Example for Configuring Congestion Avoidance and Congestion Management

Networking Requirements

The Switch is connected to the router through GE0/0/3; the 802.1p priorities of voice, video, and data services on the Internet are 6, 5, and 2 respectively, and these services can reach users through the router and Switch, as shown in Figure 1. The rate of inbound interface GE0/0/3 on the Switch is greater than the rates of outbound interfaces GE0/0/1 and GE0/0/2; therefore, congestion may occur on these two outbound interfaces.

To reduce the impact of network congestion and ensure bandwidth for high-priority and delay-sensitive services, set parameters based on Table 1 and Table 2.

**Table 1** Congestion avoidance parameters
Service Type	Color	Lower Threshold (%)	Upper Threshold (%)	Drop Percent
Voice	Green	80	100	10
Video	Yellow	60	80	20
Data	Red	40	60	40

**Table 2** Congestion management parameters
Service Type	CoS	WDRR
Voice	EF	0
Video	AF3	100
Data	AF1	50

Figure 1 Networking diagram for configuring congestion avoidance and congestion management

Configuration Roadmap

The configuration roadmap is as follows:

Configure the VLAN for each interface so that devices can communicate with each other.
Create and configure a DiffServ domain on the Switch, map packets of 802.1p priorities to PHBs and colors of packets, and bind the DiffServ domain to an inbound interface on the Switch.
Create a WRED drop profile on the Switch and apply the WRED drop profile on an outbound interface.
Set scheduling parameters of queues of different CoS on outbound interfaces of the Switch.

Procedure

Configure the VLAN for each interface so that the devices can communicate with each other.

<HUAWEI> system-view
[HUAWEI] sysname Switch
[Switch] vlan batch 2 5 6
[Switch] interface gigabitethernet 0/0/1
[Switch-GigabitEthernet0/0/1] port link-type trunk
[Switch-GigabitEthernet0/0/1] port trunk allow-pass vlan 2 5 6
[Switch-GigabitEthernet0/0/1] quit
[Switch] interface gigabitethernet 0/0/2
[Switch-GigabitEthernet0/0/2] port link-type trunk
[Switch-GigabitEthernet0/0/2] port trunk allow-pass vlan 2 5 6
[Switch-GigabitEthernet0/0/2] quit
[Switch] interface gigabitethernet 0/0/3
[Switch-GigabitEthernet0/0/3] port link-type trunk
[Switch-GigabitEthernet0/0/3] port trunk allow-pass vlan 2 5 6
[Switch-GigabitEthernet0/0/3] quit

Configure priority mapping based on simple traffic classification.

For the priority mapping configuration of the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-S, S5731S-H, S5732-H, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735S-S, S5735-S-I, S6720-EI, S6720S-EI, S6720-HI, S6730-H, S6730S-H, S6730-S, and S6730S-S, refer to Configuring Priority Mapping. For the priority mapping configuration of the S2720-EI, S5720-LI, S5720S-LI, S5720-SI, S5720S-SI, S5720I-SI, S5730-SI, S5730S-EI, S6720-LI, S6720S-LI, S6720-SI, and S6720S-SI, refer to Configuring Priority Mapping.

The configuration in this step is applicable to the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S.

# Create DiffServ domain ds1, map packets of 802.1p priorities 6, 5, and 2 to PHBs EF, AF3, and AF1, and color packets as green, yellow, and red.
```
[Switch] diffserv domain ds1
[Switch-dsdomain-ds1] 8021p-inbound 6 phb ef green
[Switch-dsdomain-ds1] 8021p-inbound 5 phb af3 yellow
[Switch-dsdomain-ds1] 8021p-inbound 2 phb af1 red
[Switch-dsdomain-ds1] quit
```
# Bind incoming interface GE0/0/3 on the Switch to DiffServ domain ds1.
```
[Switch] interface gigabitethernet 0/0/3
[Switch-GigabitEthernet0/0/3] trust upstream ds1
[Switch-GigabitEthernet0/0/3] trust 8021p inner
[Switch-GigabitEthernet0/0/3] quit
```

Configure congestion avoidance.

