NEC UNIVERGE SV9100 Manual page 18

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complete.
Header Checksum - Helps ensure IP header integrity. Since some header fields change, e.g., Time
To Live, this is recomputed and verified at each point that the Internet header is processed.
Source Address - Specifies the sending node.
Destination Address - Specifies the receiving node.
Options - Allows IP to support various options, such as security.
Data - Contains upper-layer information.
3.4 IP Precedence
IP Precedence is a QoS method that combines a priority value with three different on/off parameters;
Delay, Throughput, and Reliability.
Using the ToS bits, you can define up to 8 classes of service. Other devices configured throughout
the network can then use these bits to determine how to treat the packet in regard to the type of
service to grant it. These other QoS features can assign appropriate traffic-handling policies including
congestion management and bandwidth allocation. By setting IP Precedence levels on incoming
traffic and using them in combination with QoS queuing features, you can create differentiated
service.
3 bits
IP Precedence Value
IP Precedence Values
Value Binary Value
0 000
1 001
2 010
3 011
4 100
5 101
6 110
7 111
Delay
Value Description
Normal delay
0
Low delay
1
Throughput
Value Description
Type of Service Field (IP Precedence)
1 bit
Delay
Description
Routine
Priority
Immediate
Flash
Flash override
CRITIC/ECP
Internetwork control
Network control
1 bit 1 bit
Throughput Reliability
2 bits
Currently Un-used