Re: NBAP -> RRC Help

["Anders Broman" <anders.broman () ericsson com>]

Hi,
Abstracts from the ASN1 descriptions:
NBAP:
IB-SG-DATA ::= BIT STRING

-- Contains SIB data fixed" or "SIB data variable" in segment as encoded
in ref.[18].

RRC
SIB-Data-fixed ::= BIT STRING (SIZE (222))

SIB-Data-variable ::= BIT STRING (SIZE (1..214))

In principle you could "export" SIB-Data-fixed  and SIB-Data-variable
dissection from RRC, include packet-rrc.h in NBAP and use the metodes
there but as yopu can see that wouldn't add much...
 
> From a quick read of the spec it's not clear to me if 
 iB-Type: mIB (0)
Idicates that the field actually contains a masterInformationBlock and
could be decoded as such.
 
Regards
Anders

________________________________

From: wireshark-dev-bounces () wireshark org
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Rick Bywater
Sent: den 10 november 2009 15:21
To: wireshark-dev () wireshark org
Subject: [Wireshark-dev] NBAP -> RRC Help


All,

I am looking at the NBAP dissector to correct/complete its decode of
IB_SG_DATA.  According to the specifications, the IB_SG_DATA has RRC
encoding.  So, for each IE IB_SG_DATA IE, the RRC dissector for that
segment (presumably) should be called.  Currently, those IEs simply
decode as bit string?  Here is an abbreviated section of the decode I am
talking about:

Frame 1 (330 bytes on wire, 330 bytes captured)
Ethernet II, Src: Dell_ed:a0:a4 (00:11:43:ed:a0:a4), Dst:
DellComp_f2:3c:f1 (00:b0:d0:f2:3c:f1)
Internet Protocol, Src: 172.16.5.201 (172.16.5.201), Dst: 10.30.86.200
(10.30.86.200)
Stream Control Transmission Protocol, Src Port: 49153 (49153), Dst Port:
49152 (49152)
UTRAN Iub interface NBAP signalling
    NBAP-PDU: initiatingMessage (0)
        initiatingMessage
            procedureID
                procedureCode: id-systemInformationUpdate (32)
                ddMode: common (2)
            criticality: reject (0)
            messageDiscriminator: common (0)
            transactionID: longTransActionId (1)
                longTransActionId: 80
            value
                SystemInformationUpdateRequest
                    protocolIEs: 2 items
                        Item 0: id-C-ID
                            ProtocolIE-Field
                                id: id-C-ID (25)
                                criticality: reject (0)
                                value
                                    C-ID: 0
                        Item 1:
id-MIB-SB-SIB-InformationList-SystemInfoUpdateRqst
                            ProtocolIE-Field
                                id:
id-MIB-SB-SIB-InformationList-SystemInfoUpdateRqst (134)
                                criticality: reject (0)
                                value
 
MIB-SB-SIB-InformationList-SystemInfoUpdateRqst: 7 items
                                        Item 0
 
MIB-SB-SIB-InformationItem-SystemInfoUpdateRqst
                                                iB-Type: mIB (0)
                                                iB-OC-ID: 1
                                                deletionIndicator:
no-Deletion (0)
                                                    no-Deletion:
id-SegmentInformationListIE-SystemInfoUpdate
                                                        iB-SG-REP: rep8
(1)
 
segmentInformationList
                                                            id:
id-SegmentInformationListIE-SystemInfoUpdate (266)
                                                            criticality:
reject (0)
                                                            value
 
SegmentInformationListIE-SystemInfoUpdate: 1 item
                                                                    Item
0
 
SegmentInformationItem-SystemInfoUpdate
 
iB-SG-POS: 0
 
segment-Type: complete-SIB (5)
 
iB-SG-DATA: 609104650004062120321101990C8D4400D01CA880E8 [bit length
176]


So, my question is how is that done?  Can a higher level dissector be
invoked via an ASN.1 dissector while returning back later to finish
decoding the remaining IEs?  If so, where is an example I can follow?



Thanks,
Rick

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