A factory connects a new MDS to a SAN whose device aliases run in basic mode. The new switch is in enhanced device-alias mode. The ISL comes up, but the device-alias databases never merge. Why?
Select an answer to reveal the explanation.
Short Explanation
You can have the phone line up and still get the ledger slammed shut. Device-alias distribution refuses to merge a basic-mode database with an enhanced-mode database, even though the ISL itself is fine.
Full Explanation
Cisco Fabric Services merges the device-alias database when a new switch joins. Basic mode and enhanced mode are not converted automatically. If the fabrics disagree, the merge fails and each side keeps its own database. That is this factory's break. A missing commit would matter if distribution were already in one mode and a staged edit had not been committed. It does not explain a mode mismatch, and the mode is the reason this merge stops. An fcalias is a VSAN-local alias and is a different object from a device alias. Enhanced device-alias mode does not turn device aliases into fcaliases, and it does not block every merge. The principal switch and the domain IDs decide domain ownership. They are not the device-alias mode check. Caveat: from MDS NX-OS 8.5(1), a new switch defaults to enhanced mode, so a new switch dropped onto an older basic-mode fabric hits this failure until you pick one mode for both. Operational check: show the device-alias merge status and confirm the reason is a mode mismatch before you change either side.