Hi Jonas, Sorry, for later reply, I'm currently on vacation with almost no internet access.
----- On Feb 6, 2017, at 2:33 PM, Jonas Bonn jo...@southpole.se wrote: > Hi Pablo, > > On 02/06/2017 12:08 PM, Pablo Neira Ayuso wrote: >> Hi Jonas, >> >> On Fri, Feb 03, 2017 at 10:12:31AM +0100, Jonas Bonn wrote: >>> The GTP-tunnel driver is explicitly GGSN-side as it searches for PDP >>> contexts based on the incoming packets _destination_ address. If we >>> want to write an SGSN, then we want to be idenityfing PDP contexts >>> based on _source_ address. >>> >>> This patch adds a "flags" argument at GTP-link creation time to specify >>> whether we are on the GGSN or SGSN side of the tunnel; this flag is then >>> used to determine which part of the IP packet to use in determining >>> the PDP context. >> So far the implementation that I saw in osmocom relies on userspace code >> to tunnel data from ME to the SSGN/SGW running on the base station. >> >> The data we get from GGSN -> SGSN needs to be places into a SN-PDU (via >> SNDCP) when sending it to the BTS, right? So I wonder how this can be >> useful given that we would need to see real IP packets coming to the >> SSGN that we tunnel into GTP. > > Fair enough. The use-case I am looking at involves PGW load-testing > where the simulated load is generated locally on the SGSN so it _is_ > seeing IP packets and the SNDCP is left out altogether. Perhaps this is > too pathological to warrant messing with the upstream driver... I don't > know: the symmetry does not cost much even if it's of limited use. Sounds reasonable. I'll review change with that in mind next week. Andreas > Couldn't the SNDCP theoretically be a separate node and push IP packets > to the SGSN, thus making this useful? Perhaps it's a stretch... > > /Jonas
