Inalp Networks SmartWare Release 2.10, Руководство по настройке программного обеспечения

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Link Scheduler Configuration 123
reserved for network control packets. Therefore, with the set ip precedence command the values 0
through 5 can be set for priority based on IP networks or applications.
The
no form of this command disables precedence marking.
Procedure
Defining the precedence field
Mode
Source
Command Purpose
node (src)[ name ]#set ip precedence value
Defines the precedence marking value applied
to packets of for the
selected class or policy
name . The range for value is from 0 to 7, but
only values from 0 to 5 should be used.
15.8.7 Specifying Differentiated Services Codepoint Marking
Differentiated services enhancements to the Internet protocol are intended to enable scalable service
discrimination in an IP network without the need for per-flow state and signaling at every hop. A
variety of services may be built from a small, well-defined set of building blocks, which are deployed
in network nodes. The services may be either end-to-end or intra-domain; they include both those
that can satisfy quantitative performance requirements (e.g., peak bandwidth) and those based on
relative performance (e.g. "class" differentiation). Services can be constructed by a combination of:
•
setting bits in an IP header field at network boundaries (autonomous system boundaries,
internal administrative boundaries, or hosts),
• using those bits to determine how packets are forwarded by the nodes inside the network,
and
• conditioning the marked packets at network boundaries in accordance with the
requirements or rules of each service.
The requirements or rules of each service must be set through administrative policy mechanisms,
which are outside the scope of this user guide. A differentiated services-compliant network node
includes a classifier that selects packets based on the value of the DS field, along with buffer
management and packet scheduling mechanisms capable of delivering the specific packet
forwarding treatment indicated by the DS field value. Setting of the DS field and conditioning of the
temporal behavior of marked packets need only be performed at network boundaries and may vary
in complexity.
In the IP header field, called the DS (for differentiated services) field is illustrated. Six bits of the DS
field are used as a codepoint (DSCP) to select the per-hop behavior (PHB) a packet experiences at
each node. A two-bit currently unused (CU) field is reserved and its definition and interpretation are
outside the scope of this document. Differentiated services-compliant nodes when determining the
per-hop behavior to apply to a received packet ignore the value of the CU bits.
Software Configuration Guide Release 2.10, Revision 1.00