You can freely build on How DNS Servers Route Web Traffic to the Least Busy Server
This patent expired in 2017. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Cisco Technology Inc
Patent granted
2001
Expired
2017
Forward citations
123
What this patent covers
This patent describes a system where multiple web servers share a single domain name (like www.example.com). Each server monitors its own performance by measuring how long it takes to respond to requests and how many clients are currently waiting. The servers send these performance metrics to a central DNS server. When a new user tries to visit the site, the DNS server uses this data to calculate which server is currently the least busy and sends the user to that specific machine's network address.
What is now free to use
All 0 claims of US 6178160 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover load balancing performed by hardware appliances like dedicated load balancers sitting in front of servers.
Does not cover client-side selection where the user's browser decides which server to connect to.
Does not cover simple round-robin DNS where servers are chosen in a fixed sequence regardless of their actual performance.
Who is building on this today
Cisco remains a major player in networking hardware, but this logic is now standard practice across major cloud providers like Amazon Web Services (AWS), Google Cloud, and Microsoft Azure. These companies have evolved these concepts into highly sophisticated, automated traffic management systems.
Products built on expired version of this technology
Early web server clusters
Global Server Load Balancing (GSLB) systems
Content Delivery Network (CDN) routing logic
How to cite this patent in your documentation
Cisco Technology Inc. US Patent 6178160. Load balancing of client connections across a network using server based algorithms. Granted 2001, expired 2017. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.