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 traffic 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
field in IPv4 Header. You can now accept and process incoming packets based on the 2-bit ECN part of
the ToS field in addition to the DSCP categorization. The IPv4 ACLs (standard and Extended) are
enhanced to add this qualifier. This new keyword ‘ecn’ is present for all L3 ACL types (TCP/UDP/IP/ICMP)
at the level where the ‘DSCP’ qualifier is positioned in the current ACL commands.
Dell Networking OS supports the capability to contain DSCP and ECN classifiers 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 specified ECN
values.
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 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 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:
Quality of Service (QoS) 759