NetScaler Networking Deployment
说起NetScaler，一直没有时间详细的研究，今天有空，研究了下NetScaler的网络部署。
其实，很简单，要了解怎么来部署NetScaler的网络结构，需要了解NetScaler的工作原理，这里大致介绍一下：
Citrix NetScaler is a Web application delivery appliance that makes
applications run five times better. Available as a separate hardware network
device or as a virtualized appliance, NetScaler optimizes application
availability through advanced L4-7 load balancing and traffic management,
accelerates performance, increases security with an integrated application
firewall and substantially lowers costs by increasing Web server efficiency.
主要作用就是Web加速，SSL ×××的功能，load balancing，access gateway，application
firewall等可以了解下。
弄清楚了它的工作原理就很清楚了。它是一个访问网关，转发器。
部署方式主要由两类四种方式，针对四种不同的网络结构。
Two-Arm Mode ,Multiple Subnets
Two-Arm Mode,Transparent Mode
One-Arm Mode,Single Subnet
One-Arm Mode,Multiple Subnets
看图，能看个大概。解释下图中的几个名词：
One-Arm：单臂
Two-Arm：双臂
NSIP：NetScaler IP Address，NetScaler的管理口地址
VIP：Virtual IP Address，对外提供服务的地址
SNIP：Subnet IP Address，连接内网服务器的地址
MIP:Mapped IP Address，连接内网服务器的地址
GSLBIP:Global Server Load Balancing IP
Address，多数据中心做负载均衡时使用的地址
