Router to MP Health check - How does router behave if MP is not responding?

Hi All,

Want to understand the behavior of router in case the RPC check to Message Processor fails or for some request from client side the router times out because it didn't received any response from MP(this could be due to Target taking more time than what is defined in router timeout or MP is down).

If we have 2 routers and 4 MPs behind these two routers.

RoutersMessage Processors
R1MP1 and MP2
R2MP3 and MP4

Say for some reasons MP1 is not accessible to R1 then R1 will stops sending traffic to MP1 based on RPC checks. Right?

Then later if MP1 is up again then what is the behavior for R1? Will it add MP1 again to the list of MPs registered at R1 automatically or are there any manual steps involved?

Same way for R2, say if both of the MPs are down for some time then what will be the behavior on R2?

What happens if MP3 and MP4 are up again?

Thanks...

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Your understanding is correct. If MP1 goes down for whatsoever reasons, R1 will send all traffic to MP2. Router does health checks for all MP's associated with it and marks a node unhealthy if health check fails. When MP1 comes back, Router will mark it as healthy and distribute the load as per the load balancing algorithm which by default is round robin.

Please go through this document about the router mp behaviour.

http://docs.apigee.com/private-cloud/latest/configuring-router-retry-connections-message-processor

When both MP3 and MP4 goes down, router returns with 502 bad gateway error code. When they come back up, router can send traffic to those MPs. No manual intervention is required.

Router act as a classic http load balancer so you can expect the behavior to be same as what you expect from any other LB like Amazon ELB or Google Load Balancers.

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3 REPLIES 3

Your understanding is correct. If MP1 goes down for whatsoever reasons, R1 will send all traffic to MP2. Router does health checks for all MP's associated with it and marks a node unhealthy if health check fails. When MP1 comes back, Router will mark it as healthy and distribute the load as per the load balancing algorithm which by default is round robin.

Please go through this document about the router mp behaviour.

http://docs.apigee.com/private-cloud/latest/configuring-router-retry-connections-message-processor

When both MP3 and MP4 goes down, router returns with 502 bad gateway error code. When they come back up, router can send traffic to those MPs. No manual intervention is required.

Router act as a classic http load balancer so you can expect the behavior to be same as what you expect from any other LB like Amazon ELB or Google Load Balancers.

Thanks, @rajeshmishra.

Not applicable

@Mohammed Zuber please notice that the Routers are configured already to perform health check. No need to change the configuration.