Hầu hết các bức tường lửa là CPU, chẳng hạn như một máy hoặc một máy x86 dựa trên SPARC. Bởi vì những hạn chế vi xử lý liên quan đến, số lượng thông qua một tường lửa có thể xử lý thường là hạn chế. Tốc độ xử lý, kích thước gói, cấu hình, và một số các số liệu khác là tất cả các yếu tố xác định những gì một bức tường lửa có thể làm, | Other Technologies Firewall Load Balancing Firewall Load Balancing FWLB has been developed to overcome some of the limitations of firewall technologies. Most firewalls are CPU-based such as a SPARC machine or an x86-based machine. Because of the processor limitations involved the amount of throughput a firewall can handle is often limited. Processor speed packet size configuration and several other metrics are all determining factors for what a firewall can do but generally they tend to max out at around 70 to 80 Mbps Megabits per second of throughput. Like SLB FWLB allows for the implementation of several firewalls sharing the load in a manner similar to SLB. Because of the nature of the traffic however the configuration and technology are different. Figure 1-4 shows a common FWLB configuration. Figure 1-4. A common FWLB configuration Global Server Load Balancing Global Server Load Balancing GSLB has the same basic concept as SLB but it distributes load to various locations as opposed to one location. SLB works on the 10 Chapter 1 Introduction to Server Load Balancing Local Area Network LAN while GSLB works on the Wide Area Network WAN . There are several ways to implement GSLB such as DNS-based and BGP-based Border Gateway Protocol . There are two main reasons to implement GSLB and to illustrate them we ll use an example of GLSB in action. Let s take the example of a site that has a presence in two different data centers one in San Jose California and one in New York City see Figure 1-5 1. GSLB brings content closer to the users. With cross-country latency at around 60 ms milliseconds or more it makes sense to bring the users as close to the servers as possible. For instance it would make sense to send a user in North Carolina to a server in New York City rather than to a server in San Jose California. 2. GSLB provides redundancy in case any site fails. There are many reasons why an entire data-center installation can go offline such as a fiber cut a power outage
