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Why did my command not take?

lbuckner1
Level 1
Level 1

So back in late March, I setup a 24 port switch to replace a 48 port switch.  The fiber connection I replicated on gi1/1/4.  Here is the putty log of when I did this, saving just after:

P_Mount_3560G_SW1(config)#int gi1/1/4
FP_Mount_3560G_SW1(config-if)#spp eed ne
FP_Mount_3560G_SW1(config-if)#speed nego
FP_Mount_3560G_SW1(config-if)#speed nego ?
% Unrecognized command
FP_Mount_3560G_SW1(config-if)#speed nego ?
10 Force 10 Mbps operation
100 Force 100 Mbps operation
1000 Force 1000 Mbps operation
auto Enable AUTO speed configuration
nonegotiate Do not negotiate speed

FP_Mount_3560G_SW1(config-if)#speed non
FP_Mount_3560G_SW1(config-if)#speed nonegotiate
FP_Mount_3560G_SW1(config-if)#exit
FP_Mount_3560G_SW1(config)#exit
FP_Mount_3560G_SW1#wr mem
Building configuration...
Compressed configuration from 3894 bytes to 1931 bytes[OK]

The last thing I did was do a "show running-config" and it spit it out, and shows that that command is _not_ there on that port.

interface GigabitEthernet1/1/2
switchport mode trunk
!
interface GigabitEthernet1/1/3
switchport mode trunk
!
interface GigabitEthernet1/1/4
switchport mode trunk
!
interface Vlan1
no ip address
ip helper-address 10.168.40.198
shutdown
!

I glossed over the fact that IT ISN'T THERE!!!

I'm sitting at a bar right now with my supervisor.  The field tech says it isn't working.  Long story/short: supervisor dials in, sets the speed on 1/1/1 and asks why I didn't.  Luckily, I had my putty log to show him.

What the heck?  Can someone explain this mystery?

6 Replies 6

Leo Laohoo
Hall of Fame
Hall of Fame

What kind of port are we talking about?  Copper or Fibre Optic?

Fiber

Fiber

Fibre only has one speed and always full duplex.  Trying to manually configure speed and/or duplex settings will always result in an error message.

If someone was able to configure either speed or duplex (or both) settings and the link went down, then the "ability" is a bug in itself.

If we don't set the fiber port to "speed nonegotiate" then It doesn't work. 

So this whole time we have been configuring a bug?

So this whole time we have been configuring a bug?

Maybe I'm getting ahead of myself.  So what router/switch model is this happening and what is the firmware it's running on?

The only time one can configure the speed and/or duplex settings on an SFP port is when the SFP module is a GLC-T/GLC-TX.

While it's true what Leo says - you cannot change the speed of a fiber SFP transceiver - I have seen interoperability issues with upstream 3rd party SFPs (talking about you Juniper) where if one does not hard code it - either with nonegotiate or setting the speed confirming the hardware setting - the link will not come up.