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## Examples: Setting Up Forwarding Preferences

We provide two examples for setting up forwarding preferences.

## Setting Up Forwarding Preferences by Using CoS on JUNOS Routing Platforms

The sample data provides an implementation that supports CoS features on the JUNOS routing platform. This implementation provides:

- Basic BoD services to apply a JUNOS policer only to best-effort traffic
- BoD services to assign traffic to forwarding classes other than best-effort
- Policing for best-effort traffic

Table 16 lists the services and policies in the sample data. You can locate the services in l=entJunos, o=Scopes, o=umc. You can customize the policies and services as needed. For general information about configuring policies and services, see Configuring Basic BoD Policies and Configuring BoD Policies .

Table 16: Integrated BoD and Basic BoD Services in Sample Data

Name of Service | Category of Service | Name of Policy Group | Description of Service
--- | --- | --- | ---
1.0 Mbps | basic BoD | basic BoD | Specifies that a bandwidth of 1.0 Mbps be available to a specified access link for best-effort traffic.
3.0 Mbps | basic BoD | basic BoD | Specifies that a bandwidth of 3.0 Mbps be available to a specified access link for best-effort traffic.
5.0 Mbps | basic BoD | basic BoD | Specifies that a bandwidth of 5.0 Mbps be available to a specified access link for best-effort traffic.
Silver | BoD | BoD | Marks associated traffic as belonging to an assured forwarding class.
Gold | BoD | BoD | Marks associated traffic as belonging to an expedited forwarding class.

Billing can be established for traffic in the assured forwarding class and in the expedited forwarding class because the SRC software can account for traffic in each of these forwarding classes separately from other forwarding classes. Traffic in the assured forwarding class and in the expedited forwarding class is not included in the accounting data for the currently selected basic BoD service.

## Setting Up Forwarding Preferences by Allocating a Percentage of a Link’s Bandwidth to a Service

The following example shows another way to use BoD and basic BoD services to provide BoD services. In this example, a percentage of an access link’s bandwidth is allocated to a specified service.

This configuration provides:

- Three bandwidth levels available to access links: 1.0 Mbps, 1.5 Mbps, and 2.0 Mbps.
- Three service levels defined to use a specified percentage of the bandwidth set for the access link: best effort 20%, Silver 30%, and Gold 50%.

  Each traffic class uses only the bandwidth assigned to it and does not share bandwidth with other traffic classes.

For an SRC configuration to support this scenario, you could create policies such as the following and assign these policies to services:

- Policies that provide a local policy parameter, bw, whose value is set by the service that references the policy:

  For policy 1.0 Mb, bw=1000000

  For policy 1.5 Mb, bw=1500000

  For policy 2.0 Mb, bw= 2000000

- The transmission rate, bandwidth allocation, and priority scheduling for specified forwarding classes as shown in Table 17.

  Table 17: Policies to Specify Forwarding Treatment for Specified Traffic Classes

  Forwarding Class | Transmission Rate | Exact | Priority Scheduling
  --- | --- | --- | ---
  Best effort | bw*0.2 bps | true | Low
  Silver (assured forwarding) | bw*0.3 bps | true | Medium
  Gold (expedited forwarding) | bw*0.5 bps | true | High

By setting exact to true, you can ensure that the sum of the transmission rates is less than the bandwidth allocated to the access link.

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