  Networks such as the Internet are essential for our connected world. Quantum
computing poses a threat to this heterogeneous infrastructure since it
threatens fundamental security mechanisms. Therefore, a migration to
post-quantum-cryptography (PQC) is necessary for networks and their components.
At the moment, there is little knowledge on how such migrations should be
structured and implemented in practice. Our systematic literature review
addresses migration approaches for IP networks towards PQC. It surveys papers
about the migration process and exemplary real-world software system
migrations. On the process side, we found that terminology, migration steps,
and roles are not defined precisely or consistently across the literature.
Still, we identified four major phases and appropriate substeps which we
matched with also emerging archetypes of roles. In terms of real-world
migrations, we see that reports used several different PQC implementations and
hybrid solutions for migrations of systems belonging to a wide range of system
types. Across all papers we noticed three major challenges for adopters:
missing experience of PQC and a high realization effort, concerns about the
security of the upcoming system, and finally, high complexity. Our findings
indicate that recent standardization efforts already push quantum-safe
networking forward. However, the literature is still not in consensus about
definitions and best practices. Implementations are mostly experimental and not
necessarily practical, leading to an overall chaotic situation. To better grasp
this fast moving field of (applied) research, our systematic literature review
provides a comprehensive overview of its current state and serves as a starting
point for delving into the matter of PQC migration.
