Wireshark analysis of NB-IoT injection network process

The new version of Wireshark can parse NB-IoT cell messages, and of course the stored message formats need to be converted to the. pcap format Wireshark can parse. The analytic format of Wireshark can be used to understand the protocol flow and the meaning of individual cells. Wireshark Setup Preparation 1, edit-by preferences->protocols->udp-> Try heuristic sub-dissectors first 2, analysis-enabled protocols-All enabled- > Search Skype related configuration removal->ok; setting "Enable all" is primarily to enable the LTE message resolution library, or only to increase the LTE message resolution enabled. Register the whole process
This process is the telecommunications network in the process, the basic embodiment of NB terminal processing sequence process. Basic order: Receive mib=> receive sib1=> receive Si (resolve the SIB) =>attach request trigger RRC Link--Authentication, encryption =>attach Complete = release link. MIB message parsing
MIB contains SFN high 4bits (low 6bits in the process of parsing mib[npbch), HFN low 2BITS,SIB1 message size and deployment mode information, so to parse SIB1 before you need to get the size of the time information through the MIB (SFN for scrambling code sequence calculation )。 SIB1 Message Parsing
The SIB1 message contains parameters such as network PLMN, TAI, selection, re-election parameters (parameters required for R, S criteria), SI configuration, and so on. Before parsing the SI message, we need to get the configuration parameters in the SIB1, including: Si window length, number and each Si different period, repetition, including SIB messages. Si message parsing
An SI can carry a plurality of SIB messages, this process has only one SI message, which contains SIB2, SIB3, SIB5, wherein the SIB2 contains the configuration of public resources, including public channel, timer and so on, and SIB3, SIB5 is mainly re-election parameters and the same frequency, The configuration of the different frequency cell. Attach message flow attach process messages are not resolved, the protocol is divided into Nas, as is non-access layer and access layer, where as message includes the establishment of RRC connection release, and the NAS process includes attach, authentication, encryption and so on. Talk about the difference between the previous 3G WCDMA: When the RRC is established, it can carry the upper-level NAS messages at the same time, which means that attach request can be carried at the same time in the attach process Rrcconnectionsetupcomplete.