EOL vs. EOS vs. EOSL
Three acronyms, three different dates, years apart.
Last reviewed
End-of-Sale (EOS), End-of-Life (EOL), and End-of-Service-Life (EOSL) mark different stages of a network product's lifecycle. They are not interchangeable. Confusing EOS with EOL — the most common mistake — either triggers a premature forklift upgrade of hardware that's still fully supported, or leaves unsupported gear running because someone assumed "end of sale" meant the vendor would still patch it.
End-of-Sale (EOS)
The vendor stops selling the product. You can no longer place new orders or last-time-buy after a specified date. But the vendor continues full support — software updates, security patches, TAC/JTAC cases, RMA — for years after this date.
EOS is a purchasing milestone, not a support milestone. A device that is end-of-sale but still within its support window is fully supported hardware. Replacing it solely because it's "EOS" is wasting budget.
End-of-Life (EOL)
The vendor ends all support. No patches, no TAC cases, no RMA. The product is operationally dead. This is the date that matters for security and compliance.
"End-of-Life" is also used as a blanket term for the entire wind-down process, which causes confusion. On this site, the authoritative field is Last Date of Support — the final day the vendor provides any support of any kind. That's the hard cutoff.
End-of-Service-Life (EOSL)
Used by some vendors (Juniper, HPE) as a synonym for the final support cutoff — equivalent to what Cisco calls "Last Date of Support" and what this site labels End-of-Life. It means the same thing: support is over.
The timeline
For most vendors, the sequence runs: Announcement → End-of-Sale → End-of-Software-Maintenance → End-of-Security-Support → Last Date of Support (EOL). The gap between EOS and EOL is typically 3–5 years, depending on the vendor.
The critical inflection point is End-of-Security-Support (or the vendor's equivalent — Cisco calls it "End of Vulnerability/Security Support," Juniper calls it "End of Engineering"). After that date, no security patches are issued. The device is a permanent, expanding attack surface. See the terminology cross-reference for how each vendor names each milestone.