Login
- Table of Contents
- Related Documents
-
| Title | Size | Download |
|---|---|---|
| 03-EPON QoS configuration | 111.05 KB |
Contents
Restrictions and guidelines: EPON QoS configuration
Setting DBA parameters for an OLT
Configuring ONU bandwidth allocation and related parameters
Configuring congestion management for uplink ONU traffic
Configuring CoS-to-local priority mappings on an ONU interface or RONU interface
Configuring priority marking on a UNI
Configuring traffic policing on a UNI
Configuring EPON QoS
EPON QoS overview
Figure 1 shows the QoS model of the EPON system.
|
|
NOTE: This document describes only QoS features supported when the device acts as an OLT. For information about other QoS features, see "Appendix Support for non-EPON features." |
An OLT supports remotely configuring the following QoS features for ONUs:
· ONU bandwidth allocation
Allocate uplink and downlink bandwidth based on different terminal service requirements to realize efficient bandwidth utilization.
· Congestion management for uplink ONU traffic
By configuring Service Level Agreement (SLA) attributes, you can remotely manage the fixed bandwidth, guaranteed bandwidth, and best-effort bandwidth for each queue on an ONU. During each DBA scheduling cycle, the ONU granularly manages the uplink bandwidth for each queue according to the uplink traffic queue scheduling configuration of the ONU and the DBA configuration on the OLT.
The following queue scheduling modes are supported:
¡ SP—Strict priority queueing, which classifies the eight output queues into eight classes, 7, 6, 5, 4, 3, 2, 1, and 0, in descending order of priority.
¡ WRR—Weighted round robin, which schedules queues according to their weights in a round robin way. WRR guarantees certain service time for each queue.
¡ SP+WRR—Uses SP and WRR together to schedule queues.
For more information about SP and WRR, see hardware congestion management configuration in ACL and QoS Configuration Guide.
· CoS-to-local priority mapping on ONU interfaces and RONU interfaces
When an ONU receives downlink traffic from an ONU or RONU interface of an OLT, the ONU assigns the traffic to different output queues based on CoS-to-local priority mappings.
· UNI priority marking
Priority marking enables an ONU to perform the following operations on packets received from a UNI:
a. Classifies packets received from a UNI into multiple classes based on information of the packets, such as MAC addresses and IP addresses.
b. Applies different priority mapping policies to packets of different classes.
· UNI traffic policing
Traffic policing allows ONUs to evaluate traffic and limit the traffic rate. Traffic evaluation is implemented through the token bucket mechanism.
The token bucket mechanism evaluates traffic by checking the number of tokens in the bucket.
¡ If the number of tokens in the bucket is enough for forwarding the packets, the traffic conforms to the specification (called conforming traffic).
¡ If the number of tokens is not enough, the traffic does not conform to the specification (called excess traffic).
A token bucket has the following parameters:
¡ Committed information rate (CIR)—Rate at which tokens are put into the bucket, or the permitted average rate of traffic.
¡ Committed burst size (CBS)—Burst size or the capacity of the token bucket. It is the maximum traffic size permitted in each burst. The burst size must be greater than the maximum packet size.
¡ Excess Burst Size (EBS). For more information, see ACL and QoS Configuration Guide.
¡ Peak Information Rate (PIR). For more information, see ACL and QoS Configuration Guide.
Restrictions and guidelines: EPON QoS configuration
In an EPON system, support of ONUs for EPON QoS varies by ONU model and software version.
EPON features are supported only on the default MDC. For more information about MDCs, see Virtual Technologies Configuration Guide.
All tasks in this chapter are optional. Choose tasks as needed.
Setting DBA parameters for an OLT
About DBA parameters
An OLT uses dynamic bandwidth allocation (DBA) to adjust the uplink bandwidth of individual ONUs in real time based on the traffic status of the ONUs.
DBA is implemented through a request-response mechanism as follows:
1. An OLT obtains the traffic information of ONUs from the bandwidth requests (REPORT messages) received from ONUs.
2. The OLT uses a bandwidth allocation algorithm to calculate the bandwidth to be allocated for this cycle within the uplink bandwidth range for each ONU.
3. The OLT sends the bandwidth allocation results to the ONUs through bandwidth authorization (general GATE messages).
DBA ensures that uplink data sent by ONUs will not conflict with each other. For more information about uplink bandwidth allocation configuration, see "Configuring uplink bandwidth allocation."
Restrictions and guidelines
Incorrect DBA settings might interrupt services. Make sure you are fully aware of the impact of this task when you perform it on a live network.
Configuring ONU discovery parameters
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter OLT interface view. |
interface olt interface-number |
N/A |
|
3. Set ONU discovery parameters. |
dba-parameters { discovery-frequency frequency | discovery-length length } * |
By default, an OLT interface initiates ONU discovery at an interval of 500 milliseconds, and each ONU discovery process lasts for 3076 TQ. The unit of the frequency argument is 0.1 millisecond. The unit of the length argument is time quantum (TQ). 1 TQ is equal to 16 ns. |
Configuring ONU REPORT message settings
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU interface view. |
interface onu interface-number |
N/A |
|
3. Set the number of queue sets that ONU REPORT messages support. |
dba-report queue-set-number queue-set-number |
By default, ONU REPORT messages support two queue sets. |
|
4. Configure the threshold for a queue. |
dba-report queue-set-id queue-set-id queue-id queue-id { active | inactive } threshold threshold-value |
The default thresholds are as follows: · 0 for queues 1 through 3, and the threshold is activated. · 65535 for queues 4 and 5, and the threshold is activated. · 0 for queues 6 through 8, and the threshold is not activated. |
Configuring QoS for an ONU
Configuring ONU bandwidth allocation and related parameters
Restrictions and guidelines
You can set the maximum uplink bandwidth for a single ONU interface separately in ONU interface view or for all ONU interfaces in bulk in FTTH view. When both types of configuration exist, the configuration for a single ONU interface takes effect.
