cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
yhm
Adventurer
Adventurer
6,610 Views
Registered: ‎09-10-2013

The packet loss of GTX transceiver

Jump to solution

Hi  , all

 

In my last forum post. I mentioned the packet loss rate of GTX transceiver (Kintex 7).

 

Here, I do a durther explanation.

 

1,  board : ACDC 1.0  (XC7K325T)

2,  SoftWare : ISE 14.7

3,  GTX version: 2.7

     3.1  GTX line rate : 1.25Gbps

     3.2  protocol: GE no CC

     3.3  8b/10b   K28.5

     3.4  The two GTs' reference clock is the same

     3.5  The design use the example design just delete frame generator and frame check, The input signal “GT_DATA_VALID_IN” is set to high.

 

4,   Test block diagram

 

绘图1.jpg

 

5, The test result shows the communications between PCs always exists packet loss rate (about 10^(-3)).

 

6, The further test shows the receiver of GT receive error bits when the packet loss, even though the “resetdone” is high and “byte alignment” is not lost.

 

7, I guess that the GT is not configured well.

 

Anyone encountered this problem?

 

Thanks!

Regards!

yhm

0 Kudos
1 Solution

Accepted Solutions
mcgett
Xilinx Employee
Xilinx Employee
10,634 Views
Registered: ‎01-03-2008

> 3.2  protocol: GE no CC

> 3.4  The two GTs' reference clock is the same

 

Gigabit Ethernet requires the use of clock correction to handle the PPM difference between the source and the destination.  The Source PC is operating at 1250 Gbps +/-XX ppm while the receiver on your FPGA is operating at 1250Gbps +/-YYppm.  The only way for a 0 PPM difference to be achieved is if the both transmitter and reciever is operating off of the same clock source which is impossible to achieve in your configuration.

 

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com

View solution in original post

0 Kudos
4 Replies
venkata
Moderator
Moderator
6,343 Views
Registered: ‎02-16-2010
How is the data transferred from GT0 to GT1 and vice-versa? Can you sample the data inside the FPGA to confirm the direction in which the packet loss is happening?
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
yhm
Adventurer
Adventurer
6,333 Views
Registered: ‎09-10-2013

Thanks,venkata

 

>>How is the data transferred from GT0 to GT1 and vice-versa?

 

"GT0_RXDATA_OUT"            ------>   "GT1_TXDATA_IN"

"GT0_RXCHARISK_OUT"     ------>  "GT1_TXCHARISK_IN"

 

"GT1_RXDATA_OUT"            ------>   "GT0_TXDATA_IN"

"GT1_RXCHARISK_OUT"     ------>   "GT0_TXCHARISK_IN"

 

>>Can you sample the data inside the FPGA to confirm the direction in which the packet loss is happening?

 

The packet loss is always happened in two directions (GT0->GT1 and GT1->GT0)

 

Thanks again

 

Regards

yhm

0 Kudos
venkata
Moderator
Moderator
6,299 Views
Registered: ‎02-16-2010
Try to make a loopback connection at the SFP connector in FM-S14 and confirm the link using IBERT.

If possible, use a RJ45 loopback connector after the media converter also do the same test as above.
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
0 Kudos
mcgett
Xilinx Employee
Xilinx Employee
10,635 Views
Registered: ‎01-03-2008

> 3.2  protocol: GE no CC

> 3.4  The two GTs' reference clock is the same

 

Gigabit Ethernet requires the use of clock correction to handle the PPM difference between the source and the destination.  The Source PC is operating at 1250 Gbps +/-XX ppm while the receiver on your FPGA is operating at 1250Gbps +/-YYppm.  The only way for a 0 PPM difference to be achieved is if the both transmitter and reciever is operating off of the same clock source which is impossible to achieve in your configuration.

 

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com

View solution in original post

0 Kudos