Networking - NodeBalancers
NodeBalancers are load balancers-as-a-service in the cloud, managed by Linode. They intelligently route incoming requests to backend Linodes to help your application cope with any load increase.
NodeBalancers are available across all regions.
NodeBalancers cost a flat rate of $10/month.
NodeBalancers can terminate SSL traffic on your behalf and expose the requester’s IP through the backend. This is done using configurable rulesets that give you the power to fine-tune admissible traffic.
NodeBalancers can route subsequent requests to the same backend, so all application sessions work correctly.
Traffic is only routed to healthy backends. Passive health checks happen on every request. You can configure active health checks based on your application or service.
Prevent potential abuse – and preserve resources on your backend Linodes – by setting a client connection throttle at the NodeBalancer.
NodeBalancers support balancing traffic to multiple network ports. Several services can be load balanced with a single NodeBalancer.
Limits and Considerations
Maximum number of concurrent connections: Each NodeBalancer support up to 10,000 concurrent connections. If your application needs to support more than that, contact support to determine additional options or consider using multiple NodeBalancers behind a DNS load balancing solution such as Round-Robin DNS.
IP addresses: A public IPv4 address and IPv6 address are configured on each NodeBalancer. Additional addresses are not available.
Private network: Communication with backend Linodes occurs over a data center’s private network. As such, backend Linodes must be located within the same data center as the NodeBalancer.
HTTP support: HTTP/1.1 (HTTP/2 support is not yet available).
Network transfer: Outbound transfer usage is counted towards the account-wide network transfer pool. This pool is the combined total of the network transfer quota of each Linode on the account. Both Incoming transfer and transfer over the private network are provided at no cost.
Connections per second: There are no defined rate limits for the number of connections over a given time period, though certain modes are more performant. A port configured in TCP mode allows for the most number of connections. A port configured in HTTPS mode is the most resource intensive and accommodates fewer connections.
TLS termination: When using a NodeBalancer with an application that requires HTTPS, you can either terminate the TLS connection on the NodeBalancer (HTTPS mode) or on the backend Linodes (TCP mode). When terminating TLS connections directly on the NodeBalancer, there are a few key considerations:
- TLS protocols: TLS v1.2 and v1.3 are supported in HTTPS mode.
- While operating in HTTPS mode, internal traffic sent to the backend Linodes will be unencrypted.
For applications that require a very high connection rate or otherwise need to overcome the above considerations present in HTTPS mode, consider operating in TCP mode and terminating TLS on the backend Linodes.
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