TOS priority
settings for TosDSCP INI
Routers
treat network packets differently based on priority of the TOS
tag in the IP header.
IP header has a 1-byte field called
TOS—Type of Service.
IP precedence is older than DSCP. DSCP
is compatible with IP Precedence.
Table 1. TOS priority settingsTOS priority settings
|
Bit7 |
Bit6 |
Bit5 |
Bit4 |
Bit3 |
Bit2 |
Bit1 |
Bit0 |
IP precedence |
IP precedence |
|
|
|
|
|
DSCP |
DSCP |
|
|
Class Selector |
Drop Precedence |
CS1 Dscp (001 000) match packets with precedence 1 (Low)
CS2 Dscp (010 000) match packets with precedence 2
CS3 Dscp
(011 000) match packets with precedence 3
CS4 Dscp (100 000)
match packets with precedence 4
CS5 Dscp (101 000) match packets
with precedence 5
CS6 Dscp (110 000) match packets with precedence
6
CS7 Dscp (111 000) match packets with precedence 7 (High)
Table 2. TOS priority settingsTOS priority settings
IP precedence(3
bits) |
DSCP (
6 bits) |
Name |
Value |
bits |
Per-Hop
behavior |
ClassSelector |
DropPrecedence |
Code point
Name |
DSCP Bits(decimal) |
|
Routine |
0 |
0 |
Default |
NA |
NA |
Default |
000 000
(0) |
Priority |
1 |
1 |
AF |
1 |
1.Low |
AF11 |
001 010
(10) |
2.Medium |
AF12 |
001 100
(12) |
3.High |
AF13 |
001 110
(14) |
Immediate |
2 |
10 |
AF |
2 |
1.Low |
AF21 |
010 010
(18) |
2.Medium |
AF22 |
010 100
(20) |
3.High |
AF23 |
010 110
(22) |
Flash |
3 |
11 |
AF |
3 |
1.Low |
AF31 |
011 010
(26) |
2.Medium |
AF32 |
011 100
(28) |
3.High |
AF33 |
011 110
(30) |
Flash Override |
4 |
100 |
AF |
4 |
1.Low |
AF41 |
100 010
(34) |
2.Medium |
AF42 |
100 100
(36) |
3.High |
AF43 |
100 110
(38) |
Critical |
5 |
101 |
EF |
NA |
NA |
EF |
101 110
(46) |
Internetwork
Control |
6 |
110 |
NA |
NA |
NA |
NA |
(48-55) |
Network
Control |
7 |
111 |
NA |
NA |
NA |
NA |
(56-63) |
Table 3. TOS priority settingsTOS priority settings
IP precedence (3 bits) |
DSCP ( 6 bits) |
Name |
Useful |
Name |
Useful |
Routine |
Try as usual |
NA |
NA |
Priority |
For data traffic |
AF11 |
Big block
data |
Immediate |
NA |
NA |
Flash |
For Voice
control data |
NA |
NA |
Flash Override |
Video streaming |
NA |
NA |
Critical |
Voice Data |
EF |
Interactive
Voice |
Internetwork
Control |
Reserved |
NA |
NA |
NetworkControl |
NA |
NA |
NA |
NA |
NOTE:The information in this section is leveraged based on the research on web. Specific priority
designs must be arranged by network architect.