Administrator Guide

Similar to ‘dscp’ qualifier in the existing L3 ACL command, the ‘ecn’ qualifier can be used along with all other supported ACL
match qualifiers such as SIP/DIP/TCP/UDP/SRC PORT/DST PORT/ ICMP.
Until Release 9.3(0.0), ACL supports classification based on the below TCP flags:
● ACK
● FIN
● SYN
● PSH
● RST
● URG
You can now use the ‘ecn’ match qualifier along with the above TCP flag for classification.
The following combination of match qualifiers is acceptable to be configured for the Dell EMC Networking OS software through
L3 ACL command:
● Classification based on DSCP only
● Classification based on ECN only
● Classification based on ECN and DSCP concurrently
You can now use the set-color yellow keyword with the match ip access-group command to mark the color of the traffic as
‘yellow’ would be added in the ‘match ip’ sequence of the class-map configuration.
By default, all packets are considered as ‘green’ (without the rate-policer and trust-diffserve configuration) and hence support
would be provided to mark the packets as ‘yellow’ alone will be provided.
By default Dell EMC Networking OS drops all the ‘RED’ or ‘violate’ packets.
The following combination of marking actions to be specified match sequence of the class-map command:
● set a new DSCP for the packet
● set the packet color as ‘yellow’
● set the packet color as ‘yellow’ and set a new DSCP for the packet
This marking action to set the color of the packet is allowed only on the ‘match-any’ logical operator of the class-map.
This marking-action can be configured for all of the below L3 match sequence types:
● match ip access-group
● match ip dscp
● match ip precedence
● match ip vlan
Guidelines for Configuring ECN for Classifying and
Color-Marking Packets
Keep the following points in mind while configuring the marking and mapping of incoming packets using ECN fields in IPv4
headers:
● Currently Dell EMC Networking OS supports matching only the following TCP flags:
○ ACK
○ FIN
○ SYN
○ PSH
Quality of Service (QoS)
657