Load Balancing FAQ

What editions of NetScaler does SoftLayer offer?

Standard and Platinum editions for NetScaler VPX, Enterprise and Platinum Edition for MPX.

Does the Softlayer NetScaler offering include SSL VPN functionality?

Yes, this feature is known as NetScaler Gateway™ and is included in all editions.  For more information regarding this feature please visit Citrix website: http://support.citrix.com/proddocs/topic/netscaler-getting-started-map-93/ns-hrdwre-ns-editions-con.html

Why am I getting 502 Gateway errors when using SSL offloading?

This is normally caused by the outgoing port of the load balancer being set to port 443.  If load balancing is enabled outbound traffic, to your server, will need to be set to the non-SSL port of your server.  This is typically port 80 for HTTP.

Can I have multiple SSL certificates on a single load balancer?

This is possible in certain configurations.  The general rule is one SSL certificate per Virtual IP (VIP).  A local load balancer only supports a single VIP but this can be increased on our dedicated and enterprise load balancers.

 

What is a virtual port?

A virtual port in a SoftLayer load balancer is simply the port you wish to run the service on.  An example would be port 80 for HTTP.

What method of load balancing is used for Local and Dedicated load balancers?

Our load balancers are proxy based.

How long does it take to install a load balancer?

Load balancers should be installed and available for your configure about five minutes after purchase.

Can I add SSL offloading to an existing load balancer?

This is currently not supported.  A new order for a load balancer with SSL offloading will need to be placed.

What services can be load balanced?

The most common ones are ports like HTTP (80), HTTPS (443), FTP (21), DNS (53), POP3 (110), and SMTP (25). Any service can be load balanced, however.

How do I downgrade my local load balancer?

This option is only available by opening a ticket.

What balancing methods are available with a Load Balancer?

SoftLayer offers multiple balancing methods, including both single and hybrid methods.  Refer to the table below for more information about each load balance method we currently offer.

Load Balance Method

Description

Consistent Hash IP

  • Maps client requests to real servers by hashing the source IPs of the request.
  • Client/Server relationships are maintained across ports.

Insert Cookie

  • Inserts a tracking cookie into the request.  Session data contained within the cookie is used with subsequent request to send traffic back to the same real server.
  • Persistence is hard-coded on a per-session basis.
  • Cookie expires after the client’s browser is closed.
  • Requires that the client accepts cookies to be effective.

Least Connections

  • The real server with the fewest number of active connections gets first priority.
  • Algorithm requires a difference of 10 connections, which may skew results for customers

Persistent IP

  • Ties the source IP of the requester to the real server that processes the request by a hash of all 4 octets of the requesting IP address.
  • Persists for 60 minutes

Round Robin

  • Each new request is assigned to the next real server in the rotation.
  • Balanced distribution occurs over large samples, though small samples may display a disproportionate balance.

Shortest Response

  • Server with the shortest response time receives the request.
  • As load and response time increases, slower servers begin to field fewer requests.

Round Robin with Persistent IP

  • Each new request is assigned to the next real server in the rotation.
  • Requester’s IP address is tied to the real server, resulting in subsequent requests from the IP to be assigned to the same real server.

Round Robin with Insert Cookie

  • Each new request is assigned to the next real server in the rotation.
  • The load balancer inserts a cookie into the request and uses the session information from the cookie to direct traffic to the same real server for subsequent requests.

Least Connections with Persistent IP

  • Each new request is assigned to the real server with the least number of active connections at the moment.
  • Requester’s IP address is tied to the real server, resulting in subsequent requests from the IP to be assigned to the same real server.

Least Connections with Insert Cookie

  • Each new request is assigned to the real server with the least number of active connections at the moment.
  • The load balancer inserts a cookie into the request and uses the session information from the cookie to direct traffic to the same real server for subsequent requests.

Shortest Response with Persistent IP

  • Each new request is assigned to the real server with the shortest response time.
  • Requester’s IP address is tied to the real server, resulting in subsequent requests from the IP to be assigned to the same real server.

Shortest Response with Insert Cookie

  • Each new request is assigned to the real server with the shortest response time.
  • The load balancer inserts a cookie into the request and uses the session information from the cookie to direct traffic to the same real server for subsequent requests.
Is it possible to load balance SSL encrypted traffic with session stickiness?

This is possible but only with a persistent balancing method.  Other methods are not supported since the traffic is encrypted.

What is Citrix Netscaler?

Citrix NetScaler is an application delivery controller that makes applications five times better by accelerating performance, ensuring application availability and protection and substantially lowering operational costs. We offer NetScaler on the VPX platform. Choose the best Citrix NetScaler edition that meets your application requirements, and deploy it on the right dedicated system for your performance needs. Cost effectively deploy the same L4 load balancing, L7 traffic management, TCP and SSL offload, content caching and compression and web application firewall functionality used by the largest websites in the world. To learn more about Citrix Netscaler, refer to the NetScaler page on the Citrix website.

Does NetScaler support IPv6?

Yes. Both IPv6 and IPv4 are supported on the SoftLayer public network.

Will the NetScaler load balance traffic on the private network?

Yes, the NetScaler is the only SoftLayer load balancing product that extends into the private network.

Can the Netscaler be configured to report the client's source IP address instead of the source IP of the Netscaler appliance?

Yes, the Use Source IP (USIP) parameter can be set to "YES" within the NetScaler Advanced Management Interface to allow reporting of the client's source IP instead of that of the NetScaler.

Enabling the USIP address mode on the appliance adds flexibility to the appliance to use the client IP address, available in the IP header, when communicating to the server. By enabling this mode, the appliance opens server connections with the client IP address and also factors the client IP address in connection reuse. Therefore, this mode facilitates limited reuse per client based on client IP address.

What editions of the dedicated Hardware NetScaler MPX does SoftLayer offer?

The NetScaler MPX 11515, 11520, 11530, 11540, 11542. Please contact Sales for pricing information and to order.

What are the various ports used to exchange the HA-related information between the nodes in an HA configuration?

Port 3010, for synchronization and command propagation. UDP Port 3003, to exchange heartbeat packets.

Are NetScaler VPX bandwidth/throughput limits for inbound only traffic, or both inbound and outbound traffic?

NetScaler VPX bandwidth limits are enforced for traffic inbound to the NetScaler only, regardless of whether this is request traffic or response traffic. This indicates that a NetScaler VPX-1000 (for example) can process both 1 Gbps of inbound traffic and 1 Gbps of outbound traffic simultaneously.