Hi, one can apply "speed nonegotiate" command under interface configuration mode in case of optical SFP/GBIC. Looks like this command is supported only in case of optical transceivers. For example I have a Cisco WS-C3750G-12S switch and if I insert copper SFP to port Gi1/0/2, I do not have "speed nonegotiate" command available:
C3750(config-if)#do sh int Gi1/0/2 status Port Name Status Vlan Duplex Speed Type Gi1/0/2 notconnect 1 auto auto 10/100/1000BaseTX SFP C3750(config-if)#speed ? 10 Force 10 Mbps operation 100 Force 100 Mbps operation 1000 Force 1000 Mbps operation auto Enable AUTO speed configuration C3750(config-if)#speed Now if I remove the copper SFP and insert optical SFP or do not insert nothing at all, I have "speed nonegotiate" command available: C3750(config-if)#do sh int Gi1/0/2 status Port Name Status Vlan Duplex Speed Type Gi1/0/2 notconnect 1 auto auto 1000BaseLX SFP C3750(config-if)#speed ? nonegotiate Do not negotiate speed C3750(config-if)#speed In addition, I have one one optical SFP with modified EEPROM so that it appears as an copper SFP to the switch and thus "speed nonegotate" command is not available: C3750(config-if)#do sh int Gi1/0/2 status Port Name Status Vlan Duplex Speed Type Gi1/0/2 notconnect 1 auto auto 10/100/1000BaseTX SFP C3750(config-if)#speed ? 10 Force 10 Mbps operation 100 Force 100 Mbps operation 1000 Force 1000 Mbps operation auto Enable AUTO speed configuration C3750(config-if)#speed Same behavior can be seen on Cisco 4500 platform where optical GBIC's(on WS-X4306-GB module) support "speed nonegotiate" command and copper GBIC's(WS-G5483) do not. 1000BASE-SX or 1000BASE-LX10 support only 1GigE mode so there should be nothing to negotiate in terms of speed.. In practice, I have used "speed nonegotiate" command in case I connect Cisco optical SFP to a media-converter and I have heard that connecting optical transceivers to non-Cisco gear (sometimes) require "speed nonegotiate" command. Otherwise link will not come up. Am I correct, that "speed nonegotiate" is available only on optical transceivers? What is the history behind "speed nonegotiate" command? What information is exchanged and expected by Cisco device if "speed nonegotiate" command is not applied? regards, Martin _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
