Problem with SGSN Location Update Reject during UE attach
Dear all We are facing the following problem and hope you can help us: - We use OSMO as UMTS core emulation, working with our real NodeB - During UE attach procedure we see from SGSN "Location Update Reject" and afterthat UE is released. - We do the comparison test with real UMTS core and our real NodeB, here it works properly, UE can attach successful. We assume there is some Osmo configuration problem but we have not found the root cause, we very appreciate if you can take a look and give us some advice. Here is the current message flow of UE attach 10.2.9.200 10.2.9.139 RANAP 170 (RUA) InitialUE-Message (DTAP) (MM) Location Updating Request 10.2.9.139 10.2.9.200 RANAP 158 SACK (RUA) DirectTransfer (DTAP) (MM) Authentication Request 10.2.9.200 10.2.9.139 RANAP 222 SACK (RUA) InitialUE-Message (DTAP) (GMM) Attach Request 10.2.9.139 10.2.9.200 RANAP 122 SACK (RUA) DirectTransfer (DTAP) (GMM) Identity Request 10.2.9.200 10.2.9.139 RANAP 118 (RUA) DirectTransfer (DTAP) (MM) Authentication Failure 10.2.9.139 10.2.9.200 RANAP 158 SACK (RUA) DirectTransfer (DTAP) (MM) Authentication Request 10.2.9.200 10.2.9.139 RANAP 154 SACK (RUA) DirectTransfer (DTAP) (GMM) Identity Response 10.2.9.139 10.2.9.200 RANAP 162 SACK (RUA) DirectTransfer (DTAP) (GMM) Authentication and Ciphering Req 10.2.9.200 10.2.9.139 RANAP 110 (RUA) DirectTransfer (DTAP) (MM) Authentication Response 10.2.9.139 10.2.9.200 RANAP 138 SACK (RUA) SecurityModeCommand 10.2.9.200 10.2.9.139 RANAP 98 (RUA) SecurityModeComplete 10.2.9.139 10.2.9.200 RANAP 122 SACK (RUA) CommonID 10.2.9.200 10.2.9.139 RANAP 166 SACK (RUA) DirectTransfer (DTAP) (GMM) Authentication and Ciphering Resp 10.2.9.139 10.2.9.200 RANAP 134 SACK (RUA) DirectTransfer (DTAP) (MM) Location Updating Accept 10.2.9.139 10.2.9.200 RANAP 122 (RUA) SecurityModeCommand --> 10.2.9.139 10.2.9.200 RANAP 106 (RUA) DirectTransfer (DTAP) (MM) Location Updating Reject 10.2.9.139 10.2.9.200 RANAP 102 (RUA) Iu-ReleaseCommand 10.2.9.200 10.2.9.139 RANAP 114 SACK (RUA) Iu-ReleaseComplete 10.2.9.200 10.2.9.139 RANAP 102 (RUA) SecurityModeReject 10.2.9.200 10.2.9.139 RANAP 102 (RUA) Iu-ReleaseRequest 10.2.9.139 10.2.9.200 RANAP 118 SACK (RUA) Iu-ReleaseCommand 10.2.9.200 10.2.9.139 RANAP 114 SACK (RUA) Iu-ReleaseComplete Thanks and regards Tuan Lam
Surely you have noticed the MM Location Updating Reject message in your pcap. You are attaching fine to the SGSN (GMM), but are being rejected by the MSC (MM). Hence your phone doesn't like it and leaves. ~N
Actually, the GMM attach doesn't complete, either. The messages look a bit confusing, with a bunch of Location Updating Accept followed by a final Location Updating Reject due to "Congestion". The causes may be - two simultaneous MM attach requests from the same subscriber, - timeout after attaching, e.g. phone sends no TMSI Reallocation Complete It's hard for me to see what is going on there, take a look at the MSC's logs. As soon as the MSC attach works out, the phone will continue to try at the SGSN. ~N
Hello Mr. Neels Hofmeyr Vielen Dank fuer die schnelle Antwort :-) Actually we also have seen the "Congestion" in the log but we have not understood why We have modified the SGSN configuration: set auth-policy to accept-all. We repeat the UE attach with this configuration but still MSC sends "Location Update Reject" I attach the new pcap file, msc log and sgsn log. I very appreciate if you can take a look to that. Vielen Dank Tuan Lam -----Original Message----- From: Neels Hofmeyr [mailto:nhofmeyr@sysmocom.de] Sent: Tuesday, October 16, 2018 5:43 PM To: Lam Ngoc Tuan Cc: osmocom-net-gprs@lists.osmocom.org Subject: Re: Problem with SGSN Location Update Reject during UE attach Actually, the GMM attach doesn't complete, either. The messages look a bit confusing, with a bunch of Location Updating Accept followed by a final Location Updating Reject due to "Congestion". The causes may be - two simultaneous MM attach requests from the same subscriber, - timeout after attaching, e.g. phone sends no TMSI Reallocation Complete It's hard for me to see what is going on there, take a look at the MSC's logs. As soon as the MSC attach works out, the phone will continue to try at the SGSN. ~N
On Tue, Oct 16, 2018 at 05:59:08PM +0700, Lam Ngoc Tuan wrote:
We have modified the SGSN configuration: set auth-policy to accept-all.
No. For 3G, you require authentication, hence you need an external HLR that provides auth tuples, for both MSC and SGSN. I was unable to extract the attached rar file, please send a .tar or .tar.gz instead, or even better, just post a link to a pastebin, so we don't fill up people's mail inboxes. In your first trace it seems that your authentication did work out, i.e. HLR configured properly, but in the end the UE failed to respond with a TMSI Reallocation Complete. That's a very weird situation, I would normally associate that with an unreliable / unaccurate SDR based solution. But I assume you are using a nano3G? ~N
participants (2)
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Lam Ngoc Tuan -
Neels Hofmeyr