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 Networking OS supports matching only the following TCP flags:
• ACK
• FIN
• SYN
• PSH
• RST
• URG
In the existing software, ECE/CWR TCP flag qualifiers are not supported.
• Because this functionality forcibly marks all the packets matching the specific match criteria as ‘yellow’,
Dell Networking OS does not support Policer based coloring and this feature concurrently.
• If single rate two color policer is configured along with this feature, then by default all packets less than
PIR would be considered as “Green” But ‘Green’ packets matching the specific match criteria for which
‘color-marking’ is configured will be over-written and marked as “Yellow”.
• If two rate three color policer is configured along with this feature then,
• x < CIR – will be marked as “Green”
• CIR < x< PIR – will be marked as “Yellow”
• PIR < x – will be marked as “Red”
But ‘Green’ packets matching the specific match criteria for which ‘color-marking’ is configured will be over-
written and marked as “Yellow”.
Sample configuration to mark non-ecn
packets as “yellow” with Multiple traffic
class
Consider the example where there are no different traffic classes that is all the packets are egressing on the
default ‘queue0’.
Dell Networking OS can be configured as below to mark the non-ecn packets as yellow packets.
!
ip access-list standard ecn_0
Quality of Service (QoS) 868
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