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Bug #2735

Malformed RF RESource INDication

Added by msuraev about 3 years ago. Updated about 3 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
12/11/2017
Due date:
% Done:

100%

Spec Reference:

Description

In wireshark 2.4.3 there's error when decoding RSL message:

Frame 90: 73 bytes on wire (584 bits), 73 bytes captured (584 bits) on interface 0
Linux cooked capture
Internet Protocol Version 4, Src: 10.9.1.105, Dst: 10.9.1.105
Transmission Control Protocol, Src Port: 40478, Dst Port: 3003, Seq: 105, Ack: 25, Len: 5
IPA protocol ip.access, type: RSL
Radio Signalling Link (RSL)
    0001 000. = Message discriminator: TRX Management messages (8)
    .... ...0 = T bit: Not considered transparent by BTS
    .001 1001 = Message type: RF RESource INDication (0x19)
    Resource Information IE
[Malformed Packet: RSL]
    [Expert Info (Error/Malformed): Malformed Packet (Exception occurred)]
        [Malformed Packet (Exception occurred)]
        [Severity level: Error]
        [Group: Malformed]

Found using latest OsmoBSC master and osmo-bts-virtual with attached configuration.

malformed_rf_re.pcap.pcapng.gz malformed_rf_re.pcap.pcapng.gz 2.95 KB msuraev, 12/11/2017 11:35 AM
osmo-bsc.cfg osmo-bsc.cfg 4.01 KB msuraev, 12/11/2017 11:37 AM
osmo-bts.cfg osmo-bts.cfg 1.03 KB msuraev, 12/11/2017 11:37 AM

Related issues

Related to OsmoBSC - Bug #2711: wireshark claims SI 2ter is wrongClosed12/05/2017

Related to libosmocore - Bug #1635: RSL RELASE indication and other messages include L3 informationClosed03/08/2016

Related to libosmocore - Bug #2336: RSL_IE_L3_INFO 16 bit length is wrongClosed06/22/2017

Related to OsmoBTS - Feature #1569: Report RF interference levels as part of RF RESOURCE INDICATIONNew02/23/2016

Associated revisions

Revision 4848c2c4 (diff)
Added by pespin about 3 years ago

Fix malformed Resource Indication packet

Wireshark was showing a Malformed packet alert, and further
ivnestigation showed that "Resource Information" TLV was missing in the
packet. See GSM 08.58 sections 8.6.1 and 9.3.21 for more information.

Indicating interference level is not yet implemented, but at least now
we avoid sending a malformed packet.

Patch has been validated against a running setup with wireshark in my local PC.

Related: OS#2735

Change-Id: Ie97170811aaf8a089febfa20380ab48ea174056a

History

#1 Updated by msuraev about 3 years ago

  • Related to Bug #2711: wireshark claims SI 2ter is wrong added

#2 Updated by msuraev about 3 years ago

  • Related to Bug #1635: RSL RELASE indication and other messages include L3 information added

#3 Updated by msuraev about 3 years ago

  • Related to Bug #2336: RSL_IE_L3_INFO 16 bit length is wrong added

#4 Updated by pespin about 3 years ago

  • Assignee set to pespin

#5 Updated by pespin about 3 years ago

Related bits: GSM 08.58 sections 8.6.1 and 9.3.21

#6 Updated by pespin about 3 years ago

At first glance, it seems it's not yet implemented:

/* 8.6.1 sending RF RESOURCE INDICATION */
int rsl_tx_rf_res(struct gsm_bts_trx *trx)
{
    struct msgb *nmsg;

    LOGP(DRSL, LOGL_INFO, "Tx RSL RF RESource INDication\n");

    nmsg = rsl_msgb_alloc(sizeof(struct abis_rsl_common_hdr));
    if (!nmsg)
        return -ENOMEM;
    // FIXME: add interference levels of TRX
    rsl_trx_push_hdr(nmsg, RSL_MT_RF_RES_IND);
    nmsg->trx = trx;

    return abis_bts_rsl_sendmsg(nmsg);
}

At rx time:

static int abis_rsl_rx_trx(struct msgb *msg)
{
...
    case RSL_MT_RF_RES_IND:
        /* interference on idle channels of TRX */
        //DEBUGP(DRSL, "%s RF Resource Indication\n", gsm_trx_name(sign_link->trx));
        break;
...

We should at least fix the packet to contain a len=0 field at least.

#7 Updated by pespin about 3 years ago

  • Status changed from New to Feedback
  • % Done changed from 0 to 90

Fix provided in https://gerrit.osmocom.org/#/c/5273/

I'll create a new task to remember to implement the interference level information.

#8 Updated by pespin about 3 years ago

  • Related to Feature #1569: Report RF interference levels as part of RF RESOURCE INDICATION added

#9 Updated by pespin about 3 years ago

  • Status changed from Feedback to Resolved
  • % Done changed from 90 to 100

#10 Updated by laforge about 3 years ago

  • Status changed from Resolved to Closed

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