Cisco NCS 5500 Series Command Reference

random-detect
To enable random early detection (RED), use the random-detect command in policy map class configuration
mode. To remove RED, use the no form of this command.
random-detect {default|discard-class value|min-threshold [units] max-threshold [units]}
no random-detect
Syntax Description
Enables RED with default minimum and maximum thresholds.default
Discard-class based WRED (up to 2 values, which is 0 and 1).
discard-class value
Minimum threshold in number of packets. The value range of this argument is from
0 to 1073741823 in packets.
min-threshold
Maximum threshold in number of packets. The value range of this argument is from
the value of the min-threshold argument to 1073741823. When the queue length
exceeds the maximum threshold, RED drops all packets with the specified discard
class value.
max-threshold
(Optional) Units for the threshold values. Values can be:
• bytes—bytes
• gbytes—gigabytes
• kbytes—kilobytes
• mbytes —megabytes
• ms —milliseconds
• packets —packets (default)
• us —microseconds
units
Command Default
Default unit for max-threshold and min-threshold is packets.
Command Modes
Policy map class configuration
Command History
ModificationRelease
This command was introduced.Release 6.0
Usage Guidelines
The RED congestion avoidance technique takes advantage of the congestion control mechanism of TCP. By
randomly dropping packets before periods of high congestion, RED tells the packet source to decrease its
transmission rate. Assuming the packet source is using TCP, it decreases its transmission rate until all the
packets reach their destination, indicating that the congestion is cleared. You can use RED as a way to cause
TCP to slow transmission of packets. TCP not only pauses, but it also restarts quickly and adapts its transmission
rate to the rate that the network can support.
RED distributes losses in time and maintains normally low queue depth while absorbing traffic bursts. When
enabled on an interface, RED begins dropping packets when congestion occurs at a rate you select during
configuration.
Modular QoS Command Reference for Cisco NCS 5500 Series and Cisco NCS 540 Series Routers
71
Congestion Avoidance Commands
random-detect

Cisco NCS 5500 Series Specifications

General

Series	NCS 5500
Category	Network Router
Operating System	Cisco IOS XR
Product Type	Modular Router
Form Factor	Rack-mountable
Purpose	High-performance routing for service providers and large enterprises
Interface Types	Ethernet
Redundancy	Redundant power supplies and fan trays
Port Density	Varies by model; high-density configurations available
Routing Protocols	BGP, OSPF, IS-IS, MPLS
Power Supply Options	AC and DC power supplies available
Management	CLI, SNMP, NETCONF