Chapter 10 Quality of Service (QoS)
VMG1312-B Series User’s Guide
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The srTCM evaluat es incom ing packet s and m arks t hem wit h one of t hree colors which refer t o
packet loss priorit y levels. High packet loss priorit y level is referred t o as red, m edium is referred t o
as yellow and low is referred t o as green.
The srTCM is based on t he t oken bucket filt er and has t wo t oken bucket s ( CBS and EBS) . Tokens
are generat ed and added int o t he bucket at a const ant rat e, called Com m it t ed I nform at ion Rat e
( CI R) . When t he first bucket ( CBS) is full, new t okens overflow int o t he second bucket ( EBS) .
All packet s are evaluat ed against t he CBS. I f a packet does not exceed t he CBS it is m arked green.
Ot herwise it is evaluat ed against t he EBS. I f it is below t he EBS t hen it is m arked yellow. I f it
exceeds t he EBS t hen it is m arked red.
The following shows how t okens work wit h incom ing packet s in srTCM:
• A packet arrives. The packet is m arked green and can be t ransm it t ed if t he num ber of t okens in
t he CBS bucket is equal t o or great er t han t he size of t he packet ( in byt es) .
• Aft er a packet is t ransm it t ed, a num ber of t okens corresponding t o t he packet size is rem oved
from t he CBS bucket .
• I f t here are not enough t okens in t he CBS bucket , t he Device checks t he EBS bucket . The packet
is m arked yellow if t here are sufficient t okens in t he EBS bucket . Ot herwise, t he packet is m arked
red. No t okens are rem oved if t he packet is dropped.
Two Rate Three Color Marker
The Two Rat e Three Color Marker ( t rTCM, defined in RFC 2698) is a t ype of t raffic policing t hat
ident ifies packet s by com paring t hem t o t wo user- defined rat es: t he Com m it t ed I nform at ion Rat e
( CI R) and t he Peak I nform at ion Rat e ( PI R) . The CI R specifies t he average rat e at which packet s are
adm it t ed t o t he net work. The PI R is great er t han or equal t o t he CI R. CI R and PI R values are based
on t he guarant eed and m axim um bandwidt h respect ively as negot iat ed bet ween a service provider
and client .
The t rTCM evaluat es incom ing packet s and m arks t hem wit h one of t hree colors which refer t o
packet loss priorit y levels. High packet loss priorit y level is referred t o as red, m edium is referred t o
as yellow and low is referred t o as green.
The t rTCM is based on t he t oken bucket filt er and has t wo t oken bucket s ( Com m it t ed Burst Size
( CBS) and Peak Burst Size ( PBS) ) . Tokens are generat ed and added int o t he t wo bucket s at t he CI R
and PI R respect ively.
All packet s are evaluat ed against t he PI R. I f a packet exceeds t he PI R it is m arked red. Ot herwise it
is evaluat ed against t he CI R. I f it exceeds t he CI R t hen it is m arked yellow. Finally, if it is below t he
CI R t hen it is m arked green.
The following shows how t okens work wit h incom ing packet s in t rTCM:
• A packet arrives. I f t he num ber of t okens in t he PBS bucket is less t han t he size of t he packet ( in
byt es) , t he packet is m arked red and m ay be dropped regardless of t he CBS bucket . No t okens
are rem oved if t he packet is dropped.
• I f t he PBS bucket has enough t okens, t he Device checks t he CBS bucket . The packet is m arked
green and can be t ransm it t ed if t he num ber of t okens in t he CBS bucket is equal t o or great er
t han t he size of t he packet ( in byt es) . Ot herwise, t he packet is m arked yellow.
Summary of Contents for VMG1312-B Series
Page 4: ...Contents Overview VMG1312 B Series User s Guide 4 Troubleshooting 289 ...
Page 14: ...Table of Contents VMG1312 B Series User s Guide 14 ...
Page 15: ...15 PART I User s Guide ...
Page 16: ...16 ...
Page 30: ...Chapter 2 The Web Configurator VMG1312 B Series User s Guide 30 ...
Page 35: ...Chapter 4 Tutorials VMG1312 B Series User s Guide 35 7 Click Apply to save your settings ...
Page 77: ...77 PART II Technical Reference ...
Page 78: ...78 ...
Page 166: ...Chapter 9 Routing VMG1312 B Series User s Guide 166 ...
Page 184: ...Chapter 10 Quality of Service QoS VMG1312 B Series User s Guide 184 ...
Page 210: ...Chapter 13 Interface Group VMG1312 B Series User s Guide 210 ...
Page 226: ...Chapter 15 Firewall VMG1312 B Series User s Guide 226 ...
Page 232: ...Chapter 17 Parental Control VMG1312 B Series User s Guide 232 ...
Page 242: ...Chapter 19 Certificates VMG1312 B Series User s Guide 242 ...
Page 246: ...Chapter 20 Log VMG1312 B Series User s Guide 246 ...
Page 250: ...Chapter 21 Traffic Status VMG1312 B Series User s Guide 250 ...
Page 256: ...Chapter 24 IGMP Status VMG1312 B Series User s Guide 256 ...
Page 260: ...Chapter 25 xDSL Statistics VMG1312 B Series User s Guide 260 ...
Page 262: ...Chapter 26 User Account VMG1312 B Series User s Guide 262 ...
Page 268: ...Chapter 29 TR 064 VMG1312 B Series User s Guide 268 ...
Page 272: ...Chapter 30 Time Settings VMG1312 B Series User s Guide 272 ...
Page 278: ...Chapter 32 Logs Setting VMG1312 B Series User s Guide 278 ...
Page 296: ...Chapter 36 Troubleshooting VMG1312 B Series User s Guide 296 ...
Page 336: ...Appendix C Pop up Windows JavaScripts and Java Permissions VMG1312 B Series User s Guide 336 ...
Page 350: ...Appendix D Wireless LANs VMG1312 B Series User s Guide 350 ...
Page 374: ...VMG1312 B Series User s Guide 374 Index ...