Re: [PATCH net-next 09/14] gtp: Allow configuring GTP interface as standalone

On Wed, Sep 20, 2017 at 8:27 AM, Andreas Schultz [off-list ref] wrote:

On 19/09/17 02:38, Tom Herbert wrote:

quoted

Add new configuration of GTP interfaces that allow specifying a port to
listen on (as opposed to having to get sockets from a userspace control
plane). This allows GTP interfaces to be configured and the data path
tested without requiring a GTP-C daemon.

This would imply that you can have multiple independent GTP sockets on the
same IP address.That is not permitted by the GTP specifications. 3GPP TS
29.281, section 4.3 states clearly that there is "only" one GTP entity per
IP address.A PDP context is defined by the destination IP and the TEID. The
destination port is not part of the identity of a PDP context.

We are in no way trying change GTP, if someone runs this in a real GTP
network then they need to abide by the specification. However, there
is nothing inconsistent and it breaks nothing if someone wishes to use
different port numbers in their own private network for testing or
development purposes. Every other UDP application that has assigned
port number allows configurable ports, I don't see that GTP is so
special that it should be an exception.

Tom