3com 3031 Instruccion De Instalación

Frame Relay congestion management is applied at the egress interface on a Frame 
Relay switched device. If there is no congestion, the router will normally forward 
the Frame Relay packets without doing any special processing on them. Once 
there is congestion, the packets that are marked with the DE flag bit will be 
discarded. As for the forward packets to be forwarded, the router will set the 
FECN flag bit in the Frame Relay packet headers to 1. As for the backward packets 
on the same PVC, the router will set the BECN flag bit in the Frame Relay packet 
headers to 1. If there is no backward packets to be forwarded after a certain 
period, the router will automatically transmit the Q922A Test Reponse packets 
with the BECN flag bit 1 to the calling DTE.

Figure 251   Frame Relay congestion management

In a Frame Relay network, the packets that are marked with DE flag bit will be first 
discarded once there is congestion. The DE rule lists are applied on the Frame 
Relay PVCs on a router, and each of them contains multiple DE rules. If a packet 
transmitted on a PVC complies with the rules in the DE rule list, its DE flag bit will 
be set to 1, and the packets like it will be discarded first if the congestion occurs 
on the network.

 The V2.0 software integrates the QoS on Frame Relay PVCs into Frame Relay 
class. Thereby, it provides a flexible overall solution to Frame Relay traffic control 
and quality service. Before configuring such QoS as Frame Relay traffic shaping, 
you need to create a Frame Relay class, and configure various QoS parameters on 
it. Such a Frame Relay class equals to a set of QoS network service solution. Then, 
the user can associate it with a Frame Relay PVC. It is equivalent to applying a set 
of QoS scheme to the Frame Relay PVC. Different PVCs can use different Frame 
Relay classes or a single Frame Relay class.

Frame Relay class configuration includes:

■

Create a Frame Relay class

■

Associate the Frame Relay class with the Frame Relay interface or a PVC

■

Configure the Frame Relay class parameters

Perform the following in the System View.

Frame-relay network

Router B

Router A

DTE

NNI

DCE

BECN

FECN

Data flow direction

Table 1069   Creating/Deleting a Frame Relay class

Create a Frame Relay class