How to generate PAUSE frame

[bill]

At 2011-07-22 01:27:14,"Jeff Haran" <jharan at bytemobile.com> wrote:
>> -----Original Message-----
>> From: kernelnewbies-bounces at kernelnewbies.org [mailto:kernelnewbies-
>> bounces at kernelnewbies.org] On Behalf Of bill
>> Sent: Wednesday, July 20, 2011 11:11 PM
>> To: kernelnewbies
>> Subject: How to generate PAUSE frame
>> 
>> Hi, all
>> 
>> 
>> I have a 10G NIC card with fiber interface, this NIC is drived by a
>private os
>> with l2 rxonly forwarding function,
>> and I want to test this NIC could sent out PAUSE frame.
>> 
>>   host                       client
>> +--------+                +------------+
>> |            |    fiber       |  10G NIC |
>> |  NIC    |  <===>   |  l2fwd      |
>> |            |                 |  rxonly     |
>> +--------+                +------------+
>> 
>> If host send packet faster than client could receive, client 10G NIC
>should
>> send out PAUSE frame,
>> and use "ethtool -a eth0" on host to show any PAUSE frame received.
>> 
>> How could I do this without any faster NIC card than 10G?
>> 
>> 
>> 
>> thanks
>> 
>> bill
>
>I think you are going to have a hard time finding any host in the form
>of a general purpose computer that can saturate a 10G link.
>
>You probably want to look into commercial frame generators from
>companies like Smartbits or Ixia. They have special hardware for doing
>this kind of thing. These solutions aren't cheap though.
>
>You *MIGHT* be able to do this if you replaced host with the right 10G
>switch. I am thinking if you turned off spanning tree and then looped a
>fiber from one of the switch ports back to another one, and then caused
>a broadcast frame (say an ARP request) to be injected into a third
>switch port, you might be able to cause a broadcast storm which would
>hit client's interface and that might be a high enough packet rate to
>make it generate a pause. The question then would be if the switch has
>the right software to report whether it received a pause from client.
>And I really don't know if this solution would be cheaper than getting
>one of the frame generators.
>
>Jeff Haran
>

Thanks Jeff
 I'll try to use two 10NIC cross connected to each other, see whether this way could generate PAUSE frame.

bill


>
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