Concept Guide

As a part of this feature, the 2-bit ECN eld of the IPv4 packet will also be available to be congured as one of the match qualier. This way
the entire 8-bit ToS eld of the IPv4 header shall be used to classify trac.
The Dell EMC Networking OS Release 9.3(0.0) supports the following QOS actions in the ingress policy based QOS:
1 Rate Policing
2 Queuing
3 Marking
For the L3 Routed packets, the DSCP marking is the only marking action supported in the software. As a part of this feature, the additional
marking action to set the “color” of the trac will be provided.
Until Release 9.3(0.0), the software has the capability to qualify only on the 6-bit DSCP part of the ToS eld in IPv4 Header. You can now
accept and process incoming packets based on the 2-bit ECN part of the ToS eld in addition to the DSCP categorization. The IPv4 ACLs
(standard and Extended) are enhanced to add this qualier. This new keyword ‘ecn’ is present for all L3 ACL types (TCP/UDP/IP/ICMP) at
the level where the ‘DSCP’ qualier is positioned in the current ACL commands.
Dell EMC Networking OS supports the capability to contain DSCP and ECN classiers simultaneously for the same ACL entry.
You can use the ecn keyword with the ip access-list standard, ip access-list extended, seq, and permit commands for standard and
extended IPv4 ACLs to match incoming packets with the specied ECN values.
Similar to ‘dscp’ qualier in the existing L3 ACL command, the ‘ecn’ qualier can be used along with all other supported ACL match
qualiers such as SIP/DIP/TCP/UDP/SRC PORT/DST PORT/ ICMP.
Until Release 9.3(0.0), ACL supports classication based on the below TCP ags:
• ACK
• FIN
• SYN
• PSH
• RST
• URG
You can now use the ‘ecn’ match qualier along with the above TCP ag for classication.
The following combination of match qualiers is acceptable to be congured for the Dell EMC Networking OS software through L3 ACL
command:
• Classication based on DSCP only
• Classication based on ECN only
• Classication 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 trac as ‘yellow’ would
be added in the ‘match ip’ sequence of the class-map conguration.
By default, all packets are considered as ‘green’ (without the rate-policer and trust-diserve conguration) 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 specied match sequence of the class-map command:
• set a new DSCP for the packet
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Quality of Service (QoS)