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Getting Started with Citrix NetScaler
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Deploy a Citrix NetScaler VPX instance
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Install a Citrix NetScaler VPX instance on Microsoft Hyper-V servers
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Install a NetScaler VPX instance on Linux-KVM platform
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Prerequisites for Installing NetScaler VPX Virtual Appliances on Linux-KVM Platform
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Provisioning the NetScaler Virtual Appliance by using OpenStack
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Provisioning the NetScaler Virtual Appliance by using the Virtual Machine Manager
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Configuring NetScaler Virtual Appliances to Use SR-IOV Network Interface
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Configuring NetScaler Virtual Appliances to use PCI Passthrough Network Interface
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Provisioning the NetScaler Virtual Appliance by using the virsh Program
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Deploying NetScaler VPX Instances on AWS
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Upgrade and downgrade a NetScaler appliance
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Overriding Static Proximity Behavior by Configuring Preferred Locations
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Example of a Complete Parent-Child Configuration Using the Metrics Exchange Protocol
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Configuring Global Server Load Balancing for DNS Queries with NAPTR records
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Using the EDNS0 Client Subnet Option for Global Server Load Balancing
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Persistence and persistent connections
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Advanced load balancing settings
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Gradually stepping up the load on a new service with virtual server–level slow start
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Protect applications on protected servers against traffic surges
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Use source IP address of the client when connecting to the server
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Set a limit on number of requests per connection to the server
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Configure automatic state transition based on percentage health of bound services
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Use case 2: Configure rule based persistence based on a name-value pair in a TCP byte stream
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Use case 3: Configure load balancing in direct server return mode
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Use case 6: Configure load balancing in DSR mode for IPv6 networks by using the TOS field
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Use case 7: Configure load balancing in DSR mode by using IP Over IP
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Use case 10: Load balancing of intrusion detection system servers
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Use case 11: Isolating network traffic using listen policies
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Use case 14: ShareFile wizard for load balancing Citrix ShareFile
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Configuring a CloudBridge Connector Tunnel between two Datacenters
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Configuring CloudBridge Connector between Datacenter and AWS Cloud
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Configuring a CloudBridge Connector Tunnel Between a Datacenter and Azure Cloud
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Configuring CloudBridge Connector Tunnel between Datacenter and SoftLayer Enterprise Cloud
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Configuring a CloudBridge Connector Tunnel Between a NetScaler Appliance and Cisco IOS Device
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CloudBridge Connector Tunnel Diagnostics and Troubleshooting
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Using the EDNS0 Client Subnet Option for Global Server Load Balancing
EDNS Client Subnet (ECS) is a DNS header extension that provides the client subnet details. You can use these details to improve the accuracy of NetScaler Global Server Load Balancing (GSLB) by using the client network location rather than the DNS resolver location to determine the topological closeness of the client.
Note
NetScaler supports only EDNS0.
Important:
Make sure that the LDNS in your deployment supports EDNS0 Client Subnet so that the incoming DNS queries contains the EDNS0 Client Subnet option and the NetScaler appliance uses the ECS address while processing the DNS query.
In a typical GSLB deployment, when you use proximity-based load balancing methods like static proximity or dynamic round-trip time (RTT), the NetScaler appliance uses the local DNS (LDNS) IP address for determining the topological closeness of the client and performs GSLB accordingly. But when a centralized DNS resolver, such as Google DNS or OpenDNS, is involved in the deployment, the NetScaler appliance sends the DNS request to a datacenter close to the centralized DNS resolver, which might not be close to the client. For example, in a typical NetScaler GSLB deployment using the static proximity load balancing method, an end-user request from Japan is sent to a datacenter in Japan and an end user request from California is sent to a datacenter in California. But if a centralized DNS resolver is involved, the NetScaler appliance might send a request from Japan to a datacenter in California.
You can use the ECS option in deployments that include the NetScaler appliance configured as Authoritative DNS (ADNS) server for a GSLB domain. If you use static proximity as the load balancing method, you can use the IP subnet in the EDNS header instead of the LDNS IP address to determine the geographical proximity of the client. In the case of proxy mode deployment, the NetScaler appliance forwards an ECS-enabled DNS query as-is to the back-end servers, and the appliance does not cache ECS-enabled DNS responses.
Note
The ECS option is not applicable for all other deployment modes, such as ADNS mode for non-GSLB domains, resolver mode, and forwarder mode. In all these modes, the ECS option is ignored by the NetScaler appliance. Also, by default, ECS is disabled for GSLB deployment.
To enable EDNS0 Client Subnet option by using the command line interface:
At the command prompt, type:
set gslb vserver <vserver_name> **-ECS ENABLED
set gslb vserver vserver-GSLB-1 -ECS ENABLED
Address validation
You can configure a GSLB virtual server to verify that the address returned by the EDNS0 Client Subnet (ECS) option of the DNS query is not a private or an unroutable IP address. With address validation enabled, the NetScaler appliance ignores the ECS address in the DNS query if it is listed in the following table, and instead uses the LDNS IP address for global server load balancing.
Note
By default, address validation is disabled.
Address Type | Address | Description |
IPV4 | 10.0.0.0/8 | For private use |
172.16.0.0/12 | For private use | |
192.168.0.0/16 | For private use | |
0.0.0.0/8 | Refers to the host on the network | |
100.64.0.0/10 | Shared address space | |
127.0.0.0/8 | Loopback address | |
169.254.0.0/16 | Link Local IPv4 address as defined in RFC 3927 | |
192.0.0.0/24 | Used for IETF protocol assignments, includes the private space 192.168.0.0/16 | |
192.0.2.0/24 | Used for documentation purposes | |
192.88.99.0/24 | Used for 6to4 Relay Anycast | |
198.18.0.0/15 | Used in Device benchmark testing | |
198.51.100.0/24 | Used for documentation purposes | |
203.0.113.0/24 | Used for documentation purposes | |
240.0.0.0/4 | Used as reserved | |
255.255.255.255/32 | Used for broadcast | |
IPv6 | ::1/128 | loopback address |
::/128 | unspecified address | |
::ffff:0:0/96 | IPv4-mapped address | |
100::/64 | discard-only address block | |
2001::/23 | Used for IETF protocol assignments | |
2001::/32 | TEREDO | |
2001:2::/48 | Used for benchmarking | |
2001:db8::/32 | Used for documentation purposes | |
2001:10::/28 | ORCHID | |
2002::/16 | Used for 6to4 Relay Anycast | |
fc00::/7 | Unique-local | |
fe80::/10 | Link-local Unicast addresses |
To enable address validation by using the command line interface
At the command prompt, type:
set gslb vserver <vserver_name> -ecsAddressValidation ENABLED
set gslb vserver vserver-GSLB-1 -ecsAddressValidation ENABLED
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