• layer 7 Global Load Balancing and Fail-Over Clustering - Virtual Domain
• Layer 3 Local IP Load Balancing and Fail-Over - Virtual IP
• Unprecedented High Availability - eliminate all single point of failure for 100% Uptime
• Unprecedented Scalability - large-scale expansion of servers, up to 1 Million Cluster Groups and 4096 Cluster Nodes
• XGFORCE Dynamic Server Feedback Protocol
• Inter-Cluster Clustering - Load Balance and Fail Over among Unlimited Number of Clusters and Data Centers (Virtual IP is available in Load Balancer/SUN SPARC/FreeBSD with Layer 3 driver.)
• SQL Database Clustering
• SSL Encrypted and Compressed Communication (47:1 ratio) Channel
• Persistent Cookies Switching
• Persistent SSL Packet Switching
• Clustering Algorithm and Rules such as CPU Usage, Load Average, Weighted Load Average, VM Usage, Geographic Proximity (Version 3.8), RTT, Fail Over, and File System Space, Number of Processes, Least Connections, Maximum Connections
• Application Server Port Load Balance and Fail Over
• Scriptability to Take a Server On-Line/Off-Line
• Content Aware Clustering - URL Fail Over, Cold Fusion Fail Over, SQL Fail Over (If one of the URL failed, an automatic fail-over will take place.)
• Firewall and VPN (Available in Load Balancer product, SUN SPARC Solaris, FreeBSD with Layer 3 Driver) with Stateful Packet Inspection
• Preventing Denial of Service (DoS), TCP SYN Attacks, SMURF Attacks, FIN and XMAS scans 
• Packet State Engine - keep track of whether or not a connection is established, works with TCP, UDP and ICMP
• Bandwidth Management and Traffic Shaper
• IP Version 6 Support
• E-Mail Alert for Malfunctions
• CFS, the Clustered File System (add-on)
• Platform Supported, Windows NT 2000/XP, SUN SPARC/INTEL, FreeBSD, OS2000, Linux.
• Cluster Agent Available for Windows NT 4/2000/2003/XP, SUN SPARC, FreeBSD, NetBSD, OS2000, Linux.
• Example Load Balance and Fail Over Applications:
  • WAN Links
  • Servers
  • Firewalls
  • VPNs
  • Search Engines
  • Intrusion Detection Systems
  • LDAP
  • DNS servers
  • MS COM/DCOM
  • Streaming Media - Real Time Streaming Protocol (RTSP)
  • Wireless Internet - Wireless Application Protocol (WAP)
  • VoIP Gateways
  • SIP
  • WebLogic
  • Citrix
  • Oracle
  • PeopleSoft
  • SAP
  • Siebel
  • Lotus
  • and more...

Both hardware and software clustering are available for various Operating Systems.  For success stories, click here.