IP::tos

Description

Returns (or sets) the ToS value encoded within a packet. The Type of Service (ToS) standard is a means by which network equipment can identify and treat traffic differently based on an identifier. As traffic enters the site, the BIG-IP system can apply a rule that sends the traffic to different pools of servers based on the ToS level within a packet, or can set the ToS value on traffic matching specific patterns.
Note: If using DSCP values, know that is a bit-shifted value within the tos field, so if you need the value to be DSCP 46, the actual value you need to use with the command is 184 (bit-shifted twice, so 22=4 * DSCP = TOS) . Please use this table for refererence:
In normal english, take the DSCP value and multiply by 4 to get the IP::tos value.
DSCP Mappings for IP::tos Command
Precedence Type of Service DSCP Class DSCP Value IP::tos Value
0 0 none 0 0
1 0 cs1 8 32
1 1 af11 10 40
1 10 af12 12 48
1 11 af13 14 56
10 0 cs2 16 64
10 1 af21 18 72
10 10 af22 20 80
10 11 af23 22 88
11 0 cs3 24 96
11 1 af31 26 104
11 10 af32 28 112
11 11 af33 30 120
100 0 cs4 32 128
100 1 af41 34 136
100 10 af42 36 144
100 11 af43 38 152
101 0 cs5 40 160
101 11 ef 46 184
110 0 cs6 48 192
111 0 cs7 56 224

This command is equivalent to the BIG-IP 4.X variable ip_tos.

Syntax

IP::tos

IP::tos

  • Returns or sets the ToS value encoded within a packet.

Examples

Set IP::tos to DSCP class cs2 (dscp 16 -> tos 64)

when CLIENT_ACCEPTED {
  if { [IP::tos] == 64 } {
     pool telnet_pool
  } else {
     pool slow_pool
 }
}


when CLIENT_ACCEPTED {
  if { [TCP::local_port] == 554 } {
    # this sets DSCP to 46 (EF)
    IP::tos 184
  }
}