QoS Policy
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Feature Overview
Direct Connect Port QoS Scheduling is a port-level traffic priority scheduling capability provided by Direct Connect. It is implemented by configuring flow queues on the physical Direct Connect port. This configuration assigns egress traffic to queues and schedules its priority based on DSCP values, ensuring the prioritized transmission of critical business traffic during bandwidth congestion.
When multiple services share the same physical dedicated line, burst traffic can cause packet loss or latency for critical services, such as real-time video and core trading systems. QoS scheduling defines differentiated forwarding priorities and bandwidth allocation ratios for traffic with different DSCP values, ensuring that high-priority services obtain the required bandwidth.
This document guides you to capture service traffic using matching policies in the VPC console, and to create a QoS policy to queue and schedule the traffic. This process implements bandwidth guarantee and priority scheduling for different services on the physical Direct Connect port.
Note:
1. QoS scheduling applies only to egress (outbound) traffic. For ingress traffic, scheduling must be performed by the customer on relevant IDC equipment.
2. This feature is currently in a limited release. To use it, submit a ticket to apply.
How It Works
Port QoS scheduling is implemented through the following process:
1. DSCP Marking Identification: The port reads the DSCP value in the IP header of a packet (marked by the Direct Connect gateway or by the customer's CVM).
2. Flow queue matching: Traffic is allocated to the corresponding flow queue based on its DSCP value.
3. Priority scheduling and forwarding: High-priority queue traffic is forwarded first. Standard queues are allocated the remaining bandwidth according to the configured bandwidth ratio.
Core Concepts
Term | Description |
QoS policy | A collection of flow queue configurations that takes effect upon being bound to a physical dedicated line and clicked. Ports and the QoS policy have an N:1 relationship, and multiple dedicated lines can share the same policy. |
Flow queue | A sub-item under the QoS policy that defines priority, bandwidth allocation ratio, and traffic matching rules. |
High-priority queue | A high-priority queue where traffic is scheduled and forwarded preferentially. A single QoS policy supports a maximum of one high-priority queue. |
Standard queue | A queue that allocates remaining bandwidth according to a specified ratio. A single QoS policy supports a maximum of four standard queues. |
Remark DSCP | Remarks the DSCP value of packets after port forwarding, enabling downstream devices to execute policies based on the new DSCP value. |
Use Limits
Limit | Description |
Effective Direction | Only applies to outbound (egress) traffic. |
Supported Dedicated Line Types | Supports dedicated physical connections (including dedicated Agile onto Cloud of Direct Connect). Does not support shared dedicated tunnels. |
Relationship Between Port and QoS Policy | N:1 (Multiple dedicated lines can be bound to the same QoS policy, and each dedicated line can be bound to only one policy). |
Number of high-priority queues | A single QoS policy supports a maximum of 1. |
Number of standard queues | A single QoS policy supports a maximum of 4. |
Maximum number of traffic matching policies per QoS | A maximum of 5. |
DSCP value range | 0 - 63. |
Bandwidth allocation for standard queues | The sum of the bandwidth ratios for all standard queues does not exceed 99%. |
Mutual exclusivity with channel bandwidth throttling | After a QoS policy is enabled, the bandwidth rate limiting for all dedicated tunnels under this dedicated line automatically becomes invalid, and the tunnel bandwidth equals the port bandwidth. |
Mutual exclusivity of traffic matching policies | A traffic matching policy cannot be bound to both Direct Connect gateway DSCP marking and port rate limiting simultaneously. |
Note:
1G and 10G ports are not supported.
Prerequisites
You have successfully applied for a physical dedicated line, and its status is Operational. To apply for a physical dedicated line, see Apply for a Physical Dedicated Line.
You have been granted access to the allowlist for the QoS feature's limited release. To use it, submit a ticket to apply.
The traffic has been marked with DSCP (by the Direct Connect gateway or by the CVM itself).
