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Issue 1a - 10/99
8-17
Introduction to Frame Relay
There is also a mechanism in Frame Relay for an end user
device to prioritize its frames. It does this by setting the
DE (Discard Eligibility) bit in the frame header. The DE
bit tells the network to ‘discard these frames first’. By
marking some traffic as DE, Frame Relay users can
prioritize their non-DE traffic.
The network also has the ability to set a frame’s DE bit.
For example, this may be used to prevent a high
bandwidth device, such as a graphics workstation, from
taking all the bandwidth from a low bandwidth device.
Committed Information Rate & Burst Size
In order to be able to guarantee a certain level of service and
control access to the Frame Relay network service providers
offer a number of service parameters. These are :
•
Committed Information Rate (CIR). The CIR is the
minimum rate of service which can be expected
from a virtual circuit, under normal conditions.
Transmissions in excess of the CIR may be
discarded if there is congestion in the network.
However, it is also possible to get a better rate than the
CIR when there is available bandwidth.
•
Committed Burst Size (Bc). This is the maximum
number of bits that the network attempts to deliver,
under normal conditions, within a given time period
(Tc). The CIR is equal to the committed burst size
divided by time interval Tc (CIR = Bc/Tc)
•
Excess Burst Size (Be). This is the maximum number of
bits by which the user may exceed the Committed
Burst Size, within a given time period (Tc). The
network will attempt to send these but they are likely
to be discarded during periods of congestion.
Содержание auroraTempo
Страница 2: ...423972 Issue 1a 10 99 auroraTempo User Guide ...
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Страница 27: ...Issue 1a 10 99 2 1 Power Sources Power Sources Contents Using AC Power 2 2 Using Battery Power 2 2 ...
Страница 35: ...Issue 1a 10 99 3 3 Getting Started Connecting auroraTempo within the Frame Relay Network ...
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Страница 56: ...auroraTempo User Guide 4 8 423972 The following table provides a key to the T1 display ...
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Страница 120: ...auroraTempo User Guide 5 40 423972 The information displayed is described in the following table ...
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Страница 196: ...auroraTempo User Guide 6 18 423972 Emulation DTE Clock Source Line Speed 64kbs Handshake Yes 1 V X Interface Defaults ...
Страница 197: ...Issue 1a 10 99 6 19 Configuring auroraTempo ...
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Страница 242: ...auroraTempo User Guide A1 6 423972 34 Way MRAC Winchester Connector Male Part number 423355 ...
Страница 243: ...Issue 1a 10 99 A1 7 Appendix 1 Technical Data RS449 Interface 37 Way D Type Connector Male Part number 423354 ...
Страница 244: ...auroraTempo User Guide A1 8 423972 X21 Interface 15 Way D Type Connector Male Part number 423353 ...
Страница 245: ...Issue 1a 10 99 A1 9 Appendix 1 Technical Data V24 RS232 Interface 25 Way D Type Connector Male Part number 423352 ...
Страница 246: ...auroraTempo User Guide A1 10 423972 EIA530 Interface 25 Way D Type Connector Male Part number 423360 ...
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Страница 267: ...Issue 1a 10 99 A4 1 Appendix 4 Glossary Appendix 4 Contents Glossary A4 2 ...
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Страница 281: ...Issue 1a 10 99 A5 1 Appendix 5 RFC 1490 Decode Appendix 5 Appendix 5 Contents RFC 1490 Decode A5 2 ...
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Страница 285: ...Issue 1a 10 99 Index 1 Index ...
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