Table of Contents

Product Overview
Key Features and Benefits

DNS Caching Nameserver Mode
HTTP Redirect Mode

Specifications
Ordering Information

Product Numbers

Cisco DistributedDirector

Product Overview

Cisco Systems DistributedDirector provides dynamic, transparent, scalable Internet traffic load distribution between multiple geographically dispersed servers. DistributedDirector is the only global Internet service scaling solution that leverages routing table information in the network infrastructure to make "network intelligent" load distribution decisions.

Cisco Systems DistributedDirector utilizes Cisco IOS software to transparently direct clients to closest available server, as determined by client-to-server topological proximity and/or client-to-server link latencies, thus localizing Internet traffic, maximizing end-to-end access performance, and reducing WAN bandwidth requirements and transmissions costs.

With DistributedDirector, users need only a single Domain Naming System (DNS) host name or URL-embedded host name for accessing a globally distributed set of servers, thus providing the appearance of a single virtual server. This eliminates the need for users to choose a server from a list of possible sites.

DistributedDirector enables transparent distribution of all common TCP/IP network services, such as Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Telnet, TN3270, and gopher.

The figure below illustrates the components of the DistributedDirector system. Note that DistributedDirector does not require any changes to client or server software or hardware.

The DistributedDirector system uses the Director Response Protocol (DRP), a simple UDP-based application developed by Cisco Systems, to query DRP agents in the field for Border Gateway Protocol (BGP) and Internal Gateway Protocol (IGP) "distance" metrics between DRP agents and clients.

To be a DRP agent, a border router (or peer, when BGP metrics are required) must run an appropriate Cisco IOS software release with the DRP agent software component included. DRP agent functionality is available in Cisco IOS Software Release 11.3T for the Cisco 2500 series, Cisco 2600 series, Cisco 3600 series, Cisco 4000 series, Cisco 7200 series, and Cisco 7500 series routers.

DRP Agents are required only when DRP metrics are used to redirect traffic.

DistributedDirector is configurable as an authoritative DNS caching nameserver and as an HTTP session redirector for a given host name or subdomain on a per-domain basis.

Key Features and Benefits

DNS Caching Nameserver Mode

In DNS caching nameserver mode, DistributedDirector acts as the primary DNS caching nameserver for a specific host name or subdomain. Using DRP, the Cisco DistributedDirector provides responses to DNS queries based on routing information contained in the network. DistributedDirector maps a host name to several possible IP addresses and uses the intelligence in the network infrastructure to dynamically determine the best IP-address-to-DNS-name binding for a given host name, based on client-to-server proximity and/or client-to-server link latency. In DNS caching nameserver mode, DistributedDirector works for all IP traffic. DistributedDirector returns an IP address of the best server to the client`s local DNS, independent of the particular Internet service requested at that IP address.

HTTP Redirect Mode

In HTTP redirect mode, the Cisco DistributedDirector provides HTTP session redirection services. In this mode, DistributedDirector accepts HTTP connections from clients, issues DRP queries to DRP-associated routers in the requested subdomain, sorts the DRP replies to determine the "best" web server, and sends to the client the HTTP status code "302 Temporarily Moved" with the new URL for the "best" server. The user is then transparently connected to the web server specified by this URL.

Specifications

For hardware specifications, please access Cisco on-line information at http://www.cisco.com.

For software specifications, please access Cisco on-line information at http://www.cisco.com.

Ordering Information

Product Numbers

DistributedDirector is available only as a software+hardware bundle as described below:

Posted: Wed Sep 27 05:13:17 PDT 2000
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