TCP Loss Reported In OSB/SCA 12.2.1.4 Hosts (Doc ID 2832340.1)

Last updated on NOVEMBER 16, 2023

Applies to:

Goal

Tcpdump files show multiple occurrences of dropped packets at the TCP layer.
These losses were not restricted to one particular source and destination.

In general, three events related to TCP packet loss were observed:

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1. TCP Previous segment lost:

Wireshark filter: tcp.analysis.lost_segment

Occurs when a packet arrives with a sequence number greater than the "next
expected sequence number" on that connection, indicating that one or more
packets prior to the flagged packet did not arrive. This event is a good
indicator of packet loss and will likely be accompanied by duplicate ACKs,
which leads to retransmissions.

========================
2. TCP Retransmission:

Wireshark filter: tcp.analysis.retransmission

Occurs when the sender retransmits a packet after the expiration of the
acknowledgement. A few retransmissions are OK, excessive retransmissions are
bad. This usually shows up as slow application performance and/or packet loss
to the user.

========================
3. TCP ZeroWindow:

Wireshark Filter: “tcp.analysis.zero_window”

Occurs when a receiver advertises a receive window size of zero. This
effectively tells the sender to stop sending because the receiver's buffer is
full. Indicates a resource issue on the receiver, as the application is not
retrieving data from the TCP buffer in a timely manner.

Here is the O/S information:
$ uname -a
Linux ... 3.10.0-1127.13.1.el7.x86_64 #1 SMP Fri Jun 12 14:34:17 EDT 2020
x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.9 (Maipo)

1) What kernel parameters can be set to resolve TCP packet loss in SOA/OSB
12.2.1.4.0?
2) Are the TCP tuning recommendations in the EDG the only ones recommended by
the SOA product?
 

Solution

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