Overview: Network Dispatcher for IBM WebSphere Edge Server V2.0

Network Dispatcher is an administration and configuration tool that provides dynamic load balancing, scalability, and high availability for servers on the Internet or on your Intranet.

Highlights of Version 2.0 include:

  • AIX v5.1 support for all components of Network Dispatcher
  • Red Hat Linux v7.1 support for all components of Network Dispatcher
  • Red Hat Linux and Solaris National Language support (NLS) for all components of Network Dispatcher
  • SuSE Linux v7.1 support for all components of Network Dispatcher
  • New Chinese NLS Standard support for all components of Network Dispatcher
  • Consultant for Cisco CSS Switches component - in collaboration with Cisco and their Content Distribution Network (CDN) a new component, Cisco Consultant, has been developed for Network Dispatcher. This component, which was introduced as a standalone preview in June 2001, provides the existing Network Dispatcher manager and advisor to generate weights for Cisco's CSS to assist in load balancing.
  • Site Selector - this new component replaces the Interactive Session Support (ISS) component in prior releases of Network Dispatcher. Site Selector provides similar function to ISS, but has reduced the number of manual steps needed to set up a typical DNS load-balancing configuration.
  • Mailbox Locator - this new component was formerly a feature within the Content Based Routing component. It load balances across IMAP and POP3 mail servers. Separating CBR into two components removes the limitation that "CBR for IMAP/POP3" (Mailbox Locator) and "CBR for HTTP/HTTPS" (CBR with Caching Proxy) cannot be run on the same machine.
  • Network Address Translation (NAT) and Network Address Port Translation (NAPT) support - on Dispatcher, this new feature eliminates the limitation for backend servers to be located on a locally-attached network. It also enables Dispatcher to load balance the client's TCP requests to multiple server daemons running on the same physical machine.
    • NAT allows you to configure multiple server daemons to respond to requests to different IP addresses.
    • NAPT allows you to configure multiple server daemons to listen on different port numbers.
  • Dispatcher's content-based routing feature (using content rule and SSL session ID affinity) - on the Dispatcher component, this new feature allows you to perform content-based routing for HTTP traffic, without using Caching Proxy.
  • Passive Cookie affinity - on the Dispatcher and CBR components, this new feature allows you to load-balance Web traffic with affinity to the same server based upon self-identifying cookies generated by the servers.
  • URI Affinity (load balancing to caching proxies) - on the Dispatcher and CBR components, this new feature allows you to load-balance Web traffic to caching-proxy servers in a manner that effectively increases the size of the cache.
  • Cluster (or Site Name) Specific Proportions - you can now set the proportion of importance for determining load-balancing decisions on a per cluster (or site name) basis on all Network Dispatcher components.
  • Enhanced User Exits - Network Dispatcher now provides several additional user exits that trigger customer scripts giving you enhanced event detection and handling.
  • Server Partitioning - provides the ability to partition one physical server into several logical servers. For example, this allows you to check a particular service on the machine to detect if a servlet engine or a database request is running faster, or not running at all. This enhancement provides you with the ability to distribute load based on more granular service-specific workload.
  • HTTP Advisor Request/Response (URL) Option - you can assess the health of individual services within a server. For each logical server under the HTTP port, you can specify a unique client HTTP URL string, specific for the service that you want to query on the server.
  • Cluster (or Site) Specific Advisors - you can now start different advisors running on different clusters (or sites), on the same port.
  • DB2 Advisor - this is a new advisor that allows Dispatcher to communicate with the DB2 servers.
  • Denial of Service (DoS) Attack Detection - Dispatcher provides the ability to detect potential denial of service attacks and notify administrators with an alert.
  • Installation of Network Dispatcher components has been streamlined to reduce file redundancy resulting in the reduction of the installation package size.

The five major components of Network Dispatcher are:

  • Dispatcher - provides load balancing for TCP and UDP applications. Dispatcher balances the load on servers within a local area network or wide area network using several weights and measurements that are dynamically set.

    New in v2.0, content-based routing (without Caching Proxy) is available on the Dispatcher component to load balance incoming client requests, based on Web page content using specified rule types, to HTTP servers.

  • Content Based Routing (CBR) - works with Caching Proxy to load balance incoming client requests, based on Web page content using specified rule types, to HTTP or HTTPS servers.

  • Mailbox Locator - For IMAP and POP3 protocols, Mailbox Locator is a proxy that chooses an appropriate mail server based on user ID and password.

  • Site Selector - balances the load on servers within a wide area network (WAN) using measurements and weights that are gathered from the Metric Server component running on those servers.

  • Cisco Consultant - uses Network Dispatcher technology to provide real-time load balancing information to the Cisco Content Services Switch.

Visit the Websphere Edge Server web site for the latest details on using this product to maximize the performance of your servers. Configuration examples and scenarios are included, as well as news, case studies, and support information.

For information on how to perform Network Dispatcher tasks, click How do I? in the navigation area to the left; for reference information, click Reference. To find information by keyword, select the Index tab.