Exalt / RADWin FC

[mhoppes]

Recently it was brought to my attention that Exalt and RADWin microwaves do not support flow control on the Ethernet port.

Do the SAF microwaves? I'm guessing they since this is what you use Chris?

I'm looking into this because I'm seeing lots of dropped packets going into some RADWin and Exalt microwaves even though they were nowhere near capacity.

The network basically goes from:

50meg fiber ---> Cisco ---> airFiber ---> Cisco ---> RADWin/Exalt/etc ---> Devices with 1 and 2 megabits/second capacity.

Now along with that 50meg fiber is also a 300megabit/second Internet feed going across the same backbone.

Both RADWin and Exalt have told me that their radios do not support FC on the Ethernet interfaces.

My questions:
* Do the SAF radios support FC on the Ethernet interface or is it just a pass through?
* Does turning on FC do anything worthwhile if the switch is running out of buffer space, or is it only going to cause the entire network to syncronize and suffer?

[sirhc]

I would be surprised if any Ethernet 10/100 or 10/100/1000 device does not support Flow Control as it is a function of the Ethernet driver which I promise you Exault did not write. Now it is possible that the wireless side of the radio does not support Flow Control.

However Flow Control ONLY works if the device is set to Auto, if you hard set the speed or Duplex it disables Flow Control - Google Flow Control and read up on it.

The dropped packets can be for many reasons other than congestion or lack of Flow Control.

[mhoppes]

But in order to be used on the Ethernet side it has to be enabled by the software correct? So regardless if the feature is there or not I have no way to enable it.

Now, Exalt is telling me a FC packet should pass across their microwave -- but that doesn't sound right to me?

What other reasons would cause packet drops in your opinion? Those two are the only ones I've ever experienced it with.