LevelOne GSW-0890 user manual IP ToS Classification

Function name:

IP ToS Classification

Function description:

Another QoS function is the application of Layer 3 on network framework. We focus on TOS field of IP header. There are three bits in TOS field. We means bit 5~7 of TOS field that we will use. According to these 3 bits, we could arrange 8 traffics –0 0 0, 0 0 1, 0 1 0, 0 1 1, 1 0 0, 1 0 1, 1 1 0, 1 1 1. As long as we change bit 5~7 of TOS field of IP header, we will create the 8 traffic packets we meant before. Moreover, we can set High priority or Low priority for each traffic class. For instance, if we let TOS 0 0 0 be high priority and TOS 0 0 1 be Low Priority, we sent in the packets that have bit 5~7 of TOS Field appears 0 0 0 from the port 2 and the packets that have bit 5~7 of TOS Field appears 0 0 1 from the port 3. We let the two kinds of packets be transmitted for port 1 until the port results in congestion. The result is that the packets will be dropped partially from the port 3 because the packets that belong to Low Priority.

Fig. 3-20

Parameter description:

Quality of Service (QoS) ToS Configuration: Used for setting up the QoS in Layer 3.

Port:

User can set up the port (1~8) respectively to let TOS QoS function work on them. If you would like to set up all ports at a time, user is also allowed to choose “All” in the selection list to simplify the procedure of configuration.

Bit 0, Bit 1, Bit 2:

According to the arrangement of Bit 5 ~ Bit 7 in TOS Field of IP Header, it can form 8 kinds of traffics, including 0 0 0, 0 0 1, 0 1 0, 0 1 1, 1 0 0, 1 0 1, 1 1 0 and 1 1 1.

Class:

8 kinds of traffic as mentioned above, user can set up High Priority or Low Priority for each port respectively.

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