We have a problem at the configuration between ASR router and FEX switch, both joined with SFP fiber. We need to hard-coded the interface to 1G. A new equipment will be inserted between them and it's mandatory to fix interface to 1GB.
At switch side we may hard-coded to 1000 and no negotitate auto, but at router side there is only the possibility of no negotiation auto. Router has GLC-LH-SMD and 1G interface (so, no more options are available).
With no negotiation auto command, the link is up but there are no ping between devices. If it's changed to negotiation auto, the link is up and the ping between devices are recovered.
May you help us to understand why this behaviour? How to hard-code the interfaces and have a correct operation?
@mtotelenivel1 wrote: We have a problem at the configuration between ASR router and FEX switch, both joined with SFP fiber. We need to hard-coded the interface to 1G. A new equipment will be inserted between them and it's mandatory to fix interface to 1GB.
There is no need to do that because the optics can only work at one speed only. If the optics is SFP that then it always work on 1 Gbps, full duplex.
Thank you @marce1000, @Leo Laohoo . Before adding a new device (Allot) between router and switch we try to test what is mandatory by Allot, hard-code interfaces. The only way to avoid negotitation is with no negotiation auto command and there is a problem in the communication between Cisco devices. With allot device in the middle was also tested and the link was down. So we tried only with Cisco devices that work properly in autonegotiation, but don't work in no negotiation auto. Without Allot there wont be any problem, we let the interfaces in auto, but this is not what Allot requires.