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Pause frames not being passed

Posted: Sat Feb 27, 2016 1:01 pm
by STBAZ
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Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 2:05 pm
by sirhc
Explain why you think they are not being passed?

Remember this is how it works:

Say you have an AP on port 4 and your router on port 1

Say too much data is being sent from the router into port 1 destined to port 4 for the AP, if the AP can not send the data out across the wireless link as fast as it gets it the buffers on port 4 will fill up so at this point the switch will issue a Tx Pause Frame on Port 1 to the router.

So you will see a Tx Pause Frame on Port 1 because the the buffers on port 4 were full, you will not see any Pause frames on Port 4.

If for some reason your switch is sending too much data out port 1 to your router and the router port buffer fills up then you will see an Rx Pause frame on port 1 which was a Tx Pause frame from the router.

I have tested the crap out of this and it works as intended. We do not write the switch core code this is built into the core and this core in a 5 year old mature product so trust me the core features of the switch are correct.

All we do is write the interface that configures the core.

Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 2:06 pm
by ste
2 possibilities

1. Buffering of the switch handled this
2. Negotiating flow control did not work

Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 4:13 pm
by STBAZ
Chris so you’re saying these are upload pause frames?

I’m using edgemax for my routers, I’m about to switch to a few cisco's I have lying around for flow control.

STE can you elaborate on you hypothesis please, ie how to test it and what to do about it?

Thanks

Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 4:16 pm
by STBAZ
right now we run off a 150 by 20mbps circuit.
this coming week we are adding 200mbps Symmetrical so if these are upload pause frames that should go away.
How ever when we are flowing 140mbps out we only flow 5 to 10 in. yes I know im too low on bandwidth, it took a while to find a 2nd supplier we could afford.

Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 4:35 pm
by sirhc
STBAZ wrote:Chris so you’re saying these are upload pause frames?

I’m using edgemax for my routers, I’m about to switch to a few cisco's I have lying around for flow control.


Whatever is connected to Port 1 sent 412,620 Tx Pause Frames to Port 1 telling it to pause for 50 microseconds.

Port 1 is reporting it received 412,620 Rx Pause Frames.

Port 1 was told to hold up for 50 microseconds on 412,620 occurrences which would indicate that traffic was leaving port 1 faster than the device could handle it due to some circumstances in that direction, possibly further out in that direction if everything in that direction has FC.

I was told UBNT was going to get FC working on the EdgeMAX Routers?

Re: Pause frames not being passed

Posted: Sat Feb 27, 2016 8:39 pm
by STBAZ
ubnt snuck flow control by me
thanks Chris