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New Member

Multi vlan and Real time applications


I have one 2924M XL switch with two 100 Base FX ports installed. the two ports 100 BaseFX are configured as multi vlan port, and to these ports are connected two panel Pc Advantech.

On these panel Pc's are running applications real time, when I restart one of this panel Pc, It losses connection with some vlans configured in one of this ports 100 Base FX.

The 100Base Fx ports have the same configuration.

Could somebody tell me why is happening this?

Is there another manner for to do this without to use multi vlan ports?




Re: Multi vlan and Real time applications

I'm not exactly sure what you're seeing, based on your description.... but I'll take a couple shots...

If you see the link light go amber for ~one minute, then it is likely that you need to set the port to "portfast" which eliminates the spanning-tree checks for that port. It should ONLY be used if you know for a fact that only a PC will be attached to the port. the command for portfast is (from the "(config-int)#" prompt)

"spanning-tree portfast".

If the port comes up quickly, but you still lose some of the VLANs, it may be a driver issue on the PC side, or your 802.1q parameters may need to be adjusted.

If you are feeding several VLANs to a single interface on the PC, the switch port must be configured for "dot1q" trunks, and the PC interface must be set to use 802.1q protocol (creating several logical interfaces from a single physical interface).

Can you clarify your setup (and problem) a little more?


New Member

Re: Multi vlan and Real time applications

Hi Scott,

I have configured portfast for that port, and this port comes up quickly, but I still lose some of the Vlans.

I don't have configured 802.1q parameters on the switch or Pc, I have configured "Multi Vlan" parameters on the switch 2924M XL.

I don't know if the Pc interface support 802.1q parameters.

How can I validate it?

I think that it would be better to configure 802.1q parameters instead Multi Vlan parameters on the port of the switch