[c-nsp] "speed nonegotiate" command under optical transceiver configuration

[Martin T]

I found a good document describing "speed nonegotiate" command:
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/intrface.html#wp1040549

First of all, the name of the command seems to be as misleading as
possible :) It does not negotiate port speed. It should be "link
nonegotiate" or something similar. Looks like it's available only in
case of optical ports and sent information is flow-control parameters,
remote fault information and duplex information.

As I understand, those checks are implemented on Cisco gear only. For
example if I set "speed nonegotiate" on port Gi2/2 on switch port(in
other words it operates as non-Cisco optical port):

!
interface GigabitEthernet2/2
 speed nonegotiate
end


..and port Gi4/1 has default configuration:

!
interface GigabitEthernet4/1
end

..then port Gi2/2 is "connected" while Gi4/1 is "notconnect" which
makes sense as Gi2/2 is not expecting information negotiated during
link negotiation.


regards,
Martin


2013/2/8, Martin T <m4rtntns at gmail.com>:
> 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
>