Why sometimes UERANSIM generates multiple NGAP messages within a single SCTP packet? (SCTP chukning)

[juan-montero-byd]

20240530a.zip

Sometimes (randomly), UERANSIM generates multiple NGAP messages within a single SCTP packet (SCTP chunking). Is there any way to control it? Although Open5GS process these messages successfully, I would like to know if there is a way to send 1 NGAP per SCTP packet. Here a couple of examples:

Thanks!

[linouxis9]

Hi @juan-montero-byd,

You would have to set the option SCTP_NODELAY on the socket (but it does not completely prevent SCTP chunk bundling), it's the default behavior of SCTP stack inside the Linux Kernel.

Cheers,
Valentin

[laf0rge]

Indeed as @linouxis9 mentioned, this is not an issue at all about UERANSIM. What you are experiencing is a property/behaviour of the SCTP protocol stack inside the Linux kernel.

[juan-montero-byd]

Sorry I missed the first reply. Thank you both! I'll attempt playing with the SCTP_NODELAY, but also learn more about the Linux kernel SCTP protocol stack