R3303-HP HSR6800 Routers ACL and QoS Configuration Guide

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FR congestion management
FR congestion management can process FR packets when congestion occurs in the network. It drops the
packets with the DE flag bits set to 1 and notifies other devices on the network about the congestion.
FR congestion management is applied on the outgoing interface of an FR switching device. If no
congestion occurs, the FR switching device forwards the FR packets without any processing. If congestion
occurs, packets with the FE flag bits set to 1 are dropped. As for forward packets to be forwarded, the
FECN flag bits in the FR packet headers are set to 1. As for backward packets on the same PVC, the
BECN flag bits in the FR packet headers are set to 1. If no backward packets are transmitted within a
period, the device automatically transmits the packets with the BECN flag bits set to 1 to the calling DTE.
Figure 48 FR congestion management implementation
FR DE rule list
In an FR network, packets with the DE flag bits set to 1 are dropped first when congestion occurs in the
network. DE rule lists are applied on the FR PVCs of a device, with each DE rule list containing multiple
DE rules. If a packet transmitted over the PVC matches the rules in the DE rule list, its DE flag bit is set to
1. The packet is dropped first when congestion occurs in the network.
FR QoS configuration task list
Task Remarks
Creating and configuring an FR class Required.
Configuring FRTS Optional.
Configuring FR traffic policing Optional.
Configuring FR congestion management Optional.
Configuring FR DE rule list Optional.
Configuring FR fragmentation Optional.
Creating and configuring an FR class
An FR class specifies a set of QoS parameters for traffic control and regulation on FR PVCs. To provide
QoS on a PVC, create an FR class, set QoS parameters such as FRTS settings in the class, and map the
class to the PVC.
You can map an FR class to PVCs by mapping it to FR interfaces or DLCIs.
帧中继网络
DTE
DCE
NNI
Router A
Router B
Data flow direction
BECN
FECN
Frame-Relay
network
Frame relay
network