Thanks, that helped a lot. I found that traffic is not passing through the
node as I expected it.
The actual graph is
tcp4-output -> ip4-lookup -> ip4-rewrite -> upf-if-input
Note: upf-if-input is the node function of an interface. It is found
through a fib entry that look like this:
10.106.14.227/32
unicast-ip4-chain
[@0]: dpo-load-balance: [proto:ip4 index:38 buckets:1 uRPF:43 to:[0:0]]
[0] [@5]: ipv4 via 0.0.0.0 upf_session1: mtu:9000
What I was expecting that between ip4-rewrite and upf-if-input
the vnet_interface_output_node function of the software interface would be
invoked.
As far as I can see that is the only logical place that would calculate
check sums and do segmentation on for software interfaces.
For routed traffic that is normally not needed, but locally generated
traffic (like a local TCP endpoint) needs it.
It feels like I'm missing a important piece of the picture here.
What function or node should fill in the checksum for locally generate
traffic before it is encapsulated into a tunnel and what might be wrong
that it does not work in my setup?
Many Thanks,
Andreas
Am Mo., 29. Apr. 2019 um 16:59 Uhr schrieb Dave Barach (dbarach) <
dbar...@cisco.com>:
> Try “pcap dispatch trace on max 10000 buffer-trace
> <rx-interface-input-node> 1000”, cause a transaction, “pcap dispatch trace
> off”; then look at the resulting trace w/ a vpp-dispatch-trace enabled
> wireshark. See
> https://fdio-vpp.readthedocs.io/en/latest/gettingstarted/developers/buildwireshark.html
>
>
>
> HTH... Dave
>
>
>
>
>
> *From: *<vpp-dev@lists.fd.io> on behalf of Andreas Schultz <
> andreas.schu...@travelping.com>
> *Date: *Monday, April 29, 2019 at 9:31 AM
> *To: *"vpp-dev@lists.fd.io" <vpp-dev@lists.fd.io>
> *Subject: *[vpp-dev] how to trace tcp4-output?
>
>
>
> Hi,
>
>
>
> I'm trying to debug a problem and need to trace tcp4-output with vpp 19.04.
>
>
>
> So far I have tried it with "trace add tcp4-output 100 verbose", but that
> is not producing the expected result. The trace buffer is always empty.
>
>
>
> I was expecting that "trace add af-packet-input 100" would also trace the
> replies. But I can only see the incoming TCP-SYN, the generated SYN+ACK and
> the tcp4-output nodes are not showing up in the trace.
>
> I do know that the SYN+ACK gets generate, because I can see it in tcpdump
> after it has gone through an encapsulation.
>
>
>
> The problem I'm trying to figure out is why the TCP SYN+ACK packet when it
> hits a tunnel encapsulation node has invalid (or even no) check sums. I
> suspect there is something going on with the csum offload. But without the
> trace, finding that problem is a nightmare.
>
>
>
> Many thanks,
>
> Andreas
>
>
>
>
>
> --
>
> --
> Dipl.-Inform. Andreas Schultz
>
> ----------------------- enabling your networks ----------------------
> Travelping GmbH Phone: +49-391-81 90 99 0
> Roentgenstr. 13 Fax: +49-391-81 90 99 299
> 39108 Magdeburg Email: i...@travelping.com
> GERMANY Web: http://www.travelping.com
>
> Company Registration: Amtsgericht Stendal Reg No.: HRB 10578
>
> Geschaeftsfuehrer: Holger Winkelmann VAT ID No.: DE236673780
> ---------------------------------------------------------------------
>
--
--
Dipl.-Inform. Andreas Schultz
----------------------- enabling your networks ----------------------
Travelping GmbH Phone: +49-391-81 90 99 0
Roentgenstr. 13 Fax: +49-391-81 90 99 299
39108 Magdeburg Email: i...@travelping.com
GERMANY Web: http://www.travelping.com
Company Registration: Amtsgericht Stendal Reg No.: HRB 10578
Geschaeftsfuehrer: Holger Winkelmann VAT ID No.: DE236673780
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