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802.3x Flowcontrol on NAS Port(s)/LAG

Unanswered Question
Oct 11th, 2013
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Hi everyone,

on my network there are 4 Cisco SG300-10 switches connected to each other via a single uplink port. On one of these switches there is a LAG 802.3ad port configured that provides network access for a QNAP NAS. So far so good.

My problem is that I keep having connection issues with some Network Media players that don't support gigabit ethernet speed. These fast ethernet clients are connected to the mentioned switches and suffer from connection problems, "hickups" during video stream (via NFS-UDP). Now as this seems to be a known problem with my kind of setup I got the advice to configure the NAS ports (or the LAG in my case) to support 802.3x flowcontrol. But the advisors always assumed that the problematic fast ethernet clients were connected to the same switch as the NAS, but on my network this is not the case.

So my question is: Do I have to configure 802.3x Flowcontrol just on the NAS ports (LAG), or is it also necessary to configure it on the uplink ports between the switches and on the respective NMP ports in order to work as expected?

Thanks and best regards

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jeffrrod Fri, 10/18/2013 - 13:29
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Dear Christoph,

Thank you for reaching the Small Business Support Community.

It's been several days and nobody has answered/commented on your post and therefore I suggest you to inquire about these on a different support channel;


Thank you for your time and patience and please do not hesitate to reach me back if there is any further assistance I may help you with in the meantime.

Kind regards,

Jeffrey Rodriguez S. .:|:.:|:.
Cisco Customer Support Engineer

*Please rate the Post so other will know when an answer has been found.

Tom Watts Sat, 10/19/2013 - 06:35
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Hi Christophe, 802.3x has pause frames that it can send if there is a link over utilized. So you'd need to find out what is being over utilized. The switch or the NAS?

The purpose of the flow control is for the over utilized device to send the pause frame.

Please mark answered for helpful posts


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