Coyote Point Systems Equalizer, Installation And Administration Manual

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Chapter <$chapnum
128 Equalizer Installation and Administration Guide
1. O. Jacobsen and D. Lynch, Interop, Inc. March 1991.
name server A server that stores information about the domain name space.
NAT Network Address Translation.
NAT subsystem The Equalizer subsystem responsible for transferring connections to and from the back-end
servers.
netmask A bit mask used to select bits from an Internet address for subnet addressing. The mask is 32
bits long and selects the network portion of the Internet address and one or more bits of the
local portion. Also called address mask.
physical server A machine located on the internal network that provides services on specific IP addresses and
ports.
ping A program used to test reachability of destinations by sending them an ICMP echo request and
waiting for a reply.
port The abstraction used by Internet transport protocols to distinguish among multiple simultaneous
connections to a single destination host.
port number The number used to identify a service contact port, such as HTTP port 80.
reserved network A network consisting of “phony” IP addresses—IP addresses that are not registered and cannot
be made visible outside of the internal network.
server See physical server.
server address The IP address of a server on the internal interface. Multiple IP addresses can be aliased to a
single physical server.
server endpoint An IP address-port pair that identifies a physical or virtual server on the internal network to
which Equalizer can route connection requests.
server weight A value that indicates the relative proportion of connection requests that a particular back-end
server will receive.
site A cluster of servers under Equalizer control that is part of a geographic cluster.
static weight The server weight that an administrator assigns to a particular back-end server. During
operation, Equalizer dynamically adjusts the server weights, so a server’s weight at a particular
time might be different from the static weight originally set by the administrator.
sticky connection A connection where a particular client is connected to same server for subsequent requests
within a set period of time.
sticky timer A countdown timer that tracks periods of inactivity between a particular client and server.
traceroute A Unix network utility that displays the route a network packet takes to reach a specified host.
virtual cluster An endpoint that acts as the network-visible port for a set of hidden back-end servers.
virtual server address An IP address that is aliased to a physical server that has its own, separate IP address.
weight See server weight