R3303-HP HSR6800 Routers High Availability Configuration Guide

Configure the RPR fairness algorithm

By configuring the RPR fairness algorithm, you can better guarantee the transmission quality over RPR

rings.

Configuring reserved bandwidth or rate limiting

RPR traffic includes three classes: class A, class B, and class C, with decreasing priorities.

• Class A is further divided into two subclasses: A0 and A1. RPR can reserve bandwidth for subclass

A0. When congestion occurs, the unused reserved bandwidth cannot be used by lower priority

traffic. Subclass A1 is rate limited. When congestion occurs, subclass A1 allows lower priority

traffic to use its unused bandwidth, and bandwidth allocation is regulated by the fairness algorithm.

• Class B can also be divided into two subclasses: B-CIR and B-EIR. For class B traffic, the portion

within the predefined rate limit belongs to class B-CIR and the portion exceeding the limit belongs

to class B-EIR. Similar to traffic of class C, traffic of class B-EIR is regulated by the fairness algorithm.

• Traffic of class C is regulated by the fairness algorithm and takes the lowest priority.

To configure reserved bandwidth or rate limit for a certain traffic class:

Ste

Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RPR logical

interface view.

interface rpr interface-number N/A

3. Configure reserved

bandwidth or rate limit

for a class on a certain

ringlet.

rpr rate-limiter { high | low |

medium | reserved } { ringlet0 |

ringlet1 } value

By default, no bandwidth is reserved for

subclass A0. The rate limit is 2‰ for

subclass A1, 0‰ for class B-CIR, and

1000‰ for B-EIR and class C.

NOTE:

The total bandwidth reserved for subclass A0 by the stations on a ringlet must be less than the ringlet

bandwidth.

Configuring station weight

On an RPR ring, bandwidth resources are shared among stations. When traffic size is small, RPR can

handle bandwidth requests of all stations on the ring. When traffic size gets heavy, congestion might

occur. To prevent some stations from taking advantage of their spatially or chronologically favorable

position on the ring to occupy excessive bandwidth, RPR adopts a fairness algorithm to ensure

bandwidth allocation fairness.

The fairness algorithm of RPR mainly regulates class B-EIR and class C traffic on the RPR ring. You can

assign a weight to a station to adjust the ratio of its available service bandwidth to the total non-reserved

bandwidth on a ringlet. The fairness weight of a station is configured as an exponent of two.

To configure the fairness weight of an RPR station on a ringlet: