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Token Bucket, Single Rate Three Color Marker

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Chapter 10 Quality of Service (QoS) Token Bucket The token bucket algorithm uses tokens in a bucket to control when traffic can be transmitted. The bucket stores tokens, each of which represents one byte. The algorithm allows bursts of up to b bytes which is also the bucket size, so the bucket can hold up to b tokens. Tokens are generated and added into the bucket at a constant rate. The following shows how tokens work with packets: • A packet can be transmitted if the number of tokens in the bucket is equal to or greater than the size of the packet (in bytes). • After a packet is transmitted, a number of tokens corresponding to the packet size is removed from the bucket. • If there are no tokens in the bucket, the VMG stops transmitting until enough tokens are generated. • If not enough tokens are available, the VMG treats the packet in either one of the following ways: In traffic shaping: • Holds it in the queue until enough tokens are available in the bucket. In traffic policing: • Drops it. • Transmits it but adds a DSCP mark. The VMG may drop these marked packets if the network is overloaded. Configure the bucket size to be equal to or less than the amount of the bandwidth that the interface can support. It does not help if you set it to a bucket size over the interface's capability. The smaller the bucket size, the lower the data transmission rate and that may cause outgoing packets to be dropped. A larger transmission rate requires a big bucket size. For example, use a bucket size of 10 kbytes to get the transmission rate up to 10 Mbps. Single Rate Three Color Marker The Single Rate Three Color Marker (srTCM, defined in RFC 2697) is a type of traffic policing that identifies packets by comparing them to one user-defined rate, the Committed Information Rate (CIR), and two burst sizes: the Committed Burst Size (CBS) and Excess Burst Size (EBS). The srTCM evaluates incoming packets and marks them with one of three colors which refer to packet loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and low is referred to as green. The srTCM is based on the token bucket filter and has two token buckets (CBS and EBS). Tokens are generated and added into the bucket at a constant rate, called Committed Information Rate (CIR). When the first bucket (CBS) is full, new tokens overflow into the second bucket (EBS). All packets are evaluated against the CBS. If a packet does not exceed the CBS it is marked green. Otherwise it is evaluated against the EBS. If it is below the EBS then it is marked yellow. If it exceeds the EBS then it is marked red. The following shows how tokens work with incoming packets in srTCM: • A packet arrives. The packet is marked green and can be transmitted if the number of tokens in the CBS bucket is equal to or greater than the size of the packet (in bytes). • After a packet is transmitted, a number of tokens corresponding to the packet size is removed from the CBS bucket. VMG3925-B10A User's Guide 155

