For many organizations, the e-commerce submodule facilitates interaction between the company and the outside world, and it is often the only way customers see the company’s products and services. In this regard, companies must be able to provide applications and Web services quickly, securely, and with high availability to potential customers. For some companies, downtime in the e-commerce submodule can cost millions of dollars, maybe on an hourly basis. Network designers should think about high availability techniques that can be used in the e-commerce design and they should take the following five components into consideration:
- Redundancy
- Technology
- People
- Processes
- Tools
Redundancy involves having hot spares and cold spares to eliminate any single points of failure. Redundancy is needed in several different areas of the e-commerce solution (both hardware and software), so if one component goes down, the service is not interrupted, at least for an acceptable period of time.
Some of the technologies that help improve high availability in the e-commerce submodule include:
- Stateful Switchover (SSO) – especially in firewall systems
- Non-Stop Forwarding (NSF)
- Server Load Balancing (SLB)
- Enhanced Object Tracking (EOT)
- IP SLA
- Performance Routing (PfR)/Optimized Edge Routing (OER)
- Fast routing convergence
The most overlooked resource for providing high availability in e-commerce submodules is well-trained engineers, who are critical in such environments. People resources should have the following skills:
- Reliable
- Communicative
- Consistent
- Skilled in creating documentation
- Skilled in troubleshooting
Processes are also very important for managing the e-commerce submodule and they should meet the PPDIOO lifecycle, the ITIL, or other framework goals. Some of the most important actions and tools that should be used in an e-commerce environment include:
- Performance monitoring
- Performance reporting
- Reporting on trends (observing anomalies from baselines)
- Observing traffic drops, packet loss, latency, and jitter
- Investigating case studies before launching an e-commerce solution, and perhaps implementing a prototype in a lab environment
- Documentation tools
Security design aspects are extremely important because of the e-commerce submodule’s exposure to the Internet and to public untrusted networks and because of its access by hundreds to millions of users on the Internet. The security components should be considered during the initial acquisition because they are key elements in the e-commerce design.
The e-commerce Access Layer (LAN) is logically divided into three tiers:
- Web tier
- Application tier
- Database tier
Server load balancing is deployed in the e-commerce submodule to support scalability and high availability. Its function is to redirect requests for service from clients across the active servers in the Web, application, and database tiers.
SLB can be deployed in the following modes:
- Router mode
- Bridge mode
- One-armed or two-armed modes
When connecting the e-commerce submodule to multiple ISPs, multiple design topologies can be implemented:
- One firewall per ISP
- Stateful failover with a common external prefix
- Distributed data centers
The four most important integrated designs for the e-commerce submodule are as follows:
- Base design
- Dual layer firewall design
- SLB one-armed mode with dual layer firewall design
- SLB one-armed mode with security contexts
Network designers should be aware of different methods for tuning the e-commerce submodule. The most common optimization mechanisms include:
- BGP tuning
- Enhanced Object Tracking
- Performance Routing
- DNS tuning and Global Server Load Balancer