Assure Transaction Completion Around the Globe
For globally deployed web-enabled applications, one critical data center requirement is to guarantee that each transaction is executed to completion. To successfully accomplish this, a user’s transaction must always be directed to an available site that knows the user’s information and the status of the transaction.
By using application delivery controllers (ADCs), issues like business fluctuations (bursts and peaks) and potential application or network failures can be averted. Users are directed to the site which delivers the best experience.
Global server load balancing solutions use domain name system (DNS) redirection to locate an available site for transaction processing. However, DNS redirection has limitations in multiple data center environments and DNS-only solutions cannot ensure transaction continuity and fast response time.
Best Site Selection is Key
Radware’s global re-direction is the only solution in the market to assure both transaction completion and fast response times. This is accomplished by fully optimizing globally distributed server resources across multiple data centers based on application/transaction persistency, content availability, load and proximity. Provided as an
AppDirector™ option, this software module includes the fundamental core ADC capability required for multiple data center environments.
It is also critical to provide accurate load and proximity reporting, a range of re-direction methods and fast site failover in multiple data center environments. AppDirector’s global re-direction solution addresses these concerns.
- Accurate load and proximity reporting – Both the end user’s proximity to the data centers and the data centers’ load and availability are calculated in real time using patented technology. AppDirector devices installed in different sites frequently exchange load and proximity information ensuring that site selection is based on up-to-date and accurate information.
- Wide range of redirection methods – These methods provide globally distributed data centers providing high availability and optimized delivery for any IP-based service/application. The methods include any combination of
- Client NAT
- DNS
- Global Triangulation®
- HTTP redirection
- RTSP redirection
These redirection methods also correct inferior site selection decisions which, due to DNS caching or due to lack of persistency identifiers in DNS requests, may interrupt transaction completion.
- Fast site failover – AppDirector’s unique ability of announcing Virtual IP (VIP) reachability provides fast and transparent service continuity (without requiring additional DNS query) in case of site failure. AppDirector uses common routing protocols such as BGP, OSPF and RIP.
Three-Tier Global Architectural Approach
Radware’s three-tier architectural approach to global re-direction lets enterprises create a true global network capable of delivering a wide range of applications while ensuring maximum uptime and optimized service delivery of all hosted applications for globally dispersed users.
DNS Resolution: AppDirector, acting as a DNS server, communicates with the client’s DNS server to determine the site that best answers the client’s request based on load and proximity.
Global Application Re-direction: AppDirector communicates with the client to determine the best site based on load, persistency and content. AppDirector uses redirection methods such as Client NAT, DNS, Global Triangulation, HTTP and RTSP to correct inferior site selection made by the DNS server.
Local Server Selection: AppDirector selects the best local server for the client’s request based on persistency content, server load and availability.