Ethernet edges get a veth pair created in the host namespace and then moved into the containers, named from the node ids alone. ethernet-mesh and ethernet-only both connect n01 to n04 and always run together, so one tore down the other's live link. Hash the scenario suffix to four hex characters and insert those after the vh prefix; 15 characters is far too few to carry the suffix itself.
The names are now run-specific and never regenerated, so the delete-before-create no longer reclaims an interface an earlier run abandoned. ci-cleanup.sh takes over, deriving the names from the suffixes a run's teardown hands it. It is the first thing that script removes that is neither a docker object nor labelled, so an unscoped reap can sever a running bare simulation's links; testing/README.md and the --reap help say so.
Chaos scenarios run four at a time under local CI, but every one of them claimed the container names fips-node-nNN and wrote its generated configs and compose file to the same generated-configs/sim directory. Container names are global in Docker and are not scoped by the compose project, so concurrent scenarios collided on both, and a scenario could start containers from a compose file another had overwritten.
Thread the existing FIPS_CI_NAME_SUFFIX into the simulation. run_chaos narrows the run-wide suffix to the scenario, and the sim reads it once when the topology is built, applying it to the container names and to the config directory basename. The compose template renders the name through the topology accessor instead of duplicating the literal, so one expression produces every chaos container name.
The suffix is empty when the variable is unset, so a bare chaos.sh run and the hosted CI jobs render byte-identical names and paths. Verified by rendering every scenario's compose file before and after with the variable unset and diffing.
Johnathan Corgan