Attention is currently required from: pespin, daniel, lynxis lazus.

fixeria has posted comments on this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/32176 )

Change subject: gprs: fix has_valid_nsvc(): permit local udp port 0 ......................................................................

Patch Set 1:

(1 comment)

Patchset:

PS1:

(Copy-pasting from previous Change-Id:)

What previous Change-Id? It's a new patch. I am guessing you meant: https://gerrit.osmocom.org/c/osmo-bsc/+/32169.

The question here is more: does it make sense from network architecture point of view that PCU binds to a randomly available port for Gb?

You have to use a different bind port anyway when running everything on the same host. I have 23023 in my config file, which does not clash with 23000 used by osmo-sgsn by default. I see random bind port selection as a useful option, removing the need to pick and configure it manually.

AFAIU it makes no sense, since it needs to bind to a specific port also known by the SGSN so that it knows where to send packets to. Or is the SGSN available to learn dynamically of the PCU by listening() on its port?

AFAIU, osmo-sgsn "learns" the PCU's bind port during the initial NS handshake, yes. So it needs not to be known by the SGSN in advance. There is no config options in osmo-sgsn to specify the bind addresses of PCUs.

I also confirmed in the leaked ip.access A-bis document that 0 is a valid special value, which tells the PCU to bind() at a random port number.