Nokia 7705 - Page 140

QoS and QoS Policies
140
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
Note:
1. The default queue mapping for dot1p values 2 and 3 are both queue 3.
3.7.5.1.1 CoS Marking for Self-generated Traffic
The 7705 SAR is the source of some types of traffic; for example, a link state PDU
for sending IS-IS topology updates or an SNMP trap sent to indicate that an event
has happened. This type of traffic that is created by the 7705 SAR is considered to
be self-generated traffic (SGT). Another example of self-generated traffic is Telnet,
but in that application, user commands initiate the sending of the Telnet traffic.
Network operators often have different QoS models throughout their networks and
apply different QoS schemes to portions of the networks in order to better
accommodate delay, jitter, and loss requirements of different applications. The class
of service (DSCP or dot1p) bits of self-generated traffic can be marked on a
per-application basis to match the network operator’s QoS scheme. This marking
option enhances the ability of the 7705 SAR to match the various requirements of
these applications.
The 7705 SAR supports marking self-generated traffic for the base routers and for
virtual routers. Refer to “QoS Policies” in the 7705 SAR Services Guide for
information on SGT QoS as applied to virtual routers (for VPRN services).
The DSCP and dot1p values of the self-generated traffic, where applicable, are
marked in accordance with the values that are configured under the sgt-qos
command. In the egress direction, self-generated traffic is forwarded using the
egress control queue to ensure premium treatment, unless SGT redirection is
configured (see SGT Redirection). PTP (IEEE 1588v2) and SAA-enabled ICMP
traffic is forwarded using the CoS queue. The next-hop router uses the DSCP values
to classify the traffic accordingly.
67In
78In
Table 27 Default Network QoS Policy Dot1p-to-Queue Class Mappings
Dot1p Value Queue Profile State
Note: IS-IS and ARP traffic are not IP-generated traffic types and are not
DSCP-configurable; however, the dot1p bits can be configured in the same way as the
DSCP bits. The default setting for the dot1p bits for both types of traffic is 111. For all other
applications, the dot1p bits are marked based on the mapped network egress forwarding
class.