When multiple origin servers are configured, set their priority levels so that CDN automatically fails over traffic from an unhealthy server to the next available one.
How it works
Alibaba Cloud CDN supports three types of origin servers: Object Storage Service (OSS) domain names, IP addresses, and origin domain names.
When the origin server type is IP or Origin Domain Name, each server is assigned a priority: Primary or Secondary. CDN routes back-to-origin traffic based on these priorities:
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Route to the highest priority. CDN directs all back-to-origin traffic to Primary origin servers.
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Distribute among same-priority servers. If multiple servers share the same priority, CDN polls them with equal probability. For example, if three Primary servers are configured, each server receives 30 requests out of a total of 90.
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Fail over on health check failure. If a Primary server fails its health check three consecutive times, CDN redirects all traffic to Secondary servers.
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Restore after recovery. When the failed server passes a subsequent health check, CDN marks it as available and restores its original priority.
Health checks
Active Layer 4 health checks run against each origin server every 2.5 seconds.
Usage notes
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Priority settings are available only when the origin server type is IP or Origin Domain Name. OSS domain names do not support priority configuration.
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Live streaming acceleration does not support origin server settings.
Procedure
Prerequisites
Before you begin, make sure that you have:
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At least two origin servers configured for the domain name. For more information, see Configure an origin host.
Set origin server priority
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Log on to the ApsaraVideo VOD console.
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In the left-side navigation pane, choose Configuration Management.
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Click CDN Configuration > Domain Names.
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Find the target domain name and click Configure.
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Click Basic Configuration . In the Source Station Information section, click Modify.
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Set the origin server type, address, port, and priority.
Port configuration:
Item
Description
Custom port availability
Available after the origin server IP addresses are added to the whitelist. Valid values: 0 to 65535.
Adopt protocol restriction
If the static or dynamic protocol is set to Adopt, custom ports are not supported.
OpenAPI with Adopt
If you use OpenAPI to set the origin protocol policy to Adopt, make sure that both the origin protocol and the custom port function correctly.
Custom port override
If you set an origin protocol such as HTTP or HTTPS and a custom port, back-to-origin requests use the custom port, regardless of other port settings in the console.
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Click OK.
Billing
| Origin type | Billing method |
|---|---|
| IP or Origin Domain Name | Charged at internet traffic rates |
| OSS domain name | Charged at internal network rates. For more information, see OSS pricing. |
| Origin Domain Name set to an OSS domain name | Charged at internet traffic rates |