MdVNE: Affected paths can lead to invalid embeddings

[maxkratz]

In some rare cases, the GIPS-based MdVNE algorithms can produce invalid embeddings of virtual networks onto substrate paths.

The edge case is:

• one virtual link vl1 gets mapped to a substrate path sp1 that consists of one (or more) substrate link(s) sl1.
• if another virtual link vl2 gets mapped to another substrate path sp2 that also (partly) consists of the substrate link sl1, its residual bandwidth value may be exceeded.

A test that sometimes shows this behavior is this test of the GIPS-based migration MdVNE algorithm: https://github.com/Echtzeitsysteme/iflye/blob/main/test.suite/src/test/algorithms/pm/migration/VnePmMdvneAlgorithmMigrationPathBandwidthBugTest.java

The more virtual networks one embeds at a time, the higher the probability to see triggering this error.