Configuring downlink bandwidth allocation for an ONU interface
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU interface view. |
interface onu interface-number |
N/A |
|
3. Enable the downlink bandwidth allocation policy. |
bandwidth-downstream policy enable |
By default, the downlink bandwidth allocation policy is disabled on an ONU interface. Downlink bandwidth limits take effect only when the downlink bandwidth allocation policy is enabled. |
|
4. Configure the downlink bandwidth limits. |
bandwidth-downstream { max-bandwidth bandwidth | max-burstsize burstsize } * |
By default, the maximum downlink bandwidth is 999994 kbps (9999940 kbps for 10G-EPON cards), and the maximum downlink burst buffer is 4194240 bytes. The downlink bandwidth limits take effect only on known unicast packets. |
Configuring uplink bandwidth allocation for a single ONU interface
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU interface view. |
interface onu interface-number |
N/A |
|
3. Configure the uplink bandwidth limits. |
upstream-sla { fixed-bandwidth fixed-value | minimum-bandwidth min-value | maximum-bandwidth max-value | weight weight-value } * |
By default, the fixed uplink bandwidth is 0 kbps, the minimum uplink bandwidth is 2048 kbps, the maximum uplink bandwidth is 23552 kbps, and the bandwidth allocation weight is 1. |
Configuring the maximum uplink bandwidth for all ONU interfaces
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter FTTH view. |
ftth |
N/A |
|
3. Configure the maximum uplink bandwidth for all ONU interfaces. |
· In standalone mode: · In IRF mode: |
By default, the maximum uplink bandwidth is 23552 kbps for ONU interfaces. |
Configuring congestion management for uplink ONU traffic
Restrictions and guidelines
In SP+WRR mode, as a best practice, use the SP queue scheduling for packets with priority values 6 and 7 (for example, network control protocol packets and TDM packets).
In SP mode, you must configure a minimum of one SP queue.
In WRR mode, you must configure a minimum of one WRR queue.
In SP+WRR mode, you must configure a minimum of one SP queue and one WRR queue.
On an ONU, the sum of WRR queue weights must be 100.
Configuration procedure
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU or RONU interface view. |
· Enter ONU interface view. · Enter RONU interface view. |
N/A |
|
3. Configure the uplink traffic queue scheduling mode for the ONU. |
service-sla mode { sp | wrr | sp-wrr high-priority-boundary boundary-queue-id } [ cycle-length length ] |
By default, no uplink traffic queue scheduling mode is configured for an ONU. In SP+WRR mode, queues with IDs as boundary-queue-id and higher are configured as SP queues, and queues with IDs smaller than boundary-queue-id are configured as WRR queues. The cycle-length keyword specifies the DBA polling cycle and is only for administrator use. As a best practice, do not configure this keyword as a common user. |
|
4. Configure the uplink traffic queue parameters. |
service-sla queue queue-id { sp | wrr weight weight } [ [ fixed-packet-size fixed-packet-size ] fixed-bandwidth fixed-bandwidth ] guaranteed-bandwidth guaranteed-bandwidth best-effort-bandwidth best-effort-bandwidth |
By default, no uplink traffic queue parameters are configured for an ONU. |
|
5. Apply the uplink traffic queue scheduling configuration to the ONU. |
service-sla apply |
To modify the queue scheduling mode or queue parameters after executing this command, first execute the undo service-sla apply command. |
Configuring CoS-to-local priority mappings on an ONU interface or RONU interface
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU or RONU interface view. |
· Enter ONU interface view. · Enter RONU interface view. |
N/A |
|
3. Configure CoS-to-local priority mappings on the ONU or RONU interface. |
qos cos-local-precedence-map cos0 cos1 cos2 cos3 cos4 cos5 cos6 cos7 |
Table 1 shows default CoS-to-local priority mappings. |
Table 1 Default CoS-to-local priority mappings
|
CoS priority |
Local precedence |
|
0 |
0 |
|
1 |
0 |
|
2 |
1 |
|
3 |
1 |
|
4 |
2 |
|
5 |
2 |
|
6 |
3 |
|
7 |
3 |
Configuring priority marking on a UNI
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU or RONU interface view. |
· Enter ONU interface view. · Enter RONU interface view. |
N/A |
|
3. Configure priority marking on a UNI. |
uni uni-number classification-marking index index queue qid priority priority { { selector operator matched-value } & <1-4> | always-match | never-match } |
By default, priority marking is not configured on a UNI. Do not use this command together with the qos trust dscp command. For more information about the qos trust command, see ACL and QoS Command Reference. |
Configuring traffic policing on a UNI
|
Step |
Command |
Remarks |
|
1. Enter system view. |
system-view |
N/A |
|
2. Enter ONU or RONU interface view. |
· Enter ONU interface view. · Enter RONU interface view. |
N/A |
|
3. Configure uplink traffic policing on a UNI. |
uni uni-number port-policy inbound { bucket-depth bucket-depth-value | cir cir-value | extra-burst-size extra-burst-size-value } * |
The bucket-depth bucket-depth-value option sets the CBS, and the extra-burst-size extra-burst-size-value option sets the EBS. By default, the CBS is 1522 bytes, the CIR is 0 kbps, and the EBS is 0 bytes. |
|
4. Configure downlink traffic policing on a UNI. |
uni uni-number port-policy outbound cir cir-value [ pir pir-value ] |
By default, the CIR is 0 kbps and the PIR is 0 kbps. |
