Defining The Maximum Queue Length; Specifying The Type-Of-Service (Tos) Field - Patton electronics SmartNode Series Software Configuration Manual

SmartWare Software Configuration Guide
Defining the maximum queue length
The command queue-limit specifies the maximum number of packets queued for the class name. Excess pack-
ets are dropped. Used in "class" mode—queuing only happens at the leaf of the arbitration hierarchy tree. The
no form of this command reverts the queue-limit to the internal default value, which depends on your config-
uration.
This procedure describes defining maximum queue length
Mode: Source
Command
node (src)[ name ]#queue-limit
number-of-packets
Specifying the type-of-service (TOS) field
The set ip tos command specifies the type-of-service (TOS) field value applied to packets of the class name. TOS
and DSCP markings cannot be used at the same time. The no form of this command disables TOS marking.
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 next
four bits—which are set by the set ip tos command—determine the type-of-service (TOS). Only one of these
bits can be turned on. Each bit determines a specific method for the router to select a path.
TOS Value SmartWare Value
1000
0100
0010
0001
0000
Because TOS values are integers rather than sets of bits, computing the logical OR of two TOS values is not
meaningful. For example, it would be a serious error for a router to choose a low delay path for a packet whose
requested TOS was 1110 simply because the link scheduler noted that the former delay bit was set.
This procedure describes defining the type-of-service (TOS) field
Link scheduler configuration task list
Defines the maximum number of packets queued for the selected class
or policy name
Table 9. TOS values and their meaning
8 This bit minimizes the delay. The delay bit tells the link scheduler to
choose high speed to minimize delay. This bit would typically be set for
voice.
4 This bit maximizes throughput. The throughput bit specifies high capacity
links used for bulk transfers.
2 This bit maximizes reliability. Routing protocols and network manage-
ment applications use this for fault tolerant paths.
1 This bit minimizes monetary costs. The cost bit is for low priority applica-
tions such as NNTP and signifies the lowest cost path.
0 If all bits are cleared normal service is selected, which is referred as
"default TOS".
13 • Link scheduler configuration
Purpose
Meaning
151