Netscaler Introduction

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Transcript Netscaler Introduction

Netscaler Introduction

D’Sunte Wilson 1

Day 1

       Understanding the NetScaler Accessing a Citrix NetScaler Configuring a NetScaler for the First Time Understanding Common Network Topologies Configuring System Management Settings Load Balancing Traffic on a NetScaler Accelerating Load Balanced Traffic by Using Compression 2

Understanding the NetScaler   The Citrix NetScaler product is an application switch that performs application-specific traffic analysis to intelligently distribute, optimize, and secure Layer 4-Layer 7 (L4-L7) network traffic for web applications.

It has switching feature. When deployed in front of application servers, a NetScaler ensures optimal distribution of traffic by the way in which it directs client requests.


Understanding the NetScaler    NetScaler security and protection features protect web applications from application layer attacks. A NetScaler allows legitimate client requests and can block malicious requests. It provides built-in defenses against denial-of service (DoS) attacks and supports features that protect applications against legitimate surges in application traffic that would otherwise overwhelm the servers.


Understanding the NetScaler  Optimization features offload resource intensive operations such as Secure Sockets Layer (SSL) processing, data compression, client keep-alive, TCP buffering, and the caching of static and dynamic content from servers.


Understanding the NetScaler

   A NetScaler resides between the clients and the servers, so that client requests and server responses pass through it. In a typical installation, virtual servers (vservers) configured on the NetScaler provide connection points that clients use to access the applications behind the NetScaler. In this case, the NetScaler owns public IP addresses that are associated with its vservers, while the real servers are isolated in a private network.


Understanding the NetScaler

   A NetScaler logically residing between clients and servers can be deployed in either of two physical modes: inline and one-arm. In inline mode, multiple network interfaces are connected to different Ethernet segments, and the NetScaler is placed between the clients and the servers. The NetScaler has a separate network interface to each client network and a separate network interface to each server network. 7

Understanding the NetScaler

Inline 8

Understanding the NetScaler

   In one-arm mode, only one network interface of the NetScaler is connected to an Ethernet segment. The NetScaler in this case does not isolate the client and server sides of the network, but provides access to applications through configured vservers. One-arm mode can simplify network changes needed for NetScaler installation in some environments.


Understanding the NetScaler

  A NetScaler functioning as an L2 device is said to operate in L2 mode. In L2 mode, the NetScaler forwards packets between network interfaces when all of the following conditions are met: ◦ The packets are destined to another device's media access control (MAC) address.

◦ The destination MAC address is on a different network interface.

◦ The network interface is a member of the same virtual LAN (VLAN).


Understanding the NetScaler

   A NetScaler can function as a packet forwarding device, and this mode of operation is called L3 mode. With L3 mode enabled, the NetScaler forwards any received unicast packets that are destined for an IP address that it does not have internally configured, if there is a route to the destination. A NetScaler can also route packets between VLANs.


Understanding the NetScaler

  A NetScaler is usually deployed in front of a server farm and functions as a transparent TCP proxy between clients and servers, without requiring any client side configuration. This basic mode of operation is called Request Switching technology and is the core of NetScaler functionality.


Understanding the NetScaler

     

NetScaler IP address (NSIP) Mapped IP address (MIP) Virtual server IP address (VIP) Subnet IP address (SNIP) IP Set Net Profile


Understanding the NetScaler


Understanding the NetScaler

   In the absence of a vserver, when a NetScaler receives a request, it transparently forwards the request to the server. This is called the transparent mode of operation. When operating in transparent mode, a NetScaler translates the source IP addresses of incoming client requests to the MIP or SNIP but does not change the destination IP address.


Understanding the NetScaler


Understanding the NetScaler

Load balancing 17

Understanding the NetScaler

   A vserver is a named NetScaler entity that external clients can use to access applications hosted on the servers. It is represented by an alphanumeric name, virtual IP address (VIP), port, and protocol. The name of the vserver is only of local significance and is designed to make the vserver easier to identify.


Understanding the NetScaler


Understanding the NetScaler

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Load balancing virtual server Cache redirection virtual server Content switching virtual server Virtual private network (VPN) virtual server SSL virtual server


Understanding the NetScaler

   A policy defines specific details of traffic filtering and management on a NetScaler. It consists of two parts: the expression and the action. The expression defines the types of requests that the policy matches.


Accessing a Citrix NetScaler     A NetScaler® appliance has both a command line interface (CLI) and a graphical user interface (GUI). The GUI includes a configuration utility for configuring the appliance and a statistical utility, called Dashboard. For initial access, all NetScaler appliances ship with the default NetScaler IP address (NSIP) of and default subnet mask of You can assign a new NSIP and an associated subnet mask during initial configuration.


Configuring a NetScaler for the First Time       Your new NetScaler is preconfigured with a default IP address (the NSIP) and associated subnet mask for management access. The default NSIP is and the subnet mask (netmask) is You can change these values to fit the addressing scheme for your network. For your initial configuration, you must also specify at least one SNIP or MIP. Before saving your new configuration, you should change the administrator password.

If you are setting up two NetScaler appliances as a high availability pair, you configure one as primary and the other as secondary.


Understanding Common Network Topologies  In a two-arm topology, one network interface is connected to the client network and another network interface is connected to the server network, ensuring that all traffic flows through the NetScaler.


Understanding Common Network Topologies Topology Diagram for Two-Arm Mode, Multiple Subnets 25

Understanding Common Network Topologies Topology Diagram for Two-Arm, Transparent Mode 26

Understanding Common Network Topologies Topology Diagram for One-Arm Mode, Single Subnet 27

Understanding Common Network Topologies Topology Diagram for One-Arm Mode, Multiple Subnets 28