Service-Pool Wred - Dell Z9500 Reference Manual

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By default, ECN marking is disabled on all queues.

CONFIGURATION mode

You can add or remove ECN marking configuration on a list of queues on all

backplane ports. All of the configured attributes apply to all the backplane ports

and are for each queue. You can configure all the data queues. For the Z9500, you

can configure queues 0-7. By default, ECN marking is disabled on all queues. When

you enable WRED with ECN and the number of packets in the queue is below the

minimum threshold, packets are transmitted per the usual WRED treatment. When

you enable WRED with ECN and the number of packets in the queue is between

the minimum threshold and the maximum threshold, one of the following three

scenarios can occur:

Dell(conf)#service-class wred ecn 0, 3-5, 7 backplane

service-pool wred

Configure a global buffer pool that serves as a shared buffer accessed by multiple queues when the

minimum guaranteed buffers for a queue are consumed.

The Z9500 supports four global service-pools in the egress direction. Two service pools are used—one

for lossy queues and the other for lossless (priority-based flow control (PFC)) queues. You can enable

WRED and ECN operation on the global service-pools. You can define WRED profiles and weight on each

of the global service-pools for both lossy and lossless (PFC) service-pools.

[no] buffer-pool wred {green | weight | yellow} {[pool0 number/

string] || [pool1 number/string]}

Quality of Service (QoS)

Introduced on the Z9500 switch.

Introduced on the Z9000 platform.

If the transmission endpoints are ECN-capable and traffic is congested, and the

WRED algorithm determines that the packet should be dropped based on the

drop probability, the packet is transmitted and marked so the routers know the

system is congested and can slow transmission rates.

If neither endpoint is ECN-capable, the packet may be dropped based on the

WRED drop probability. This behavior is the identical treatment that a packet

receives when WRED is enabled without ECN configured on the router.

If the network is experiencing congestion, the packet is transmitted. No further

marking is required. When you enable WRED with ECN and the number of

packets in the queue is above the maximum threshold, packets are dropped

based on the drop probability. This behavior is the identical treatment a packet

receives when WRED is enabled without ECN configured on the router.