
Link Scheduler Configuration
125
Procedure
Defining the type-of-service (TOS) field
Mode
Source
Command Purpose
node
(src)[
name
]#set ip tos
value
Defines the type-of-service (TOS) value applied
to packets of for the
selected class or policy
name
. Valid values for
value
are 0, 1, 2, 4, and 8,
as given in Table 15-2.
15.8.6 Specifying the Precedence Field
The
set ip precedence
command specifies the precedence marking applied to packets of the class
name
. Precedence and DSCP markings cannot be used at the same time.
The type-of-service (TOS) byte in an IP header specifies precedence (priority) and type of service
(RFC791, RFC1349). The precedence field is defined by the first three bits and supports eight levels of
priority. The lowest priority is assigned to 0 and the highest priority is 7. The values 6 and 7 are
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,
Software Configuration Guide, Revision 1.03
and