Dear Harald,
Sorry to spam the openbsc list with this, but if you (or someone) can confirm if the Sgsn-emu part of Osmo-GGSN utilizing the kernel GTP module or not, that would be lovely.
FYI, I was not able to pass more than 280Mbit and the sgsn-emu process was maxing out a single core. Based on this I suspect that it does not use the kernel GTP module. I have seen some commits that indicates preparation work for this feature, but it is unclear at least to me, if this was finished or not. In the Osmo-GGSN.cfg example config I can see the config option for kernel GTP, but not in the sgsn-emu.cfg example.
Regards, Csaba
Hi Csaba,
On 12/22/22 15:00, Sipos Csaba wrote:
Dear Harald,
Sorry to spam the openbsc list with this, but if you (or someone) can confirm if the Sgsn-emu part of Osmo-GGSN utilizing the kernel GTP module or not, that would be lovely.
sgsnemu is not using the kernel module, only osmo-ggsn has support for it so far.
See osmo-ggsn.git/./sgsnemu/sgsnemu.c line 1905 calling: """ if (tun_new((struct tun_t **)&tun, options.tun_dev_name, false, -1, -1)) """
See tun_new() function used by both osmo-ggsn and sgsnemu: """ int tun_new(struct tun_t **tun, const char *dev_name, bool use_kernel, int fd0, int fd1u) { """
So sgsnemu is passing use_kernel=false, which makes the lib skip gtp-kernel functions like gtp_kernel_create().
FYI, I was not able to pass more than 280Mbit and the sgsn-emu process was maxing out a single core. Based on this I suspect that it does not use the kernel GTP module. I have seen some commits that indicates preparation work for this feature, but it is unclear at least to me, if this was finished or not. In the Osmo-GGSN.cfg example config I can see the config option for kernel GTP, but not in the sgsn-emu.cfg example.
You could try passing use_kernel=true to tun_new(), and see how far you can get. Patches welcome.
Regards, Pau
Hi Csaba and Pau,
On Fri, Dec 23, 2022 at 06:38:55PM +0100, Pau Espin Pedrol wrote:
You could try passing use_kernel=true to tun_new(), and see how far you can get. Patches welcome.
The GTP kernel module needs to be told if it operates in SGSN or GGSN mode.
grep for GTP_ROLE_SGSN in libgtpnl. I don't know all of the related functions off my head, but on the SGSN side you need to make sure to initialize the kernel GTP with GTP_ROLE_SGSN instead of GTP_ROLE_GGSN.
Hi Harald and Pau,
The GTP_ROLE_SGSN part is set in gtp_new(), for both the sgsn-emu.c and the ggsn.c code. What I cant figure out is what to change in order for that to be passed to the GTP kernel module... Spent some time modifying the sgsnemu.c but the only thing I achieved was a segmentation fault...
I am not even sure how can I distinguish which part is using the kernel GTP headers and which part is using the internal GTP implementation...
Modifying the tun_new() function to set the use_kernel parameter to true is definitely not enough:
Line 1905 (sgsnemu.c):
if (tun_new((struct tun_t **)&tun, options.tun_dev_name, true, -1, -1)) {
Regards, Csaba
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Harald Welte -
Pau Espin Pedrol -
Sipos Csaba