Sample Configuration To Mark Non-Ecn Packets As "Yellow" With Multiple Traffic Class; Classifying Incoming Packets Using Ecn And Color-Marking - Dell Z9000 Configuration Manual

– 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
seq 5 permit any ecn 0
class-map match-any ecn_0_cmap
match ip access-group ecn_0 set-color
!
policy-map-input ecn_0_pmap
service-queue 0 class-map ecn_0_cmap
Applying this policy-map "ecn_0_pmap" will mark all the packets with 'ecn == 0' as yellow packets on
queue0 (default queue).

Classifying Incoming Packets Using ECN and Color-Marking

Explicit Congestion Notification (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 configure 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 significant 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
Quality of Service (QoS)
yellow
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