Integrated Load Balancer Overview
In Oracle Solaris, Integrated Load Balancer (ILB) provides Layer 3 and Layer 4 load-balancing
capabilities. ILB operates at the network (IP) and transport (TCP/UDP) layers for the Oracle Solaris
operating system installed on SPARC-based and x86-based systems. ILB can be used to improve
reliability and scalability, and to minimize the response time of network services.
How Integrated Load Balancer Works
ILB intercepts incoming requests from clients, decides which back-end server should handle the
requests based on load-balancing rules, and then forwards the requests to the selected server. ILB
can also be used as a router for the back-end server. ILB performs optional health checks and
provides the data for the load-balancing algorithms to verify whether the selected server can handle
the incoming requests.
Features of ILB
The key features of ILB include the following:
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Supports stateless Direct Server Return (DSR) and Network Address Translation (NAT) modes of
operation for IPv4 and IPv6.
For information about DSR and NAT modes of operation, see ILB Operation Modes.
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Assists traffic and load distribution and server selection by using a set of algorithms for
the two modes of operation.
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Enables ILB administration through a command-line interface (CLI).
For information about configuring ILB by using CLI, see Configuring ILB by Using the Command-Line Interface.
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Provides server monitoring capabilities through health checks.
For information about server monitoring capabilities, see Monitoring Health Checks in ILB.
The following table lists and describes the features of ILB that are available for different
modes of operation.
Table 3 ILB Features
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Enables clients to ping virtual IP (VIP) addresses
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ILB responds to ICMP echo requests from clients to VIP addresses.
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Both DSR and NAT modes
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Enables you to add and remove servers from a server group without interrupting service
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ILB dynamically adds or removes servers from server group.
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NAT mode
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Enables you to configure session persistence ("stickiness")
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ILB enables you to configure session persistence to your applications to send the connections
or packets from a client to the same back-end server. ILB enables you to configure session
persistence (that is, source address persistence) for a virtual service by using the
-p option and specifying the pmask option in the
ilbadm create-rule command. For more information, see Creating an ILB Rule.
|
Both DSR and NAT modes
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Enables you to perform connection draining
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ILB prevents new connections from being sent to a server that is disabled. This feature is
useful for shutting down a server without disrupting the active connections or sessions. The
existing connections to the server continue to function. After all the connections to that server
are terminated, the server can be shut down for maintenance. After the server is ready to handle
requests, it is enabled so that the load balancer can forward new connections to it.
|
NAT mode
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Enables load-balancing of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
ports
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ILB balances the load on all ports on a given IP address across different sets of servers
without requiring you to set up explicit rules for each port.
|
Both DSR and NAT modes
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Enables you to specify independent ports for virtual services within the same server
group
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ILB enables you to specify different destination ports for different servers in the same
server group.
|
NAT mode
|
Enables you to load-balance a simple port range
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ILB balances loads on a range of ports on the VIP to a given server group. For convenience,
you can conserve IP addresses by load-balancing different port ranges on the same VIP to different
sets of back-end servers. Also, when session persistence is enabled for NAT mode, ILB sends requests
from the same client IP address for different ports in the range to the same back-end server.
|
Both DSR an NAT modes
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Enables port range shifting and collapsing
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Port range shifting and collapsing depend on the port range of a server in a load-balancing
rule. If the port range of a server is different from the VIP port range, port shifting is
automatically implemented. If the server port range is a single port, then port collapsing is
implemented.
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NAT mode
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For information about the ILB components, operating modes, algorithms, and how ILB works, see
Overview of an Integrated Load Balancer. For more
information about configuring and managing ILB, see Configuring and Managing the Integrated Load Balancer and Configuring ILB for High Availability.