Contents

Introduction· 1

Prerequisites· 1

Example: Configuring congestion avoidance and queue scheduling· 1

Network configuration· 1

Analysis· 2

Applicable hardware and software versions· 3

Procedures· 3

Verifying the configuration· 5

Configuration files· 6

 

Introduction

This document provides examples for configuring congestion avoidance and queue scheduling profiles.

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of congestion avoidance and queue scheduling profiles.

Example: Configuring congestion avoidance and queue scheduling

Network configuration

As shown in Figure 1, three types of traffic come from the Internet to the device through the gateway.

·     Voice traffic—Transmitted in VLAN 6 and carries 802.1p priority 6.

·     Video traffic—Transmitted in VLAN 4 and carries 802.1p priority 4.

·     Data traffic—Transmitted in VLAN 2 and carries 802.1p priority 2.

Configure congestion avoidance and queue scheduling on the device to meet the following requirements:

·     The voice traffic, video traffic, and data traffic are scheduled in the ratio of 1:2:2 when congestion occurs.

·     WRED drop is used when serious congestion occurs.

Figure 1 Network diagram

 

Analysis

To configure congestion avoidance and queue scheduling, you must perform the following tasks:

·     To assign different types of traffic to different queues, configure the inbound interface to trust the 802.1p priority in packets.

·     To schedule the three types of traffic in the ratio of 1:2:2, assign their queues to one WRR group and configure weights for these queues.

·     To minimize performance degradation for different types of traffic, use the drop parameters in Table 1.

Table 1 Drop parameters

Traffic type	Packet color	Lower limit	Upper limit	Drop probability
Voice	Yellow	1000	1500	3%
	Red	500	1000	30%
Video	Yellow	1000	1500	2%
	Red	500	1000	20%
Data	Yellow	1000	1500	1%
	Red	500	1000	10%

 

Applicable hardware and software versions

The following matrix shows the hardware and software versions to which this configuration example is applicable:

 

Hardware	Software version
S6550X-HI switch series	Release 1116 and later
S6880 switch series	Release 1116 and later
S9820-8M switch	Release 1116 and later
S9855 switch series	Release 9126 and later
S9825 switch series	Release 9126 and later

 

Procedures

1.     Allow VLANs for different types of traffic to pass through:

# Create three VLANs .

<Device> system-view

[Device] vlan 2

[Device-vlan2] quit

[Device] vlan 4

[Device-vlan4] quit

[Device] vlan 6

[Device-vlan6] quit

# Assign interfaces to VLANs.

[Device] interface hundredgige 2/0/1

[Device-HundredGigE2/0/1] port link-type trunk

[Device-HundredGigE2/0/1] port trunk permit vlan 2 4 6

[Device-HundredGigE2/0/1] quit

[Device] interface twenty-fivegige 1/0/1

[Device-Twenty-FiveGigE1/0/1] port link-type trunk

[Device-Twenty-FiveGigE1/0/1] port trunk permit vlan 2 4 6

[Device-Twenty-FiveGigE1/0/1] quit

[Device] interface twenty-fivegige 1/0/2

[Device-Twenty-FiveGigE1/0/2] port link-type trunk

[Device-Twenty-FiveGigE1/0/2] port trunk permit vlan 2 4 6

[Device-Twenty-FiveGigE1/0/2] quit

2.     Configure interface HundredGigE 2/0/1 to trust the 802.1p priority in packets.

[Device] interface hundredgige 2/0/1

[Device-HundredGigE2/0/1] qos trust dot1p

[Device-HundredGigE2/0/1] quit

[Device] interface hundredgige 2/0/1

[Device- interface hundredgige 2/0/1] qos trust auto

[Device-HundredGigE2/0/1] quit

3.     Configure WRR on Twenty-FiveGigE 1/0//1 and Twenty-FiveGigE 1/0//2:

# Display the 802.1p-to-local precedence map to determine the local precedence for each type of traffic.

[Device] display qos map-table inbound dot1p-lp

MAP-TABLE NAME: dot1p-lp   TYPE: pre-define

IMPORT  :  EXPORT

   0    :    2

   1    :    0

   2    :    1

   3    :    3

   4    :    4

   5    :    5

   6    :    6

   7    :    7

# Enable weight-based WRR on Twenty-FiveGigE 1/0/1.

[Device] interface twenty-fivegige 1/0/1

[Device-Twenty-FiveGigE1/0/1] qos wrr weight

# Configure the weights of queue 1 (for data traffic), queue 4 (for video traffic), and queue 6 (for voice traffic) as 2, 2, and 1, respectively.

[Device-Twenty-FiveGigE1/0/1] qos wrr 1 group 1 weight 2

[Device-Twenty-FiveGigE1/0/1] qos wrr 4 group 1 weight 2

[Device-Twenty-FiveGigE1/0/1] qos wrr 6 group 1 weight 1

[Device-Twenty-FiveGigE1/0/1] quit

# Enable weight-based WRR on Twenty-FiveGigE 1/0/2.

[Device] interface twenty-fivegige 1/0/2

[Device-Twenty-FiveGigE1/0/2] qos wrr weight

# Configure the weights of queue 1 (for data traffic), queue 4 (for video traffic), and queue 6 (for voice traffic) as 2, 2, and 1, respectively.

