ARP packet storm with AM335x

Sophia Kalibo

Intellectual 490 points

Hi,

I have 2 am335x devices on hand, each one has 2 LAN port. (as the following figure)

Network topology:

LAN 1

Device A <-----------------> Device B
Device A LAN 2 : loopback jig
Device B LAN 2 : loopback jig

I find that It will cause ARP strom to destroy the operation of local network only if the loopback jig is plugged before booting up.

But if I wait the booting progress finished and plug the loopback jig, there is no any abnormal situation!

Is this a CPU limitation ?

OS: Linux AM335xPSP_04.06.00.11

Thanks for any advice.

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

How are the CPSW's configured? What is the purpose of these loopbacks?

0 Miroslav Kiradzhiyski XID over 12 years ago

TI__Mastermind 25235 points

Hi Sophia,

I'm not sure about loopback mode, but if the kernel doesn't detect any connection on the PHY during boot, it will not bring up the corresponding ETH interface.

If the connection is made later, at runtime, then you need to bring up the interface:

root@am335x-evm:~# ifup eth0

Best regards,
Miroslav

0 Sophia Kalibo over 12 years ago in reply to Biser Gatchev-XID

Intellectual 490 points

Hi Biser,

How are the CPSW's configured

=> I'm not sure what do you mean, please refer to the attached file cpsw.c

What is the purpose of these loopbacks

=> For hardware test.

Thank you!

5047.cpsw.c

0 Sophia Kalibo over 12 years ago in reply to Miroslav Kiradzhiyski XID

Intellectual 490 points

Hi Miroslav,

Thank you for reply.

The ethernet interface are already enabled.

But ARP storm will happen when loopback kit is plugged before booting device up.

When I unplugged the loopback kit, the ARP storm is stopped, even thought plugged the loopback kit back.

My guess is:

=> Something is wrong in network initialization with loopback kit during booting up stage.

0 Sophia Kalibo over 12 years ago in reply to Sophia Kalibo

Intellectual 490 points

This issue is solved.

I modified the slave_reg_ofs in device.c

Thank you all

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ARP packet storm with AM335x