Section	Page
VMG3925-B10A	1
Contents Overview	3
Table of Contents	5
User’s Guide	14
Introducing the VMG	15
1.1 Overview	15
1.2 Ways to Manage the VMG	15
1.3 Good Habits for Managing the VMG	15
1.4 Applications for the VMG	16
1.4.1 Internet Access	16
1.4.2 VMG’s USB Support	16
1.5 LEDs (Lights)	17
1.6 The RESET Button	19
1.7 Wireless Access	20
1.7.1 Using the Wi-Fi and WPS Buttons	20
The Web Configurator	21
2.1 Overview	21
2.1.1 Accessing the Web Configurator	21
2.2 Web Configurator Layout	23
2.2.1 Title Bar	23
2.2.2 Main Window	24
2.2.3 Navigation Panel	25
Quick Start	29
3.1 Overview	29
3.2 Quick Start Setup	29
Tutorials	31
4.1 Overview	31
4.2 Setting Up an ADSL PPPoE Connection	31
4.3 Setting Up a Secure Wireless Network	34
4.3.1 Configuring the Wireless Network Settings	34
4.3.2 Using WPS	36
4.3.3 Without WPS	40
4.4 Setting Up Multiple Wireless Groups	41
4.5 Configuring Static Route for Routing to Another Network	44
4.6 Configuring QoS Queue and Class Setup	46
4.7 Access the VMG Using DDNS	50
4.7.1 Registering a DDNS Account on www.dyndns.org	50
4.7.2 Configuring DDNS on Your VMG	51
4.7.3 Testing the DDNS Setting	51
4.8 Configuring the MAC Address Filter	51
4.9 Access Your Shared Files From a Computer	53
Technical Reference	54
Network Map and Status Screens	55
5.1 Overview	55
5.2 The Network Map Screen	55
5.3 The Status Screen	56
Broadband	59
6.1 Overview	59
6.1.1 What You Can Do in this Chapter	59
6.1.2 What You Need to Know	60
6.1.3 Before You Begin	62
6.2 The Broadband Screen	63
6.2.1 Add/Edit Internet Connection	64
6.3 The 3G Backup Screen	71
6.4 The Advanced Screen	75
6.5 The 802.1x Screen	78
6.5.1 Modify 802.1X Settings	79
6.6 Technical Reference	79
Wireless	85
7.1 Overview	85
7.1.1 What You Can Do in this Chapter	85
7.1.2 What You Need to Know	85
7.2 The General Screen	86
7.2.1 No Security	88
7.2.2 Basic (WEP Encryption)	88
7.2.3 More Secure (WPA(2)-PSK)	89
7.3 The Guest / More AP Screen	91
7.3.1 Edit Guest / More AP	91
7.4 The MAC Authentication Screen	93
7.5 The WPS Screen	94
7.6 The WMM Screen	96
7.7 The WDS Screen	97
7.7.1 WDS Scan	98
7.8 The Others Screen	99
7.9 The Channel Status Screen	101
7.10 Technical Reference	102
7.10.1 Wireless Network Overview	102
7.10.2 Additional Wireless Terms	104
7.10.3 Wireless Security Overview	104
7.10.4 Signal Problems	106
7.10.5 BSS	107
7.10.6 MBSSID	107
7.10.7 Preamble Type	108
7.10.8 Wireless Distribution System (WDS)	108
7.10.9 WiFi Protected Setup (WPS)	108
Home Networking	116
8.1 Overview	116
8.1.1 What You Can Do in this Chapter	116
8.1.2 What You Need To Know	117
8.1.3 Before You Begin	118
8.2 The LAN Setup Screen	118
8.3 The Static DHCP Screen	122
8.4 The UPnP Screen	123
8.4.1 Turning On UPnP in Windows 7 Example	124
8.5 The Additional Subnet Screen	126
8.6 The STB Vendor ID Screen	127
8.7 The Wake on LAN Screen	127
8.8 The TFTP Server Name Screen	128
8.9 Technical Reference	128
8.9.1 LANs, WANs and the VMG	128
8.9.2 DHCP Setup	129
8.9.3 DNS Server Addresses	129
8.9.4 LAN TCP/IP	130
Routing	132
9.1 Overview	132
9.2 The Routing Screen	132
9.2.1 Add/Edit Static Route	133
9.3 The DNS Route Screen	134
9.3.1 The DNS Route Add Screen	135
9.4 The Policy Route Screen	135
9.4.1 Add/Edit Policy Route	137
9.5 RIP	138
9.5.1 The RIP Screen	138
Quality of Service (QoS)	139
10.1 Overview	139
10.1.1 What You Can Do in this Chapter	139
10.2 What You Need to Know	140
10.3 The Quality of Service General Screen	141
10.4 The Queue Setup Screen	142
10.4.1 Adding a QoS Queue	144
10.5 The Classification Setup Screen	144
10.5.1 Add/Edit QoS Classifier	145
10.6 The QoS Shaper Setup Screen	149
10.6.1 Add/Edit a QoS Shaper	150
10.7 The QoS Policer Setup Screen	150
10.7.1 Add/Edit a QoS Policer	151
10.8 Technical Reference	152
Network Address Translation (NAT)	157
11.1 Overview	157
11.1.1 What You Can Do in this Chapter	157
11.1.2 What You Need To Know	157
11.2 The Port Forwarding Screen	158
11.2.1 Add/Edit Port Forwarding	160
11.3 The Applications Screen	161
11.3.1 Add New Application	162
11.4 The Port Triggering Screen	162
11.4.1 Add/Edit Port Triggering Rule	164