Operation Steps
Step 1: Configure a Traffic Matching Policy
A traffic matching policy is used to define the characteristics of business traffic that requires DSCP marking.
1. Log in to the VPC console.
2. Select Traffic Matching Policy in the left sidebar.
3. Click Create and configure the following parameters:
Parameter | Required | Description |
Name | Yes | The name of the matching policy, which facilitates identification and management. |
Priority | Yes | Valid value range: 1 - 100. A smaller value indicates a higher priority. Each network element preferentially matches the policy with a higher priority. |
Description | No | The remarks for the matching policy. It is recommended to fill in the corresponding business purpose. |
4. Click OK to complete the traffic matching rule creation.
5. Configure matching rules.
In the matching policy list, click the ID/Name of the target policy to go to the Matching Rules tab. Click Add Rule, enter matching conditions for the business data packets, and after filling in the following parameters, click OK.
Parameter | Required | Description |
Protocol | Yes | The protocol type for capturing traffic packets. Supports TCP, UDP, and others. |
Source IP range | No | The source IP address CIDR block of data packets, for example, 10.0.0.0/24. If not specified, any source IP address is matched by default. |
Target IP range | No | The target IP address CIDR block of data packets, for example, 10.0.0.0/24. If not specified, any destination IP address is matched by default. |
Source port | No | Valid range: 1 - 65535. If not specified, any source port is matched by default. |
Destination port | No | Valid range: 1 - 65535. If not specified, any destination port is matched by default. |
DSCP | No | The inner-layer DSCP of packets, with a valid range of 0 - 63. It is used to match packets that already carry a specified DSCP. If left blank, all packets are matched. |
Remark | No | The description information of the matching rule. |
Note:
A traffic matching policy is a VPC-side resource and can be referenced in Direct Connect gateway DSCP marking and QoS flow queues.
Step 2: Create a QoS Policy
1. Log in to the Direct Connect console.
2. Select QoS Policy in the left sidebar.
3. Click Create. Configure the basic information and flow queue information. To add more queues, click Add Row. After confirming that all parameters are filled in, click OK.
Parameter | Description |
QoS name | A custom policy name (the system automatically generates a QoS policy ID). |
Flow queue name | A custom queue name (the system automatically generates a flow queue ID). |
Priority | Select high-priority queues or standard queues. |
Bandwidth allocation ratio | Only applicable to standard queues. Value range: 1 - 99 (the sum for all standard queues must not exceed 99%). |
Traffic matching policy | Select from a drop-down list to bind created traffic matching policies (a maximum of 5 policies can be bound per QoS). Attention: QoS scheduling does not recognize the priority parameters in the traffic matching policy and assigns queues solely based on DSCP values. |
Remark DSCP | Optional. Remap the DSCP value for traffic passing through this queue. The value ranges from 0 to 63. |
Note:
1. High-priority queues do not require a bandwidth allocation ratio to be configured. Their bandwidth is not limited, and their traffic is forwarded with priority.
2. Within the same QoS policy, different queues cannot be bound to the same traffic matching policy.
3. When you click OK, the system checks whether the total bandwidth allocation for standard queues exceeds 99%.
Step 3: Bind a Physical Direct Connect
Bind the QoS policy to the physical Direct Connect.
1. On the QoS Policy list page, click the target policy ID to go to its details page.
2. Select the Associated Direct Connect tab, click Bind Connection, select the physical Direct Connect to be bound in the pop-up window, and then click OK.
Note:
1. Only display physical Direct Connects that are not bound to a QoS policy.
2. After binding, the bandwidth parameters for all dedicated tunnels under the Direct Connect are automatically set to the port bandwidth and cannot be adjusted individually.
3. Direct Connect types include My Direct Connect and Agile onto Cloud of Direct Connect (supported only by exclusive Agile onto Cloud of Direct Connect).
Step 4: Enable a QoS Policy
1. After the flow queue configuration and its association with the Direct Connect are completed, click Enable in the Actions column of the QoS Policy list.
