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Oracle Solaris Administration: IP Services     Oracle Solaris 11 Information Library
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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

Part V IP Quality of Service (IPQoS)

27.  Introducing IPQoS (Overview)

IPQoS Basics

What Are Differentiated Services?

IPQoS Features

Where to Get More Information About Quality-of-Service Theory and Practice

Books About Quality of Service

Requests for Comments (RFCs) About Quality of Service

Web Sites With Quality-of-Service Information

IPQoS Man Pages

Providing Quality of Service With IPQoS

Implementing Service-Level Agreements

Assuring Quality of Service for an Individual Organization

Introducing the Quality-of-Service Policy

Improving Network Efficiency With IPQoS

How Bandwidth Affects Network Traffic

Using Classes of Service to Prioritize Traffic

Differentiated Services Model

Classifier (ipgpc) Overview

IPQoS Classes

IPQoS Filters

Meter (tokenmt and tswtclmt) Overview

Marker (dscpmk and dlcosmk) Overview

Flow Accounting (flowacct) Overview

How Traffic Flows Through the IPQoS Modules

Traffic Forwarding on an IPQoS-Enabled Network

DS Codepoint

Per-Hop Behaviors

Expedited Forwarding

Assured Forwarding

Packet Forwarding in a Diffserv Environment

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)



Traffic Forwarding on an IPQoS-Enabled Network

This section introduces the elements that are involved in forwarding packets on an IPQoS-enabled network. An IPQoS-enabled system handles any packets on the network stream with the system's IP address as the destination. The IPQoS system then applies its QoS policy to the packet to establish differentiated services.

DS Codepoint

The DS codepoint (DSCP) defines in the packet header the action that any Diffserv-aware system should take on a marked packet. The diffserv architecture defines a set of DS codepoints for the IPQoS-enabled system and diffserv router to use. The Diffserv architecture also defines a set of actions that are called forwarding behaviors, which correspond to the DSCPs. The IPQoS-enabled system marks the precedence bits of the DS field in the packet header with the DSCP. When a router receives a packet with a DSCP value, the router applies the forwarding behavior that is associated with that DSCP. The packet is then released onto the network.

Note - The dlcosmk marker does not use the DSCP. Rather, dlcosmk marks Ethernet frame headers with a CoS value. If you plan to configure IPQoS on a network that uses VLAN devices, refer to Marker Module.

Per-Hop Behaviors

In Diffserv terminology, the forwarding behavior that is assigned to a DSCP is called the per-hop behavior (PHB). The PHB defines the forwarding precedence that a marked packet receives in relation to other traffic on the Diffserv-aware system. This precedence ultimately determines whether the IPQoS-enabled system or Diffserv router forwards or drops the marked packet. For a forwarded packet, each Diffserv router that the packet encounters en route to its destination applies the same PHB. The exception is if another Diffserv system changes the DSCP. For more information on PHBs, refer to Using the dscpmk Marker for Forwarding Packets.

The goal of a PHB is to provide a specified amount of network resources to a class of traffic on the contiguous network. You can achieve this goal in the QoS policy. Define DSCPs that indicate the precedence levels for traffic classes when the traffic flows leave the IPQoS-enabled system. Precedences can range from high-precedence/low-drop probability to low-precedence/high-drop probability.

For example, your QoS policy can assign to one class of traffic a DSCP that guarantees a low-drop PHB. This traffic class then receives a low-drop precedence PHB from any Diffserv-aware router, which guarantees bandwidth to packets of this class. You can add to the QoS policy other DSCPs that assign varying levels of precedence to other traffic classes. The lower-precedence packets are given bandwidth by Diffserv systems in agreement with the priorities that are indicated in the packets' DSCPs.

IPQoS supports two types of forwarding behaviors, which are defined in the Diffserv architecture, expedited forwarding and assured forwarding.

Expedited Forwarding

The expedited forwarding (EF) per-hop behavior assures that any traffic class with EFs related DSCP is given highest priority. Traffic with an EF DSCP is not queued. EF provides low loss, latency, and jitter. The recommended DSCP for EF is 101110. A packet that is marked with 101110 receives guaranteed low-drop precedence as the packet traverses Diffserv-aware networks en route to its destination. Use the EF DSCP when assigning priority to customers or applications with a premium SLA.

Assured Forwarding

The assured forwarding (AF) per-hop behavior provides four different forwarding classes that you can assign to a packet. Every forwarding class provides three drop precedences, as shown in Table 32-2.

The various AF codepoints provide the ability to assign different levels of service to customers and applications. In the QoS policy, you can prioritize traffic and services on your network when you plan the QoS policy. You can then assign different AF levels to the prioritized traffic.

Packet Forwarding in a Diffserv Environment

The following figure shows part of an intranet at a company with a partially Diffserv-enabled environment. In this scenario, all hosts on networks and are IPQoS enabled, and the local routers on both networks are Diffserv aware. However, the interim networks are not configured for Diffserv.

Figure 27-2 Packet Forwarding Across Diffserv-Aware Network Hops

image:The context follows the graphic, which is a flow diagram

The next steps trace the flow of the packet that is shown in this figure. The steps begin with the progress of a packet that originates at host ipqos1. The steps then continue through several hops to host ipqos2.

  1. The user on ipqos1 runs the ftp command to access host ipqos2, which is three hops away.

  2. ipqos1 applies its QoS policy to the resulting packet flow. ipqos1 then successfully classifies the ftp traffic.

    The system administrator has created a class for all outgoing ftp traffic that originates on the local network Traffic for the ftp class is assigned the AF22 per-hop behavior: class two, medium-drop precedence. A traffic flow rate of 2Mb/sec is configured for the ftp class.

  3. ipqos-1 meters the ftp flow to determine if the flow exceeds the committed rate of 2 Mbit/sec.

  4. The marker on ipqos1 marks the DS fields in the outgoing ftp packets with the 010100 DSCP, corresponding to the AF22 PHB.

  5. The router diffrouter1 receives the ftp packets. diffrouter1 then checks the DSCP. If diffrouter1 is congested, packets that are marked with AF22 are dropped.

  6. ftp traffic is forwarded to the next hop in agreement with the per-hop behavior that is configured for AF22 in diffrouter1's files.

  7. The ftp traffic traverses network to genrouter, which is not Diffserv aware. As a result, the traffic receives “best-effort” forwarding behavior.

  8. genrouter passes the ftp traffic to network, where the traffic is received by diffrouter2.

  9. diffrouter2 is Diffserv aware. Therefore, the router forwards the ftp packets to the network in agreement with the PHB that is defined in the router policy for AF22 packets.

  10. ipqos2 receives the ftp traffic. ipqos2 then prompts the user on ipqos1 for a user name and password.