11.5 The DMZ Screen	165
11.6 The ALG Screen	166
11.7 The Address Mapping Screen	166
11.7.1 Add/Edit Address Mapping Rule	167
11.8 The Sessions Screen	168
11.9 Technical Reference	169
11.9.1 NAT Definitions	169
11.9.2 What NAT Does	169
11.9.3 How NAT Works	170
11.9.4 NAT Application	170
DNS Setup	173
12.1 Overview	173
12.1.1 What You Can Do in this Chapter	173
12.1.2 What You Need To Know	173
12.2 The DNS Entry Screen	174
12.2.1 Add/Edit DNS Entry	174
12.3 The Dynamic DNS Screen	175
IGMP/MLD	177
13.1 Overview	177
13.1.1 What You Need To Know	177
13.2 The IGMP/MLD Screen	177
VLAN Group	180
14.1 Overview	180
14.1.1 What You Can Do in this Chapter	180
14.2 The Vlan Group Screen	180
14.2.1 Add/Edit a VLAN Group	181
Interface Group	183
15.1 Overview	183
15.1.1 What You Can Do in this Chapter	183
15.2 The Interface Group Screen	183
15.2.1 Interface Group Configuration	184
15.2.2 Interface Grouping Criteria	186
USB Service	188
16.1 Overview	188
16.1.1 What You Can Do in this Chapter	188
16.1.2 What You Need To Know	188
16.1.3 Before You Begin	189
16.2 The File Sharing Screen	189
16.2.1 The Add New User Screen	190
16.3 The Media Server Screen	191
Firewall	193
17.1 Overview	193
17.1.1 What You Can Do in this Chapter	193
17.1.2 What You Need to Know	194
17.2 The Firewall Screen	194
17.3 The Protocol Screen	195
17.3.1 Add/Edit a Protocol	196
17.4 The Access Control Screen	197
17.4.1 Add/Edit an ACL Rule	197
17.5 The DoS Screen	199
MAC Filter	200
18.1 Overview	200
18.2 The MAC Filter Screen	200
Parental Control	202
19.1 Overview	202
19.2 The Parental Control Screen	202
19.2.1 Add/Edit a Parental Control Profile	203
Scheduler Rule	206
20.1 Overview	206
20.2 The Scheduler Rule Screen	206
20.2.1 Add/Edit a Schedule	206
Certificates	208
21.1 Overview	208
21.1.1 What You Can Do in this Chapter	208
21.2 What You Need to Know	208
21.3 The Local Certificates Screen	208
21.3.1 Create Certificate Request	209
21.3.2 Load Signed Certificate	211
21.4 The Trusted CA Screen	212
21.4.1 View Trusted CA Certificate	213
21.4.2 Import Trusted CA Certificate	214
Log	215
22.1 Overview	215
22.1.1 What You Can Do in this Chapter	215
22.1.2 What You Need To Know	215
22.2 The System Log Screen	216
22.3 The Security Log Screen	216
Traffic Status	218
23.1 Overview	218
23.1.1 What You Can Do in this Chapter	218
23.2 The WAN Status Screen	218
23.3 The LAN Status Screen	219
23.4 The NAT Status Screen	220
ARP Table	221
24.1 Overview	221
24.1.1 How ARP Works	221
24.2 ARP Table Screen	221
Routing Table	223
25.1 Overview	223
25.2 The Routing Table Screen	223
Multicast Status	225
26.1 Overview	225
26.2 The IGMP Status Screen	225
26.3 The MLD Status Screen	225
xDSL Statistics	227
27.1 The xDSL Statistics Screen	227
3G Statistics	230
28.1 Overview	230
28.2 The 3G Statistics Screen	230
System	232
29.1 Overview	232
29.2 The System Screen	232
User Account	233
30.1 Overview	233
30.2 The User Account Screen	233
30.2.1 The User Account Add/Edit Screen	233
Remote Management	235
31.1 Overview	235
31.2 The Remote MGMT Screen	235
31.3 The Trust Domain Screen	236
31.3.1 The Add Trust Domain Screen	236
SNMP	238
32.1 Overview	238
32.2 The SNMP Screen	238
Time Settings	240
33.1 Overview	240
33.2 The Time Screen	240
E-mail Notification	243
34.1 Overview	243
34.2 The E-mail Notification Screen	243
34.2.1 Email Notification Edit	243
Log Setting	245
35.1 Overview	245
35.2 The Log Settings Screen	245
35.2.1 Example E-mail Log	246
Firmware Upgrade	248
36.1 Overview	248
36.2 The Firmware Screen	248
Backup Restore	250
37.1 Overview	250
37.2 The Backup Restore Screen	250
37.3 The Reboot Screen	252
Diagnostic	253
38.1 Overview	253
38.1.1 What You Can Do in this Chapter	253
38.2 What You Need to Know	253
38.3 Ping & TraceRoute & NsLookup	254
38.4 802.1ag	254
38.5 OAM Ping	255
Troubleshooting	258
39.1 Power, Hardware Connections, and LEDs	258
39.2 VMG Access and Login	259
39.3 Internet Access	261
39.4 Wireless Internet Access	262
39.5 USB Device Connection	263
39.6 UPnP	263
Appendices	265
Customer Support	266
Wireless LANs	272
IPv6	285
Services	293
Legal Information	297

