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The following table describes the WRED and ECN operations that occur for various scenarios of WRED and ECN configuration on
the queue and service pool. (X denotes not-applicable in the table, 1 indicates that the setting is enabled, 0 represents a disabled
setting. )
Table 76. Scenarios of WRED and ECN Configuration
Queue
Configuration
Service-Pool
Configuration
WRED Threshold
Relationship
Q threshold = Q-T,
Service pool threshold
= SP-T
Expected Functionality
WRED
ECN
WRED
ECN
0
0
X
X
X
WRED/ECN not applicable
1
0
0
X
X
Queue based WRED,
No ECN marking
1
X
Q-T < SP-T
SP-T < Q-T
SP based WRED,
No ECN marking
1
1
0
X
X
Queue-based ECN marking above queue threshold.
ECN marking to shared buffer limits of the service-pool and
then packets are tail dropped.
1
X
Q-T < SP-T
SP-T < Q-T
Same as above but ECN marking starts above SP-T.
Configuring WRED and ECN Attributes
The functionality to configure a weight factor for the WRED and ECN functionality for backplane ports is supported on the Z9000
platform.
WRED drops packets when the average queue length exceeds the configured threshold value to signify congestion. 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.
To configure the weight factor for WRED and ECN capabilities, global buffer pools for multiple queues, and associating a service
class with ECN marking, perform the following:
1.
Configure the weight factor for the computation of average-queue size. This weight value applies to front-end ports.
QOS-POLICY-OUT mode
Dell(conf-qos-policy-out)#wred—profile weight
number
2.
Configure a WRED profile, and specify the threshold and maximum drop rate.
WRED mode
Dell(conf-wred) #wred—profile thresh-1
Dell(conf-wred) #threshold min 100 max 200 max-drop-rate 40
3.
Configure another WRED profile, and specify the threshold and maximum drop rate.
WRED mode
Dell(conf-wred) #wred—profile thresh-2
698
Quality of Service (QoS)
Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...