Extreme Networks BlackDiamond 6800 MPLS Guide de l'utilisateur télécharger pdf (Page 58)

3-18 MPLS Module Installation and User Guide

Configuring the MPLS Module

Two mappings are supported:

• dot1p-to-exp

• exp-to-dot1p

Dot1p-to-exp Mappings

The dot1p-to-exp mappings are used by the ingress LSR. When a non-MPLS ingress

frame arrives at the MPLS module, the frame always contains an IEEE 802.1p priority

field.

The value of the priority field is set based on the QoS classification performed by the

ingress I/O module. The ingress I/O modules assign each packet to a hardware queue,

based on the configured ExtremeWare QoS policies. There is a one-to-one mapping

between the hardware queue and the 802.1p priority values that are inserted into

frames forwarded to the MPLS module. For example, the 802.1p priority value is set to

0 for frames forwarded from hardware queue 0, set to 1 for frames forwarded from

hardware queue 1, and so on.

The dot1p-to-exp table maps 802.1 priority values to MPLS EXP values. The table is

completely flexible, such that any 802.1p priority

<input_value>

can be mapped to any

EXP

<output_value>

. The EXP output_value is set in the MPLS header of the packet as

it is forwarded to the MPLS network.

Exp-to-dot1p Mappings

The exp-to-dot1p mappings are used when the switch performs label swapping as an

intermediate LSR and when the switch is the egress LSR. In both of these cases, the

MPLS module receives an MPLS-encapsulated frame.

The EXP field in the frame is used as an

<input_value>

to the exp-to-dot1p table. The

corresponding

<output_value>

is an 802.1p priority value. The 802.1p priority value is

inserted into the frame before the frame is forwarded by the MPLS module.

The exp-to-dot1p table is completely flexible, such that any EXP

<input_value>

can be

mapped to any 802.1p priority

<output_value>

The exp-to-dot1p table is also used by Packet over SONET (PoS) ports when classifying

MPLS-encapsulated packets received from the SONET link. When a PoS port receives

an MPLS-encapsulated packet from the SONET link, the packet is classified based on

the EXP value in the MPLS shim header. The EXP value from the received frame is used

as an index into the exp-to-dot1p mapping table to retrieve and 802.1p priority value.

1 2 ... 53 54 55 56 57 58 59 60 61 62 63 ... 175 176

Commentaires sur ces manuels

Pas de commentaire

Extreme Networks BlackDiamond 6800 MPLS Guide de l'utilisateur Page 58

Commentaires sur ces manuels

Produits connexes et manuels pour Commutateurs de réseau Extreme Networks BlackDiamond 6800 MPLS