Connectivity Guide

Next-boot Settings : Disabled
The following is Deep Buffer mode status after saving the configuration in the startup configuration:
OS10# show hardware deep-buffer-mode
Deep Buffer Mode Configuration Status
-------------------------------------------
Current-boot Settings : Disabled
Next-boot Settings : Enabled
The following is Deep Buffer mode status after the switch reloads:
OS10# show hardware deep-buffer-mode
Deep Buffer Mode Configuration Status
-------------------------------------------
Current-boot Settings : Enabled
Next-boot Settings : Enabled
Congestion avoidance
Congestion avoidance anticipates and takes necessary actions to avoid congestion. The following mechanisms avoid congestion:
● Tail drop—Packets are buffered at traffic queues. When the buffers are exhausted or reach the configured threshold,
excess packets drop. By default, OS10 uses tail drop for congestion avoidance.
● Random early detection (RED)—In tail drop, different flows are not considered in buffer utilization. When multiple hosts
start retransmission, tail drop causes TCP global re-synchronization. Instead of waiting for the queue to get filled up
completely, RED starts dropping excess packets with a certain drop-probability when the average queue length exceeds the
configured minimum threshold. The early drop ensures that only some of TCP sources slow down, which avoids global TCP
re-synchronization.
● Weighted random early detection (WRED)—This allows different drop-probabilities and thresholds for each color — red,
yellow, green — of traffic. You can configure the drop characteristics for three different flows by assigning the colors to the
flow. Assign colors to a particular flow or traffic using various methods, such as ingress policing, qos input policy-maps, and
so on.
● Explicit congestion notification (ECN)—This is an extension of WRED. Instead of dropping the packets when the
average queue length crosses the minimum threshold values, ECN marks the Congestion Experienced (CE) bit of the ECN
field in a packet as ECN-capable traffic (ECT).
1. Configure a WRED profile in CONFIGURATION mode.
OS10(config)# wred wred_prof_1
2. Configure WRED threshold parameters for different colors in WRED CONFIGURATION mode.
OS10(config-wred)# random-detect color yellow minimum-threshold 100 maximum-threshold
300 drop-probability 40
3. Configure the exponential weight value for the WRED profile in WRED CONFIGURATION mode.
OS10(config-wred)# random-detect weight 4
4. Enable ECN.
OS10(config-wred)# random-detect ecn
5. Enable WRED/ECN on a queue.
OS10(config)# class-map type queuing c1
OS10(config-cmap-queuing)# match queue 2
OS10(config-cmap-queuing)# exit
OS10(config)# policy-map type queuing p1
OS10(config-pmap-queuing)# class c1
OS10(config-pmap-c-que)# random-detect wred_prof_1
Quality of service
935