![ZyXEL Communications VMG4325-B10A User Manual Download Page 176](http://html.mh-extra.com/html/zyxel-communications/vmg4325-b10a/vmg4325-b10a_user-manual_944368176.webp)
Chapter 10 Quality of Service (QoS)
VMG4380-B10A / VMG4325-B10A User’s Guide
176
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 Device stops transmitting until enough tokens are
generated.
• If not enough tokens are available, the Device 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 Device 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).
6
6
4
100110
100100
100010
100000
5
101110
101000
7
7
6
110000
111000
7
Table 53
Internal Layer2 and Layer3 QoS Mapping
PRIORITY
QUEUE
LAYER 2
LAYER 3
IEEE 802.1P USER
PRIORITY
(ETHERNET
PRIORITY)
TOS (IP
PRECEDENCE)
DSCP
IP PACKET
LENGTH (BYTE)
Summary of Contents for VMG4325-B10A
Page 4: ...Contents Overview VMG4380 B10A VMG4325 B10A User s Guide 4 Troubleshooting 283 ...
Page 14: ...Table of Contents VMG4380 B10A VMG4325 B10A User s Guide 14 ...
Page 15: ...15 PART I User s Guide ...
Page 16: ...16 ...
Page 24: ...Chapter 1 Introducing the Device VMG4380 B10A VMG4325 B10A User s Guide 24 ...
Page 69: ...69 PART II Technical Reference ...
Page 70: ...70 ...
Page 178: ...Chapter 10 Quality of Service QoS VMG4380 B10A VMG4325 B10A User s Guide 178 ...
Page 204: ...Chapter 13 Interface Group VMG4380 B10A VMG4325 B10A User s Guide 204 ...
Page 220: ...Chapter 15 Firewall VMG4380 B10A VMG4325 B10A User s Guide 220 ...
Page 226: ...Chapter 17 Parental Control VMG4380 B10A VMG4325 B10A User s Guide 226 ...
Page 236: ...Chapter 19 Certificates VMG4380 B10A VMG4325 B10A User s Guide 236 ...
Page 240: ...Chapter 20 Log VMG4380 B10A VMG4325 B10A User s Guide 240 ...
Page 244: ...Chapter 21 Traffic Status VMG4380 B10A VMG4325 B10A User s Guide 244 ...
Page 250: ...Chapter 24 IGMP Status VMG4380 B10A VMG4325 B10A User s Guide 250 ...
Page 254: ...Chapter 25 xDSL Statistics VMG4380 B10A VMG4325 B10A User s Guide 254 ...
Page 256: ...Chapter 26 User Account VMG4380 B10A VMG4325 B10A User s Guide 256 ...
Page 262: ...Chapter 29 TR 064 VMG4380 B10A VMG4325 B10A User s Guide 262 ...
Page 266: ...Chapter 30 Time Settings VMG4380 B10A VMG4325 B10A User s Guide 266 ...
Page 272: ...Chapter 32 Logs Setting VMG4380 B10A VMG4325 B10A User s Guide 272 ...
Page 290: ...Chapter 36 Troubleshooting VMG4380 B10A VMG4325 B10A User s Guide 290 ...
Page 344: ...Appendix D Wireless LANs VMG4380 B10A VMG4325 B10A User s Guide 344 ...