# Create drop profile wred1 on the Switch and set parameters of packets of three colors.

[Switch] drop-profile wred1
[Switch-drop-wred1] color green low-limit 80 high-limit 100 discard-percentage 10
[Switch-drop-wred1] color yellow low-limit 60 high-limit 80 discard-percentage 20
[Switch-drop-wred1] color red low-limit 40 high-limit 60 discard-percentage 40
[Switch-drop-wred1] quit

# Apply drop profile wred1 on outbound interfaces GE0/0/1 and GE0/0/2 of the Switch.

[Switch] interface gigabitethernet 0/0/1
[Switch-GigabitEthernet0/0/1] qos wred wred1
[Switch-GigabitEthernet0/0/1] qos queue 5 wred wred1
[Switch-GigabitEthernet0/0/1] qos queue 3 wred wred1
[Switch-GigabitEthernet0/0/1] qos queue 1 wred wred1
[Switch-GigabitEthernet0/0/1] quit
[Switch] interface gigabitethernet 0/0/2
[Switch-GigabitEthernet0/0/2] qos wred wred1
[Switch-GigabitEthernet0/0/2] qos queue 5 wred wred1
[Switch-GigabitEthernet0/0/2] qos queue 3 wred wred1
[Switch-GigabitEthernet0/0/2] qos queue 1 wred wred1
[Switch-GigabitEthernet0/0/2] quit

Configure congestion management.

# Set scheduling parameters of queues of different CoS on outbound interfaces GE0/0/1 and GE0/0/2 of the Switch.

[Switch] interface gigabitethernet 0/0/1
[Switch-GigabitEthernet0/0/1] qos drr
[Switch-GigabitEthernet0/0/1] qos queue 5 drr weight 0
[Switch-GigabitEthernet0/0/1] qos queue 3 drr weight 100
[Switch-GigabitEthernet0/0/1] qos queue 1 drr weight 50
[Switch-GigabitEthernet0/0/1] quit
[Switch] interface gigabitethernet 0/0/2
[Switch-GigabitEthernet0/0/2] qos drr
[Switch-GigabitEthernet0/0/2] qos queue 5 drr weight 0
[Switch-GigabitEthernet0/0/2] qos queue 3 drr weight 100
[Switch-GigabitEthernet0/0/2] qos queue 1 drr weight 50
[Switch-GigabitEthernet0/0/2] quit

Verify the configuration.

# Check the configuration of DiffServ domain ds1.

[Switch] display diffserv domain name ds1
diffserv domain name:ds1
 8021p-inbound 0 phb be green
 8021p-inbound 1 phb af1 green
 8021p-inbound 2 phb af1 red
 8021p-inbound 3 phb af3 green
 8021p-inbound 4 phb af4 green
 8021p-inbound 5 phb af3 yellow
 8021p-inbound 6 phb ef green
 8021p-inbound 7 phb cs7 green
 8021p-outbound be green map 0
......

# Check the configuration of drop profile wred1.

[Switch] display drop-profile name wred1
Drop-profile[1]: wred1
Queue depth    : default
Color     Low-limit   High-limit  Discard-percentage
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Green     80          100         10
Yellow    60          80          20
Red       40          60          40
Non-tcp   100         100         100
-----------------------------------------------------------------

Only the display information of the S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-HI, S6730-H, S6730S-H, S6730-S, and S6730S-S contains the Queue depth field.

The display information of the S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-HI, S6730-H, S6730S-H, S6730-S, and S6730S-S does not contain the Non-tcp field.

Configuration Files

Switch configuration file

#
sysname Switch
#
vlan batch 2 5 to 6
#
diffserv domain ds1
 8021p-inbound 2 phb af1 red
 8021p-inbound 5 phb af3 yellow
 8021p-inbound 6 phb ef green
#
drop-profile wred1
 color green low-limit 80 high-limit 100 discard-percentage 10
 color yellow low-limit 60 high-limit 80 discard-percentage 20
 color red low-limit 40 high-limit 60 discard-percentage 40
#
interface GigabitEthernet0/0/1
 port link-type trunk
 port trunk allow-pass vlan 2 5 to 6
 qos drr
 qos queue 1 drr weight 50
 qos queue 3 drr weight 100
 qos queue 5 drr weight 0
 qos wred wred1
 qos queue 1 wred wred1
 qos queue 3 wred wred1
 qos queue 5 wred wred1
#
interface GigabitEthernet0/0/2
 port link-type trunk
 port trunk allow-pass vlan 2 5 to 6
 qos drr
 qos queue 1 drr weight 50
 qos queue 3 drr weight 100
 qos queue 5 drr weight 0
 qos wred wred1
 qos queue 1 wred wred1
 qos queue 3 wred wred1
 qos queue 5 wred wred1
#
interface GigabitEthernet0/0/3
 port link-type trunk
 port trunk allow-pass vlan 2 5 to 6
 trust upstream ds1
 trust 8021p inner
#
return