JavaScript is required to for searching.
Skip Navigation Links
Exit Print View
Oracle Solaris Administration: IP Services     Oracle Solaris 11 Information Library
search filter icon
search icon

Document Information


Part I TCP/IP Administration

1.  Planning the Network Deployment

2.  Considerations When Using IPv6 Addresses

3.  Configuring an IPv4 Network

4.  Enabling IPv6 on the Network

5.  Administering a TCP/IP Network

6.  Configuring IP Tunnels

7.  Troubleshooting Network Problems

8.  IPv4 Reference

9.  IPv6 Reference


10.  About DHCP (Overview)

11.  Administering the ISC DHCP Service

12.  Configuring and Administering the DHCP Client

13.  DHCP Commands and Files (Reference)

Part III IP Security

14.  IP Security Architecture (Overview)

15.  Configuring IPsec (Tasks)

16.  IP Security Architecture (Reference)

17.  Internet Key Exchange (Overview)

18.  Configuring IKE (Tasks)

19.  Internet Key Exchange (Reference)

20.  IP Filter in Oracle Solaris (Overview)

21.  IP Filter (Tasks)

Part IV Networking Performance

22.  Integrated Load Balancer Overview

23.  Configuration of Integrated Load Balancer (Tasks)

24.  Virtual Router Redundancy Protocol (Overview)

25.  VRRP Configuration (Tasks)

26.  Implementing Congestion Control

Network Congestion and Congestion Control

How to Implement TCP and SCTP Network Congestion Control

Part V IP Quality of Service (IPQoS)

27.  Introducing IPQoS (Overview)

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

29.  Creating the IPQoS Configuration File (Tasks)

30.  Starting and Maintaining IPQoS (Tasks)

31.  Using Flow Accounting and Statistics Gathering (Tasks)

32.  IPQoS in Detail (Reference)



Network Congestion and Congestion Control

Network congestion typically occurs in the form of router buffer overflows, when nodes send more packets than the network can accommodate. Various algorithms prevent traffic congestion through establishing controls on the sending systems. These algorithms are supported in Oracle Solaris and can be easily added or directly plugged in to the operating system.

The following table lists and describes the supported algorithms.

Oracle Solaris Name
Default algorithm in Oracle Solaris. 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 the congestion avoidance phase from linear window increase to a cubic function.
A classic delay-based algorithm that attempts to predict congestion without triggering actual packet 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 an algorithm or the -= modifier to remove an algorithm.

How to Implement TCP and SCTP Network Congestion Control

  1. Become an administrator.

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

  2. Display the current values of the TCP 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 properties are displayed.

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

  3. Set the congestion control properties of the TCP 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 you add or remove 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 values of the congestion control properties.
    # ipadm show-prop -p cong_enabled,cong_default tcp

Example 26-1 Setting Algorithms for Congestion Control

This example changes the default algorithm for 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