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The following table shows you the internal layer-2 and layer-3 QoS mapping on the ZyXEL Device.
On the ZyXEL Device, traffic assigned to higher priority queues gets through faster while traffic in
lower index queues is dropped if the network is congested.
Table 42 Internal Layer2 and Layer3 QoS Mapping
PRIORITY
QUEUE
0
1
2
3
4
5
6
7
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.
P-873HNUP-51B User's Guide
LAYER 2
LAYER 3
IEEE 802.1P USER
PRIORITY
TOS (IP
(ETHERNET
PRECEDENCE)
PRIORITY)
1
0
2
0
0
3
1
4
2
5
3
6
4
5
7
6
7
Chapter 10 Quality of Service (QoS)
IP PACKET
DSCP
LENGTH (BYTE)
000000
000000
>1100
001110
250~1100
001100
001010
001000
010110
010100
010010
010000
011110
<250
011100
011010
011000
100110
100100
100010
100000
101110
101000
110000
111000
155
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