Chapter 4 Broadband
45
eircom D10
00 modem User’s Guide
4.5.6 NAT
NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in
a packet, for example, the source address of an outgoing packet, used within one network to a
different IP address known within another network.
4.6 Traffic Shaping
Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate
and fluctuations of data transmission over an ATM network. This agreement helps eliminate
congestion, which is important for transmission of real time data such as audio and video
connections.
Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may
be lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a
maximum speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed
because it is dependent on the line speed.
Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the
maximum average rate at which cells can be sent over the virtual connection. SCR may not be
greater than the PCR.
Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS
is reached, cell rates fall below SCR until cell rate averages to the SCR again. At this time, more
cells (up to the MBS) can be sent at the PCR again.
If the PCR, SCR or MBS is set to the default of "0", the system will assign a maximum value that
correlates to your upstream line rate.
The following figure illustrates the relationship between PCR, SCR and MBS.
Figure 18
Example of Traffic Shaping
4.6.1 ATM Traffic Classes
These are the basic ATM traffic classes defined by the ATM Forum Traffic Management 4.0
Specification.
Summary of Contents for eircom D1000
Page 2: ...Copyright 2013 ZyXEL Communications Corporation...
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Page 12: ...10 eircom D1000 modem User s Guide...
Page 13: ...PART I User s Guide 11...
Page 14: ...12...
Page 18: ...16 eircom D1000 modem User s Guide...
Page 26: ...Chapter 2 Introducing the Web Configurator 24 eircom D1000 modem User s Guide...
Page 27: ...PART II Technical Reference 25...
Page 28: ...26...
Page 78: ...76 eircom D1000 modem User s Guide Chapter 5 Wireless LAN...
Page 110: ...10 8 eircom D1000 modem User s Guide Chapter 6 Home Networking...
Page 126: ...Chapter 8 Quality of Service QoS 124 eircom D1000 modem User s Guide...
Page 136: ...134 eircom D1000 modem User s Guide Chapter 9 Network Address Translation NAT...
Page 148: ...146 eircom D1000 modem User s Guide Chapter 12 Filter...
Page 168: ...Chapter 14 Parental Control 166 eircom D1000 modem User s Guide...
Page 174: ...Chapter 15 Certificates 172 eircom D1000 modem User s Guide...
Page 180: ...178 eircom D1000 modem User s Guide Chapter 17 Traffic Status...
Page 182: ...180 eircom D1000 modem User s Guide Chapter 18 User Account...
Page 184: ...182 eircom D1000 modem User s Guide Chapter 19 System Setting...
Page 187: ...185 eircom D1000 modem User s Guide Chapter 20 Time Setting...
Page 188: ...Chapter 20 Time Setting 186 eircom D1000 modem User s Guide...
Page 196: ...Chapter 23 Backup Restore 194 eircom D1000 modem User s Guide...
Page 210: ...Chapter 25 Diagnostic 208 eircom D1000 modem User s Guide...
Page 216: ...214 eircom D1000 modem User s Guide Chapter 27 LED Descriptions...