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| Title | Size | Download |
|---|---|---|
| 03-MPLS QoS configuration | 65.66 KB |
Configuring MPLS QoS
Overview
In the area of QoS, in order to provide the support for differentiated services (DiffServ) as IP does, MPLS uses three bits analogous to IP precedence, called "EXP bits," to carry class-of-service information. With the EXP bits, MPLS QoS is achieved to identify different traffic flows and implement differentiated services, guaranteeing low delay and low packet loss ratio for critical service traffic, such as voice and video traffic. For more information about MPLS, see MPLS Configuration Guide.
MPLS QoS supports Committed Access Rate (CAR) and priority marking. MPLS QoS provides the following functions:
· Classify traffic on the PE to apply differentiated QoS strategies for different traffic classes. For example, MPLS QoS can organize packets with EXP value 1 into a class and packets with EXP value 2 into another class, and then perform traffic policing and priority marking for each class of packets.
· When a PE labels a packet, it maps the IP precedence to the EXP field of the label. In this way, the class information carried in the IP header is carried in the label.
The EXP field in an MPLS label is processed following these rules:
· The device re-sets the EXP field of only the topmost label.
· During label encapsulation, the ToS field of the IP packet is directly changed into the EXP field of the MPLS label.
· The EXP field remains unchanged when label swapping is performed.
· During a label push operation, the EXP field of the newly pushed outer label inherits the EXP field of the inner label.
· After a label pop operation, if the packet is still an MPLS packet, the EXP field of the popped label is not copied to the inner label. If the packet is an IP packet, the EXP field of the popped label is not copied to the ToS field of the IP packet.
Configuration procedure
Before configuring MPLS QoS, complete basic MPLS configuration. For more information about basic MPLS configurations, see MPLS Configuration Guide.
In an MPLS network, you can adjust the priority of an MPLS traffic flow by marking its EXP value. For more information about priority marking, see "Configuring priority marking."
To configure the MPLS priority marking action for an MPLS traffic class:
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Create a traffic class and enter traffic class view. |
traffic classifier classifier-name [ operator { and | or } ] |
By default, no traffic class is created. |
|
3. Configure match criteria for the traffic class. |
· if-match mpls-exp exp-value&<1-8> · if-match second-mpls-exp exp-value&<1-8> · if-match mpls-label { label-value&<1-8> | label-value1 to label-value2 } · if-match second-mpls-label { label-value&<1-8> | label-value1 to label-value2 } |
Use at least one command. By default, no match criteria are configured. The match criteria apply only to MPLS packets. |
|
4. Return to system view. |
quit |
N/A |
|
5. Create a traffic behavior and enter traffic behavior view. |
traffic behavior behavior-name |
By default, no traffic behavior is created. |
|
6. Configure an EXP marking action in the traffic behavior. |
remark mpls-exp exp-value |
By default, no EXP marking action is configured. |
|
7. Return to system view. |
quit |
N/A |
|
8. Create a QoS policy and enter QoS policy view. |
qos policy policy-name |
By default, no QoS policy is created. |
|
9. Associate the traffic class with the traffic behavior in the QoS policy. |
classifier classifier-name behavior behavior-name |
By default, no traffic behavior is associated with a traffic class. |
|
10. Return to system view. |
quit |
N/A |
|
11. Enter interface view. |
interface interface-type interface-number |
N/A |
|
12. Apply the QoS policy. |
You can apply a QoS policy in the following approaches: · Apply the QoS policy to an interface. · Apply the QoS policy to a VLAN. · Apply the QoS policy globally. |
Use one of the approaches. By default, no QoS policy is applied. |