2. In the Enable QoS Policy confirmation pop-up window, verify the information and click OK. The QoS policy then takes effect.
Step 5: Manage QoS Policies
Disabling a QoS Policy
1. On the QoS Policy list page, locate the target policy and click Disable in the Actions column.
Attention:
After the QoS policy is disabled, the scheduling capability becomes invalid.
2. In the confirmation pop-up window, select the confirmation impact description and click OK.
Deleting a QoS Policy
Attention:
A QoS policy can be deleted only when it is in the Disabled state and is not bound to any physical Direct Connect.
1. On the QoS Policy list page, locate the target policy and click Delete in the Actions column.
2. In the confirmation pop-up window, click OK.
Managing Flow Queues
On the Flow Queue tab of the QoS Policy details page, the following operations are supported:
Operation | Description |
Creating a flow queue | Supports creating flow queues. Attention: The number of priority queues for a single QoS is subject to a quota limit. |
Modifying a flow queue | Supports modifying priority, bandwidth ratio, traffic matching policy, and Remark DSCP. |
Deleting a flow queue | Cannot be configured after deletion. Please note. |
Viewing Monitoring Data | View the bandwidth rate and packet loss rate monitoring data of this queue. |
Unbinding a Physical Direct Connect
1. On the QoS Policy details page, select the Associated Direct Connect tab.
2. Select the physical Direct Connect to be unbound and click Unbind Direct Connect.
3. In the confirmation pop-up window, click Confirm.
Note:
After unbinding, the QoS policy will no longer take effect on the Direct Connect, and the channel bandwidth throttling will be restored.
Impact on Dedicated Tunnels
After a physical Direct Connect is bound to and enabled with a QoS policy, all dedicated tunnels under that Direct Connect are subject to the following impacts:
Affected Item | Description |
Existing Channels | The bandwidth parameter is locked to the port bandwidth value and cannot be modified. |
Create a Channel | The bandwidth is automatically populated with the port bandwidth and cannot be adjusted by users. |
Channel Throttling | During QoS activation, the tunnel-level bandwidth rate limiting feature becomes invalid. |
Monitoring and Alarms
The QoS policy supports the following monitoring metrics:
Metric Name | Description | Unit |
Average bandwidth rate of QoS flow queue | Outbound data transmission rate per second through the flow queue | bps |
Average packet loss rate of QoS flow queue | Number of outbound packets lost per second through the flow queue | pps |
Application Scenario Examples
Multi-Service Bandwidth Guarantee
An enterprise uses a single 10G dedicated line to simultaneously carry three types of services: video conferencing, ERP system, and data backup. Using a QoS policy, video conferencing is assigned to a high-priority queue for preferential forwarding, while ERP and data backup are configured with standard queues, allocating the remaining bandwidth in a 60%:40% ratio. This ensures that video conferencing is not interrupted by burst traffic from data backup.
Multi-Service Tiered Transmission for IDC
An AI training cluster and an office OA system are deployed in the customer's IDC, with results transmitted back to the cloud via a dedicated line. AI training traffic is high-bandwidth and low-priority, while office traffic is low-bandwidth and high-priority. Differentiated scheduling is achieved through a QoS policy.
FAQs
Why Can't I Modify the Tunnel Bandwidth After the QoS Policy Is Enabled?
The QoS policy performs traffic scheduling at the port level. Channel-level bandwidth throttling is mutually exclusive with QoS scheduling. After QoS is enabled, the bandwidth of all channels automatically equals the port bandwidth, and traffic allocation is uniformly managed by the QoS policy.
Can a Direct Connect Be Bound to Multiple QoS Policies?
No. Each physical Direct Connect can be bound to only one QoS policy, but a single policy can be shared by multiple Direct Connects.
Can the DSCP Value Tagged by CVM Be Recognized by the Port?
Yes. As long as a packet carries a valid DSCP value in its IP address header when it arrives at the physical Direct Connect port, the port can perform flow queue matching and scheduling based on that value.
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