Hello Ohareka70,
Please find below some guidelines for Cisco Catalyst 3850:
Speed and Duplex Configuration Guidelines
When configuring an interface speed and duplex mode, note these guidelines:
- The 10-Gigabit Ethernet ports do not support the speed and duplex features. These ports operate only at 10,000 Mb/s and in full-duplex mode.
- Gigabit Ethernet (10/100/1000-Mb/s) ports support all speed options and all duplex options (auto, half, and full). However, Gigabit Ethernet ports operating at 1000 Mb/s do not support half-duplex mode.
- For SFP module ports, the speed and duplex CLI options change depending on the SFP module type:
- The 1000BASE-x (where -x is -BX, -CWDM, -LX, -SX, and -ZX) SFP module ports support the nonegotiate keyword in the speed interface configuration command. Duplex options are not supported.
- The 1000BASE-T SFP module ports support the same speed and duplex options as the 10/100/1000-Mb/s ports.
For information about which SFP modules are supported on your switch, see the product release notes.
- If both ends of the line support autonegotiation, we highly recommend the default setting of auto negotiation.
- If one interface supports autonegotiation and the other end does not, configure duplex and speed on both interfaces; do not use the auto setting on the supported side.
- When STP is enabled and a port is reconfigured, the switch can take up to 30 seconds to check for loops. The port LED is amber while STP reconfigures.
For the interface on the Catalyst 3850 switch, please provide the following:
show interface GigabiEthernetX/Y/Z
show interface GigabiEthernetX/Y/Z capabilities
show interface GigabiEthernetX/Y/Z status
show idprom interface GigabiEthernetX/Y/Z
show inv | i X/Y/Z
Regards,
