Bad UDP checksum for flows - v2.57

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JS

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Jun 26, 2019, 9:38:16 AM6/26/19
to TRex Traffic Generator
Hi,
I am seeing an issue with my TREX setup where I am noticing bad UDP checksum for my flows. I am using Trex v2.57, GUI v4.5.5, mellanox CX5 running OFED 4.6-1.0.1 on centos 7.6.



As for traffic profile, I am using a dot1q tagged UDP flow with 100k users. Default options for UDP.


2019-06-26 13:20:57.373481 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.157.65.1021 > 2.2.158.65.1023: [bad udp cksum 0xae10 -> 0xae18!] UDP, length 1442
2019-06-26 13:20:57.373485 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.157.65.1021 > 2.2.158.65.1023: [bad udp cksum 0xae10 -> 0xae18!] UDP, length 1442
2019-06-26 13:20:57.373488 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.40.17.1021 > 2.2.41.17.1023: [bad udp cksum 0x9871 -> 0x9879!] UDP, length 1442
2019-06-26 13:20:57.373491 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.118.49.1021 > 2.2.119.49.1023: [bad udp cksum 0xfc30 -> 0xfc38!] UDP, length 1442
2019-06-26 13:20:57.373493 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.40.17.1021 > 2.2.41.17.1023: [bad udp cksum 0x9871 -> 0x9879!] UDP, length 1442
2019-06-26 13:20:57.373496 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.118.49.1021 > 2.2.119.49.1023: [bad udp cksum 0xfc30 -> 0xfc38!] UDP, length 1442
2019-06-26 13:20:57.373499 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.40.17.1021 > 2.2.41.17.1023: [bad udp cksum 0x9871 -> 0x9879!] UDP, length 1442
2019-06-26 13:20:57.377381 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.79.33.1021 > 2.2.80.33.1023: [bad udp cksum 0x4a51 -> 0x4a59!] UDP, length 1442
2019-06-26 13:20:57.377391 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.157.65.1021 > 2.2.158.65.1023: [bad udp cksum 0xae10 -> 0xae18!] UDP, length 1442
2019-06-26 13:20:57.377395 3a:44:64:56:f7:24 > ca:49:3c:28:f5:22, ethertype 802.1Q (0x8100), length 1496: vlan 103, p 0, ethertype IPv4, (tos 0x0, ttl 127, id 1234, offset 0, flags [none], proto UDP (17), length 1478)
    1.1.79.33.1021 > 2.2.80.33.1023: [bad udp cksum 0x4a51 -> 0x4a59!] UDP, length 1442

hanoh haim

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Jun 26, 2019, 9:57:14 AM6/26/19
to JS, TRex Traffic Generator
Please share the profile json?

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JS

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Jun 27, 2019, 9:29:37 AM6/27/19
to TRex Traffic Generator
Hi Hanoch,
Attached is the traffic profile. Thanks.
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test1.json

hanoh haim

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Jun 27, 2019, 9:39:58 AM6/27/19
to JS, TRex Traffic Generator
Could you verify without dot1q? There might be a CX-5 limitation using the hardware checksum. 
Another workaround is to use software mode (IPv4 header) and set the UDP checksum to be zero 

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Jimit Salvi

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Jun 27, 2019, 9:47:47 AM6/27/19
to hanoh haim, TRex Traffic Generator
I see the checksum is correct for TCP flows.

Sorry I am not familiar with software mode?

hanoh haim

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Jun 27, 2019, 10:01:25 AM6/27/19
to Jimit Salvi, TRex Traffic Generator
just set the UDP.cs=0 and use this instruction to fix IPv4 header 

 

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