LANCOM Support Knowledgebase Document No. 1507.0713.2712.RHOO - V2.00

Using the client-binding function with LANCOM routers



Description:

The use of load balancing leads to problems for servers that use an IP address to identify a logged-on user. If a user is logged in to a website, for example, and the load balancer then uses a different Internet connection, the server will interpret this as a connection attempt by a new user who is not logged on. In the best case the user sees a new login dialog, but not the desired web page.

One possible workaround would be to use a firewall rule (policy-based routing, see Database 'SP Knowledgebase', View '03. Edit Documents\by Responsible, Status', Document 'Load balancer with policy-based routing') to direct the traffic to this server over a specific Internet connection. However, the full volume of the traffic to that particular server would then be limited to the bandwidth of a single connection. What's more, there is no way to establish a backup if the first connection should fail.


In contrast to this, client binding monitors not the individual TCP/IP sessions but the client that opened the Internet connection in the initial session. All subsequent sessions are directed through this Internet connection, which corresponds in principle to the policy-based routing mentioned above.

Exactly how this is done depends on the protocol, i.e. it transports only data of the same protocol type (e.g. HTTPS) over this Internet connection.

    Note:
    If you have an existing router configuration that operates load-balancing with policy-based routing (see Database 'SP Knowledgebase', View '03. Edit Documents\by Responsible, Status', Document 'Load balancer with policy-based routing') and you enable client binding after a firmware update to LCOS 9.10, then this is ineffective, because the policy-based routing directs the data traffic over a specific Internet connection. In this case, you must disable the policy-based routing in order to use the client binding.



Requirements:
  • LANCOM router with two or more functional Internet connections and operating with load balancing.

    For instructions on how to configure the load balancing in LANCOM routers, see the following Knowledge Base articles (Database 'SP Knowledgebase', View '03. Edit Documents\by Responsible, Status', Document 'Setting up load balancing for multiple Internet connections on a LANCOM router with an integrated DSL modem' or Database 'SP Knowledgebase', View '03. Edit Documents\by Responsible, Status', Document 'Setting up load balancing for multiple Internet connections on a LANCOM router without an integrated DSL modem').



Procedure:

1) Open the configuration of the LANCOM router in LANconfig and change to the menu IP-Router -> Routing -> Load-Balancing.



2) Open the existing load-balancing entry and enable client binding here.



3) In the lower section, you can adjust the behavior of the client binding.
  • The Binding minutes parameter specifies the time in minutes for the binding entries to remain valid for a client (default value: 30 minutes)
  • With the Balance seconds parameter you specify the time in seconds, following the start of the main session, during which the load balancer is free to distribute new sessions to other Internet connections (default value: 10 seconds).

    In order to prevent data from flowing via this main-session Internet connection when it could easily be transferred via parallel connections, a timer ensures that the load balancer distributes additional sessions between the available Internet connections for a specified period.


    After the timer expires, the client binding forces a new session over the original Internet connection and the timer is restarted. The server thus continues to recognize the login status for the user due to the current IP address.
  • Client binding is protocol-oriented. In the dialog Client-binding protocols you specify which protocols are used with client binding. Preset values are the protocols HTTP and HTTPS.


Catchwords: client; binding; load; balancing; balancer; http; https; banking
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