"Upon receiving the End of Initialization (M_EI_NA_1) from the controlled station", "the controlling station shall initialize the Session Key".
IEC 60870-5-101 and IEC 60870-5-104 require that each LRU send the EOI with its own CCA.
If the Controlled station has multiple LRU and only one USR: multiple Session Key Initializations occur simultaneously for the same USR.
See attached file.
Proposal
I think it can either be addressed by adding in the 3rd point in IEC 62351-5:2013:
1) The Controlling station shall start only one Session Key Initializations per configured USR, in case of reception of multiple EOI.
Or more a more generic statement:
2) Bind the USR and CAA to have a status machine. This can be useful for IEC 60870-5-101 serial connection with multiple controlled stations. Note that the max number of USR is limited to 2 bytes.
Discussion
Created
Status
In case of multiple logical remote units (LRU) contained in the same physical device, separate TLS connection shall be utilized, one per each LRU.
27 May 25
Approval (Editoral)
Is see 2 different topics in the comments above:
1) Multiple CAA in the same DUT: discussed below
2) "Multiple Virtual IEDs" in the same DUT: I agree that this topic can be discussed for a future improvement of the standard
Related to the first topic:
IEC 60870-5-101 clause 7.4.5 defines:
"A station interrogation request is issued to the controlled station
– if an ENDINIT is received from the controlled station, OR
– if the central station observes the loss of a link (unsuccessful repetitions of the link layer) and the link layer is available again."
Considering the "OR" statement above, the clarifications in attached picture, test cases 5.4.17.1 and 5.4.17.10 in IEC 60870-5-604, the 3rd point in IEC 62351-5:2013 Clause 8.2:
"Upon receiving the End of Initialization (M_EI_NA_1) from the controlled station or otherwise detecting that communications has been re-established"
I think the basic idea is that the Controlling station should detect the communication re-estabilished and continue with the proposed solution 1:
"The Controlling station shall start only one Session Key Initializations per configured USR, in case of reception of multiple EOI."
21 Mar 25
Discussion (red)
The previous two comments shall not be considered because they are related to the TISSUE #12 and not to #11
14 Mar 25
Discussion (red)
If the security extension is applied to IEC 60870-5-101 protocol the Test Command ASDU used would be C_TS_NA_1.
If the security extension is applied to IEC 60870-5-104 protocol the Test Command ASDU used would be C_TS_TA_1.
14 Mar 25
Discussion (red)
Subclause 8.2 shall be updated in points 4, 5, 6, 7, 8 and 9 as indicated in the attached picture.
14 Mar 25
Discussion (red)
The initialization of multiple logical remote units (LRU) shall be also considered for the future improvement of IEC TS 60870-5-7 ED2.
14 Mar 25
Discussion (red)
In case the controlled station is composed by 2 or more LRUs and each LRU is able to send an M_EI_NA_1, the controlling station shall be able to manage the security extension independently fro each LRU (identified by different Common Cddress), each with separated state machine and cryptographic material.