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CONFIGURATION mode
Dell(conf)#class-map match-all pp_classmap
2 Congure a DSCP value as a match criterion.
CLASS-MAP mode
Dell(conf-class-map)#match ipdscp 5
3 Congure an IP VLAN ID as a match criterion.
CLASS-MAP mode
Dell(conf-class-map)#match ip vlan 5
4 Create a QoS input policy.
CONFIGURATION mode
Dell(conf)#qos-policy-input pp_qospolicy
5 Congure the DSCP value to be set on matched packets.
QOS-POLICY-IN mode
Dell(conf-qos-policy-in)#set ip-dscp 5
6 Create an input policy map.
CONFIGURATION mode
Dell(conf)#policy-map-input pp_policmap
7 Create a service queue to associate the class map and QoS policy map.
POLICY-MAP mode
Dell(conf-policy-map-in)#service-queue 0 class-map pp_classmap qos-policy pp_qospolicy
Classifying Incoming Packets Using ECN and Color-
Marking
Explicit Congestion Notication (ECN) is a capability that enhances WRED by marking the packets instead of causing WRED to drop them
when the threshold value is exceeded. If you congure ECN for WRED, devices employ this functionality of ECN to mark the packets and
reduce the rate of sending packets in a congested, heavily-loaded network.
ECN is a mechanism using which network switches indicate congestion to end hosts for initiating appropriate action. End hosts uses two
least signicant bits of ToS to indicate that it is ECT. When intermediate network node encounters congestion, remarks ECT to CE for end
host to take appropriate action. During congestion, ECN enabled packets are not subject to any kind of drops like WRED except tail drops.
Though ECN & WRED are independent technologies, BRCM has made WRED a mandatory for ECN to work.
On ECN deployment, the non-ECN packets that are transmitted on the ECN-WRED enabled interface will be considered as Green packets
and will be subject to the early WRED drops. Typically the TCP-acks, OAM, ICMP ping packets will be non-ECN in nature and it is not
desirable for this packets getting WRED dropped.
In such a condition, it is necessary that the switch is capable to take dierentiated actions for ECN/Non-ECN packets. After classifying
packets to ECN/Non-ECN, marking ECN and Non-ECN packets to dierent color packets is performed.
Policy based ingress QOS involves the following three steps to achieve QOS:
1 Classication of incoming trac.
2 Specify the dierentiated actions for dierent trac class.
3 Attach the policy-map to the interface.
Dell EMC Networking OS support dierent types of match qualiers to classify the incoming trac.
Quality of Service (QoS)
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