3Com 10014299 manual Frame Relay Congestion Management, Frame Relay DE rule list

262CHAPTER 17: CONFIGURING FRAME RELAY

Frame Relay Congestion Management

Frame Relay congestion management can process the Frame Relay packets whenever there is network congestion. It will discard the packets that are marked with the DE flag bit. At the same time, it will notify other devices on the network about the congestion.

Frame Relay congestion management is applied at the output 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 87 Frame Relay congestion management

	Data flow direction
BECN
DCE		NNI	Frame-relay network
DTE
Router A	Router B	FECN

Frame Relay DE rule list

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.

Configure Frame Relay The 3Com Router system integrates the QoS on Frame Relay PVCs into Frame class Relay class. Thereby, it provides a flexible overall solution to Frame Relay traffic

control and quality service. Before configuring the QoS such 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 as well as 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

1Create a Frame Relay class

Perform the following configurations in system view.