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System Administration Guide: IP Services     Oracle Solaris 11 Express 11/10
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Document Information


Part I TCP/IP Administration

1.  Planning an IPv4 Addressing Scheme (Tasks)

2.  Planning an IPv6 Addressing Scheme (Overview)

3.  Planning an IPv6 Network (Tasks)

4.  Configuring TCP/IP Network Services and IPv4 Addressing (Tasks)

5.  Enabling IPv6 on a Network (Tasks)

6.  Administering a TCP/IP Network (Tasks)

7.  Configuring IP Tunnels

8.  Troubleshooting Network Problems (Tasks)

9.  TCP/IP and IPv4 in Depth (Reference)

10.  IPv6 in Depth (Reference)


11.  About DHCP (Overview)

12.  Planning for DHCP Service (Tasks)

13.  Configuring the DHCP Service (Tasks)

14.  Administering DHCP (Tasks)

15.  Configuring and Administering the DHCP Client

16.  Troubleshooting DHCP (Reference)

17.  DHCP Commands and Files (Reference)

Part III IP Security

18.  IP Security Architecture (Overview)

19.  Configuring IPsec (Tasks)

20.  IP Security Architecture (Reference)

21.  Internet Key Exchange (Overview)

22.  Configuring IKE (Tasks)

23.  Internet Key Exchange (Reference)

24.  IP Filter in Oracle Solaris (Overview)

25.   IP Filter (Tasks)

Part IV Networking Performance

26.  Integrated Load Balancer Overview

27.  Configuration of Integrated Load Balancer Tasks

28.  Virtual Router Redundancy Protocol (Overview)

29.  VRRP Configuration (Tasks)

30.  Implementing Congestion Control

Network Congestion and Congestion Control

How to Implement TCP and SCTP Network Congestion Control

Part V IP Quality of Service (IPQoS)

31.  Introducing IPQoS (Overview)

32.  Planning for an IPQoS-Enabled Network (Tasks)

33.  Creating the IPQoS Configuration File (Tasks)

34.  Starting and Maintaining IPQoS (Tasks)

35.  Using Flow Accounting and Statistics Gathering (Tasks)

36.  IPQoS in Detail (Reference)



Network Congestion and Congestion Control

Network congestion occurs typically in the form of router buffer overflows, when nodes send more packets than the network can accommodate. Various algorithms have been developed that prevent of traffic congestion by setting controls on the sending systems. These algorithms are supported in Oracle Solaris and can be directly plugged in to the operating system.

The following table lists the supported algorithms with brief descriptions of each.

Oracle Solaris Name
Default algorithm in the Oracle Solaris system. Control mechanism includes sender's congestion window, slow start, and congestion avoidance.
One of the best known and simplest modifications of NewReno for high speed networks.
Currently the default algorithm in Linux 2.6. Changes congestion avoidance phase from linear window increase to a cubic function.
A classic delay-based algorithm that attempts to predict congestion without triggering actual loss.

In Oracle Solaris, congestion control is enabled by setting the following control-related TCP properties. Although these properties are listed for TCP, the control mechanism that is enabled by these properties also applies to SCTP traffic.

To set these properties, you use the ipadm set-prop command. You use either the += modifier to add algorithms or the -= modifier to remove algorithms.

How to Implement TCP and SCTP Network Congestion Control

  1. Become an administrator.

    For more information, see How to Obtain Administrative Rights in System Administration Guide: Security Services.

  2. Display the current settings of the protocol's congestion-control properties.
    # ipadm show-prop -p cong_enabled,cong_default tcp

    If you do not specify the properties, then all of the protocol properties will be displayed.

    The command displays both the current settings as well as the possible algorithms that you can assign to the properties.

  3. Set the congestion control properties of the protocol.
    # ipadm set-prop -p cong-ctrl-property+=algorithm tcp



    refers to either the cong_enabled property or the cong_default property.


    specifies the algorithm that you are setting for the property. You can specify any algorithm that is listed under the POSSIBLE field heading in the output of the ipadm show-prop command.

  4. (Optional) Remove an algorithm that is currently enabled.
    # ipadm set-prop -p cong-ctrl-property-=algorithm tcp

    Note - No sequence rules are followed when adding or removing algorithms. You can remove an algorithm before adding other algorithms to a property. However, the cong_default property must always have a defined algorithm.

  5. (Optional) Display the new settings of the congestion control properties.
    # ipadm show-prop -p cong_enabled,cong_default tcp

Example 30-1 Setting Algorithms for Congestion Control

This example changes the default algorithm of the TCP protocol from newreno to cubic. It also removes vegas from the list of enabled algorithms.

# ipadm show-prop -p cong_default,cong_enabled tcp
tcp    cong_default  rw    newreno          --           newreno   -
tcp    cong_enabled  rw    newreno,cubic,   --           newreno   newreno,cubic,
                           highspeed,                              highspeed,vegas

# ipadm set-prop -p cong_enabled-=vegas tcp
# ipadm set-prop -p cong_default=cubic tcp

# ipadm show-prop -p cong_default,confg_enabled tcp
tcp    cong_default  rw    cubic            --           newreno   -
tcp    cong_enabled  rw    newreno,cubic,   --           newreno   newreno,cubic,
                           highspeed                               highspeed,vegas