1. 0 Considerations on T2S Migration: Special contingency cases during migration T2S Programme Office European Central Bank T2S Advisory Group - 19 November 2013 ECB-PUBLIC Item 6.3 09.04.01/2013/018417

2. 1 Special contingency cases during migration Background  During the last months, the MSG worked on identification of major contingency scenarios applicable to the migration weekend  While for certain scenarios the way forward is clearly identified, some other issues were more difficult to apprehend:  Case 1: One CSD can not migrate as originally planned  Possible options to address this issue:  Move affected CSD to the contingency migration wave  Postpone complete migration wave  Case 2: Entire migration wave cannot migrate as originally planned  Possible options to address this issue:  Move the entire wave to the contingency wave  Postpone to a later migration date

3. 2 Special contingency cases during migration Issue – One CSD can not migrate as originally planned Case 1:  How should we manage the issue of one CSD not being able to migrate as originally planned and leaving the migration wave?  Current plan to address this issue:  Exclude affected CSD and postpone its migration to the contingency wave  Remaining CSDs/CBs are to continue their migration

4. 3 Special contingency cases during migration Points for consideration - One CSD can not migrate  Current plan aims at minimising the impact on remaining CSDs/CBs and their communities:  They have spent a lot of effort in adapting & testing, made important investment and are ready to migrate as scheduled  Their business case could be dependent on timely implementation of migration  But have all implications been measured?  Current plan implies an untested migration wave composition and a new adaptation model to be defined and implemented:  Contingency configuration can not be prepared and tested in advance due to significant number of wave composition variations  Additional activities are needed in order to address this contingency scenario:  Revision of cross-CSD link configuration in T2S  Resurrection of legacy links and back office systems Changing composition of migration wave and continuing migration for remaining CSDs/CBs

5. 4 Special contingency cases during migration Points for consideration - One CSD can not migrate Changing composition of migration wave and continuing migration for remaining CSDs/CBs Existing systems/procedures before migration weekend T2S CSD A1 Before migration weekend DCP T2S CSD A1 DCP CSD B1 CSD B2 B1 B2 B1 B2 Planned migration weekend T2S CSD A1 DCP CSD B1 CSD B2 A1 B2 B1 Contingency migration weekend Systems/procedures planned for migration weekend Adapted systems/procedures due to contingency case T2S (A1, B2) T2S T2S (A1) T2S (B1, B2)T2S (A1, B2) T2S (A1, B1) T2S (A1, B1, B2) T2S (B2) CSD B1 A1 B2 Legend CSD B2 A1 B1 Revision of T2S system/procedures Resurrection of the legacy systems/procedures

6. 5 Special contingency cases during migration Points for consideration - One CSD can not migrate Special variation: CSD without links unable to migrate and rescheduled to contingency wave Existing systems/procedures before migration weekend T2S CSD A1 Before migration weekend DCP T2S CSD A1 DCP CSD B1 CSD B2 B2 B1 B2 Planned migration weekend T2S CSD A1 DCP CSD B1 CSD B2 B1 Contingency migration weekend Systems/procedures planned for migration weekend Adapted systems/procedures due to contingency case T2S (A1, B2) T2S T2S (A1) T2S (B2) T2S (A1) T2S (A1, B1, B2) CSD B1 CSD B2 A1 Revision of T2S system/procedures Resurrection of the legacy systems/procedures T2S (B2) T2S (A1) Legend

7. 6 Special contingency cases during migration Issue – Entire migration wave can not migrate as originally planned Case 2:  How should we manage the issue of an entire migration wave not being able to migrate as originally planned, requiring the postponement of the complete migration wave?  Option A – Reschedule entire wave to contingency wave  Solution implies a change of migration order with no impact on the timing of subsequent waves  Option B – Postpone affected wave to a later migration date  Solution implies a timing impact on subsequent waves but no change of migration order

8. 7 Special contingency cases during migration Points for consideration - Entire migration wave can not migrate  Option A – Rescheduling to contingency wave:  Overall migration planning remains stable, i.e. communicated migration dates of subsequent waves are still valid  Configuration of remaining waves will need to be revised and legacy systems/procedures will need to be resurrected (  similar to scenario of rescheduling the migration of single CSD to contingency wave)  Option B – Postponing affected and subsequent migration waves:  Efforts in user testing and migration preparation are secured, as re-testing is limited to issue resolution  Identifying and planning of alternate migration dates is challenging, as time needed to resolve issue causing the postponement is unknown in advance Pros and cons of both options