< Day Day Up > |
The next step involves constructing a real network based on the logical network architecture. You can use several approaches to realize the network that functionally satisfies the logical architectural requirements. The multi-tier data center is vendor independent, and you can use the network equipment that best suits your environment. We briefly describe the original multi-tier data center implementation (secure multi-tier architectures), then we describe the multiswitch approach, and finally we describe the collapsed approach. Secure Multi-TierFIGURE 7-13 shows the overall structure of a classic multi-tier design. Figure 7-13. Secure Multi-TierThe advantages of this approach are simplicity and security. Clearly the only way to access the Data tier is through the application servers. There are no other possible network paths to access the Data tier. The drawbacks are limited flexibility and manageability. If an application running on the Web server needs to connect to an LDAP server or a database through a JDBC connection, a fundamental change to the architecture will be needed. As the number of tiers increases, so does the number of switches, which becomes a management issue. Multi-Level Architecture Using Many Small SwitchesFIGURE 7-14 shows the overall structure of a multi-level architecture that is composed of many small port density switches. Figure 7-14. Multi-Tier Data Center Architecture Using Many Small SwitchesThis approach has few advantages and many disadvantages. One advantage is that the entry cost is low. One can start from a very small deployment, procuring small eight-port multilayer switches and Layer 2 switches and increasing the tiers and servers to the point where the ingress links become a bottleneck or the port density of the small multilayer switches becomes an issue. Actual tested configurations leveraged Alteon 180 switches as the multilayer switches and Extreme Networks Summit 48i for the Layer 2 switches, which had gigabit uplinks and 10/100 ports for connections to the server. This architecture has the following disadvantages:
Flat Architecture Using Collapsed Large Chassis SwitchesThe flat network architecture using collapsed large chassis switches was found to be the best design for large-scale multi-tier deployments in availability, performance, and manageability. In the lab, we built two different network configurations. One configuration used Extreme Networks equipment (FIGURE 7-15), and the other used Foundry Networks equipment (FIGURE 7-16). Figure 7-15. Network Configuration with Extreme Networks EquipmentFigure 7-16. Sun ONE Network Configuration with Foundry Networks EquipmentThe Extreme Networks switch that we used has built-in load balancing, so there was no need for an external load-balancing device. The Foundry Networks products required use of a separate load-balancing switch. Physical Network ConnectivityThe physical wiring of the architecture is shown in FIGURE 7-17 and described in TABLE 7-3 Figure 7-17. Physical Network Connections and Addressing
|
< Day Day Up > |