+, unspecified 1G SFP
- Form factor: SFP+, SFP
Symptoms / messages:
no link between 10G SFP+ port and 1G SFP port
speed command rejected on SFP interface
10G vs 1G speed mismatch
Comments 3
Accepted: no, an SFP's speed is fixed by the module type; a 10G optic cannot be forced to 1G.
Accepted: there is no auto-negotiation on fiber, so both ends must use the same kind of SFP at the same speed, and the modules must be supported by each device.
A respondent added that many 10G ports are actually SFP+ ports that accept either a 1G or a 10G SFP, so a 1G SFP in the 9300 module (if the module supports it) can match the 4503-E, with the optics also matched for media (SX to SX, LX to LX).