1672   Allow connection Server and ServerAt to the same SCL.Subnetwork

Created: 17 Feb 2020

Status: Future Improvement

Part: Part 6 (2019; Edition 2.1)


Page: 87

Clause: 9.3.2

Paragraph: Below Table 50


it is not allowed to connect multiple Access Point of a Server to the same subnetwork.
The restriction has been identified during the last Interop TEst as being to restrictive and lead to interoperability problems.


During the TC57WG10 Meeting in Golden, it was decided to remove the restriction as follow:
- define a new Service Capability to indicate that multiple APs of a server can be connected to the same subnetwork,
- the SCT shall provide the apRef while configuring GOOSE, SMV, and Report subscription.
- the IP address asignement by the SCT shall be careful, as using IP addresses in the same IP network for different ConnectedAP of a server may lead to communication problem with OS like Windows, Linux.

Discussion Created Status
Moved to future improvement. It will be integrated in an Edition 2.2 13 Jul 20 Future Improvement
move to Future Improvement - the solution of the problem will be integrated in IEC 61850-6 Ed2.2.
22 Jun 20 Approval (Future Improvement)
Discussions about
- compatibility handling have shown the backward compatibility aspects are to be addressed within SCL downgrading rules,
- data flow configuration restriction based on exposed new serviceCapability or not, are to be captured in a broader environment than a tissue resolution.
The issue solution is postponed to the IEC 61850-6 Amendment 2.2, which RevisionRequest is currenlty being drafted.
Therefore the Ed2.1 limitation of 1 ConneectedAP of a Server/ServerAt connected to the same subnetwork still exists for the SCT.

22 Jun 20 Discussion (red)
Imagine the following configuration:
A server has 2 AccessPont P1, and P2. The following IP configuration is made: the 2 aacess point have IP addresses in the same IP subnetwork:
Server->ConnectedAP P1->
->ConnectedAP P2->

An IP stack in the server will have problem to answer to IP telegram over the correct access point / ethernet controller.
The problem exists today, even when the 2 ConnectedAP are NOT connected onto the same SCL.SubNetwork.

Therefore, the IP address configuration shall ensure that ConnectedAPs of the same Server does not get IP addresses in the same IP subnetwork.

Server->ConnectedAP P1->
->ConnectedAP P2->
is a correct IP configuration.
P1 is member of IP subnetwork 192.168.1 while
P2 is member of IP subnetwork 192.168.2

The proposal includes:

the IP address assignment by the SCT shall be careful, and not assign IP addresses in the same IP subnetwork to ConnectedAP of an IED.
(here regardless of Server / Client - restricution applies to ConnectedAP).
25 Feb 20 Accepted


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