[Device-Twenty-FiveGigE1/0/2] qos wrr 1 group 1 weight 2

[Device-Twenty-FiveGigE1/0/2] qos wrr 4 group 1 weight 2

[Device-Twenty-FiveGigE1/0/2] qos wrr 6 group 1 weight 1

[Device-Twenty-FiveGigE1/0/2] quit

4.     Configure congestion avoidance:

# Configure a WRED table.

[Device] qos wred queue table droppolicy

[Device-wred-table-droppolicy] queue 6 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 3

[Device-wred-table-droppolicy] queue 6 drop-level 2 low-limit 500 high-limit 1000 discard-probability 30

[Device-wred-table-droppolicy] queue 4 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 2

[Device-wred-table-droppolicy] queue 4 drop-level 2 low-limit 500 high-limit 1000 discard-probability 20

[Device-wred-table-droppolicy] queue 1 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 1

[Device-wred-table-droppolicy] queue 1 drop-level 2 low-limit 500 high-limit 1000 discard-probability 10

[Device-wred-table-droppolicy] quit

# Apply the WRED table to interfaces Twenty-FiveGigE 1/0/1 and Twenty-FiveGigE 1/0/2.

[Device] interface twenty-fivegige 1/0/1

[Device-Twenty-FiveGigE1/0/1] qos wred apply droppolicy

[Device-Twenty-FiveGigE1/0/1] quit

[Device] interface twenty-fivegige 1/0/2

[Device-Twenty-FiveGigE1/0/2] qos wred apply droppolicy

[Device-Twenty-FiveGigE1/0/2] quit

Verifying the configuration

# Verify the WRR configuration on interfaces Twenty-FiveGigE 1/0/1 and Twenty-FiveGigE 1/0/2.

[Device] display qos queue wrr interface

Interface: Twenty-FiveGigE1/0/1

 Output queue: Weighted Round Robin queuing

 Queue ID     Queue name     Group     Byte count

 ---------------------------------------------------

 0            be             1         1

 1            af1            1         2

 2            af2            1         3

 3            af3            1         4

 4            af4            1         2

 5            ef             1         9

 6            cs6            1         1

 7            cs7            1         15

Interface: Twenty-FiveGigE1/0/2

 Output queue: Weighted Round Robin queuing

 Queue ID     Queue name     Group     Byte count

 ---------------------------------------------------

 0            be             1         1

 1            af1            1         2

 2            af2            1         3

 3            af3            1         4

 4            af4            1         2

 5            ef             1         9

 6            cs6            1         1

 7            cs7            1         15

# Display the WRED table configuration.

Table name: droppolicy                                                         

Table type: Queue based WRED                                                   

QID   gmin  gmax  gprob  ymin  ymax  yprob  rmin  rmax  rprob  exponent  ECN   

----------------------------------------------------------------------------   

0     100   1000  10     100   1000  10     100   1000  10     9         N     

1     100   1000  10     1000  1500  1      500   1000  10     9         N     

2     100   1000  10     100   1000  10     100   1000  10     9         N     

3     100   1000  10     100   1000  10     100   1000  10     9         N     

4     100   1000  10     1000  1500  2      500   1000  20     9         N     

5     100   1000  10     100   1000  10     100   1000  10     9         N     

6     100   1000  10     1000  1500  3      500   1000  30     9         N     

7     100   1000  10     100   1000  10     100   1000  10     9         N    

Configuration files

#

vlan 1

#

vlan 2

#

vlan 4

#

vlan 6

#

qos wred queue table droppolicy

 queue 1 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 1

 queue 1 drop-level 2 low-limit 500 high-limit 1000 discard-probability 10

 queue 4 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 2

 queue 4 drop-level 2 low-limit 500 high-limit 1000 discard-probability 20

 queue 6 drop-level 1 low-limit 1000 high-limit 1500 discard-probability 3

 queue 6 drop-level 2 low-limit 500 high-limit 1000 discard-probability 30

#

interface Twenty-FiveGigE1/0/1

 port link-mode bridge

 port link-type trunk

 port trunk permit vlan 1 to 2 4 6

 qos byte-count

 qos wrr af1 group 1 byte-count 2

 qos wrr af4 group 1 byte-count 2

 qos wrr cs6 group 1 byte-count 1

 qos wred apply droppolicy

#

interface Twenty-FiveGigE1/0/2

 port link-mode bridge

 port link-type trunk

 port trunk permit vlan 1 to 2 4 6

 qos wrr byte-count

 qos wrr af1 group 1 byte-count 2

 qos wrr af4 group 1 byte-count 2

 qos wrr cs6 group 1 byte-count 1

 qos wred apply droppolicy

#

interface HundredGigE2/0/1

 port link-mode bridge

 port link-type trunk

 port trunk permit vlan 1 to 2 4 6

#

return