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port speed wont negotiate

hello,

i have moved a server from a 3750 switch to a 3850 switch.  it only auto negotiates to 100mb full.  i want it to negotiate to 1000mb like the rest of my servers which are all 1gb.

 

here is the config

switchport mode access

switchport nonegotiate

spanning-tree portfast

 

i also tried

speed 1000

duplex full

 

but it wont negotiate. 

is their anything that i am missing or do i need the server guy to take a look at the NIC on the server

 

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: port speed wont negotiate

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,

 

2 REPLIES 2
Cisco Employee

Re: port speed wont negotiate

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,

 

Highlighted
Participant

Re: port speed wont negotiate

Turns out i had a faulty cable. As soon as i replaced it the port came up as 1GB
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