Specifications

70 IBM Voice Over Frame Relay Perform Guide
The DE bit can be set by the router to indicate that some traffic should be
considered discard eligible. If appropriate, the frame relay network will discard
frames marked as discard eligible which may allow frames that are not marked
discard eligible, to make it through the network. To identify traffic that is discard
eligible:
1. Configure BRS on the frame relay interface and any FR circuits that have
traffic that you are making discard eligible.
2. Assign a protocol or filter to a BRS traffic class using the
assign command.
You specify whether the DE bit should be set on for this protocol or filter traffic.
This is the explanation of effectiveness of DE. The customer usually does not
care about DE using a frame relay network. When congestion occurs, a frame
relay switch will discard a customer frame regardless of whether it is important
SNA or unimportant IP traffic.
Figure 39. Frame Relay DE bit:OFF
Figure 40. Frame Relay DE bit:OFF Discard Frame
Frame Relay Network
FR swith
FR switch
SNA(DLSw) :
DE bit "OFF"
IP (FTP) :
DE bit "OFF"
IP Traffic (FTP)
SNA Traffic (DLSw )
SNA Traffic (DLSw )IP Traffic (FTP)
Delay
Congestion
Delay
2212
2212
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P
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A
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F
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IP Traffic
(FTP)
IP Traffic
(FTP)
SN A Traffic (D LS w )
congetion
SNA Traffic (DLSw )