GTPv1 to GTPv0 Interworking on Inter-SGSN RA Update

[petarivanov99]

Hi,

I know that GTPv1 to GTPv0 interworking is not supported in 29.060. However, I was wondering what should happen when an MS creates a PDP Context through a GTPv1-capable SGSN and then moves to a GTPv0-capable one? If the SGSN Context Request procedure between the SGNSs succeeds(can this happen?), then how is the GGSN supposed to act on an Update PDP Context? This case also affects Secondary PDP contexts.

Generally, I am not sure how GSNs are supposed to act, because the GTPv1 PDP Contexts support more features than GTPv0 and the fallback scenarios are not documented, they seem to be rather best-practice.

The openggsn code handles both versions (from the GGSN side) without checking the current PDP Context version. Any information on how you think this should be handled?

[chantra]

Hum,

I am actually using openggsn for its libgtp stack which allowed me to build gtpdump (see the gtpdump branch on this repository).
My understanding is that GTPv1 GGSNs should be backward compatible with GTPv0, that is, they can handle establishment of GTPv0 sessions. I am not sure it should be able to bounce from one protocol to the other one. I am not even sure a SGSN will handover traffic to a GTPv0 only SGSN.

Also, this is an unofficial repository , which is here so I can keep my modification on the net, you should maybe launch that discussion at http://sourceforge.net/projects/ggsn/