TDA4VM: CPSW2G: IEEE length error drop

Hi,

Hasan Aarzoo said:

On CPSW2G, I can see the above mentioned statistics keeps on increasing if CPSW2G receives Ethernet frames with invalid length. But the Ethernet frame is not dropped and is reecived in the memory buffers allocated for reception.

Can you please share more details about the length of frames received?

Are those above 33 bytes or below?

Also, check if RX_CSF_EN is enabled in the MAC Ports?

Best Regards,
Sudheer

Hi Sudheer,

Doredla Sudheer Kumar said:

Can you please share more details about the length of frames received?

Please have a look at the ethernet frame which I was using:


Here, I put invalid Ethertype so that it be classified as invalid frame. As mentioned above, I can see the CPSW_STAT1_ALE_LEN_ERROR_DROP increasing but the frame was received in the OCRAM space allocated for reception.

Doredla Sudheer Kumar said:

Are those above 33 bytes or below?

Bigger than 33 bytes

Doredla Sudheer Kumar said:

Also, check if RX_CSF_EN is enabled in the MAC Ports?

It is disabled.

Open questions:

1. Is it possible to drop Ethernet frame which are counted by CPSW_STAT1_ALE_LEN_ERROR_DROP?If yes, how?

Looking forward to hearing back from you.

Best regards,
Hasan

Hi,

Hasan Aarzoo said:

Is it possible to drop Ethernet frame which are counted by CPSW_STAT1_ALE_LEN_ERROR_DROP?If yes, how?

Please check whether the below is enabled or not in your case.


The above will drop all error frames due to BAD Length as per IEEE 802.3.

Best Regards,
Sudheer

Hi Sudheer,

I have this bit enabled but still the frames are not dropped.



The frames I am sending with CANoe are in statistics of MAC PORT are marked as ALE_LEN_ERROR_DROP.

But also reffered as RX_GOOD_FRAMES


and at the end received in the OCRAM allocated for reception of ethernet packets.



The ethernet packet shown below is transmiited from CANoe to CPSW2G:


Even if I use Length/Type (2 bytes): 0x00, the same behiviou explained above is observed.

Looking forward to hearing back from you.

Best regards,
Hasan

Hi,

Hasan Aarzoo said:

The ethernet packet shown below is transmiited from CANoe to CPSW2G:

I could see that the payload length is 1500.

Have you tried sending more than 15000 bytes? If not, can you please check.

Best Regards,
Sudheer

Hi Sudheer,

Hasan Aarzoo said:

Even if I use Length/Type (2 bytes): 0x00, the same behiviou explained above is observed.

Same behaviour observed if I set the Length to 0 and send ethernet packet of size 1500 bytes.

Doredla Sudheer Kumar said:

Have you tried sending more than 15000 bytes? If not, can you please check.

In this case, based on my cps2g configuration, it will be dropped as an oversized frame.


I want ALE to drop all ethernet packets which don't comply with length specified in ethernet packet.

Imagine the following simplified Ethernet 802.3 frame structure:

Error: Length field = 32 bytes, but actual payload = 100 bytes

I want to drop these frames.

Looking forward to hearing back from you.


Best regards,
Hasan

Hi,

As per the description, it will drop when the length field is larger than the packet size.

Hasan Aarzoo said:

Field	Value
Destination MAC	AA:BB:CC:DD:EE:FF
Source MAC	11:22:33:44:55:66
Length field	0x0020 (32 bytes)
Payload (actual)	100 bytes
FCS	CRC checksum

Error: Length field = 32 bytes, but actual payload = 100 bytes

You can try to length of 200 and an actual payload of 100 bytes.

Best Regards,
Sudheer

Hi Sudheer,

Doredla Sudheer Kumar said:

You can try to length of 200 and an actual payload of 100 bytes.

Yes, it is working. But why ALE_IEEE_LEN_ERR drop statistics is counted for frames when Length fiels is smaller than actual Payload size in an ethernet frame?

Looking forward to hearing back from you.

Best regards,
Hasan 

Hi,

Hasan Aarzoo said:

Doredla Sudheer Kumar said:

You can try to length of 200 and an actual payload of 100 bytes.

Yes, it is working. But why ALE_IEEE_LEN_ERR drop statistics is counted for frames when Length fiels is smaller than actual Payload size in an ethernet frame?

When I am sending, Length filed is smaller than or equal to payload size, I haven't seen ALE_IEEE_LEN_ERR drop statistics incrementing.
Please refer to the below Log, statistics captured before and after receiving an 802.3 frame with length field 0.



Can you please re-check on your side? 


Best Regards,
Sudheer

Hi Sudheer,

The ethernet frame used by you  contains length field as 0x8100 not 0x0 may be a misconfiguration.


I am sure you will observe the same behaviour as I am observing by setting it to 0x0 instead of 0x8100.

Doredla Sudheer Kumar said:

Can you please re-check on your side? 

I have rechecked it and the behaviour is still same.


Looking forward to hearing back from you.

Best regards,
Hasan

Hi,

Hasan Aarzoo said:

The ethernet frame used by you  contains length field as 0x8100 not 0x0 may be a misconfiguration.


I am sure you will observe the same behaviour as I am observing by setting it to 0x0 instead of 0x8100.

In my system, by default, VLAN is enabled, and the packet is tagged with VLAN ID 0.

Hasan Aarzoo said:

Doredla Sudheer Kumar said:

Can you please re-check on your side? 

I have rechecked it and the behaviour is still same.

Let me check by removing the VLAN once.

Best Regards,
Sudheer

Hi Sudheer,

Please let me know when you have an update on this ticket.

Best regards,
Hasan

Hi,

Doredla Sudheer Kumar said:

Hasan Aarzoo said:

Doredla Sudheer Kumar said:

Can you please re-check on your side? 

I have rechecked it and the behaviour is still same.

Let me check by removing the VLAN once.

I have tested by disabling VLAN-aware mode, and the observation is still the same.
Please refer to the logs below for your reference.


Best Regards,
Sudheer

Hi Sudheer,

I have these additional settings for ALE Length error drop statistics:

• CPSW_ALE_STAT_DIAG;PORT_DIAG = 1
• CPSW_ALE_STAT_DIAG;STAT_DIAG =5
  
  

How these ALE statistics are different from ALE statistics provided by STATS module?

Best regards,
Hasan

Hi Sudheer,

Thank you for the information and efforts.

Best regards,
Hasan