AIS AI2524 user manual Configure Dlci Priority Levels, Frame-relay de-group group-number dlci

Chapter 13: AI2524 Frame Relay Configuration Steps

Configure Discard Eligibility

You can specify which Frame Relay packets have low priority or low time sensitivity and will be the first to be dropped when a Frame Relay switch is congested. The mechanism that allows a Frame Relay switch to identify such packets is the discard eligibility (DE) bit.

This feature requires that the Frame Relay network be able to interpret the DE bit. Some networks take no action when the DE bit is set. Other networks use the DE bit to determine which packets to discard. The most desirable interpretation is to use the DE bit to determine which packets should be dropped first and also which packets have lower time sensitivity.

You can define DE lists that identify the characteristics of packets to be eligible for discarding, and you can also specify DE groups to iden- tify the DLCI that is affected.

zIn global configuration mode, define a DE list specifying which packets can be dropped when the Frame Relay switch is congest- ed:

frame-relay de-list list-number{protocol protocol interface type number} characteristic

You can specify DE lists based on the protocol or the interface, and on characteristics such as fragmentation of the packet, a specific TCP o User Datagram Protocol (UDP) port, an access list number, or a packet size.

zIn interface configuration mode, define a DE group specifying th DE list and DLCI affected:

frame-relay de-group group-number dlci

Configure DLCI Priority Levels

DLCI priority levels allow you to separate different types of traffic and can provide a traffic management tool for congestion problems caused by these situations:

zMixing batch and interactive traffic over the same DLC

zTraffic from sites with high-speed access being queued at destina- tion sites with lower speed access

August 1997	Page 13-45
2524UM