Match case Limit results 1 per page

Chapter 10 Quality of Service (QoS)

VMG3925-B10A User’s Guide

155

Token Bucket

The token bucket algorithm uses tokens in a bucket to control when traffic can be transmitted. The

bucket stores tokens, each of which represents one byte. The algorithm allows bursts of up to

bytes which is also the bucket size, so the bucket can hold up to

tokens. Tokens are generated

and added into the bucket at a constant rate. The following shows how tokens work with packets:

•

A packet can be transmitted if the number of tokens in the bucket is equal to or greater than the

size of the packet (in bytes).

•

After a packet is transmitted, a number of tokens corresponding to the packet size is removed

from the bucket.

•

If there are no tokens in the bucket, the VMG stops transmitting until enough tokens are

generated.

•

If not enough tokens are available, the VMG treats the packet in either one of the following ways:

In traffic shaping:

•

Holds it in the queue until enough tokens are available in the bucket.

In traffic policing:

•

Drops it.

•

Transmits it but adds a DSCP mark. The VMG may drop these marked packets if the network is

overloaded.

Configure the bucket size to be equal to or less than the amount of the bandwidth that the interface

can support. It does not help if you set it to a bucket size over the interface’s capability. The smaller

the bucket size, the lower the data transmission rate and that may cause outgoing packets to be

dropped. A larger transmission rate requires a big bucket size. For example, use a bucket size of 10

kbytes to get the transmission rate up to 10 Mbps.

Single Rate Three Color Marker

The Single Rate Three Color Marker (srTCM, defined in RFC 2697) is a type of traffic policing that

identifies packets by comparing them to one user-defined rate, the Committed Information Rate

(CIR), and two burst sizes: the Committed Burst Size (CBS) and Excess Burst Size (EBS).

The srTCM evaluates incoming packets and marks them with one of three colors which refer to

packet loss priority levels. High packet loss priority level is referred to as red, medium is referred to

as yellow and low is referred to as green.

The srTCM is based on the token bucket filter and has two token buckets (CBS and EBS). Tokens

are generated and added into the bucket at a constant rate, called Committed Information Rate

(CIR). When the first bucket (CBS) is full, new tokens overflow into the second bucket (EBS).

All packets are evaluated against the CBS. If a packet does not exceed the CBS it is marked green.

Otherwise it is evaluated against the EBS. If it is below the EBS then it is marked yellow. If it

exceeds the EBS then it is marked red.

The following shows how tokens work with incoming packets in srTCM:

•

A packet arrives. The packet is marked green and can be transmitted if the number of tokens in

the CBS bucket is equal to or greater than the size of the packet (in bytes).

•

After a packet is transmitted, a number of tokens corresponding to the packet size is removed

from the CBS bucket.