Merge pull request #12025 from mburke5678/BZ-1628615

Document router behavior changes due to rhbz#1584701

Author: mburke5678

architecture/topics/alternate_backends_weights.adoc

@@ -23,9 +23,8 @@ with each endpoint getting at least 1. If the service `weight` is 0 each
 of the service's endpoints will get 0.
 
 The `weight` must be in the range 0-256. The default is 1. When the `weight` is
-0 no requests are passed to the service. If all services have `weight` 0,
-requests are returned with a 503 error.  When a service has no endpoints, the weight
-is effectively 0.
+0, the service does not participate in load-balancing but continues to serve 
+existing persistent connections.
 
 When using `alternateBackends` also use the `roundrobin` load balancing strategy to ensure requests are distributed
 as expected to the services based on `weight`. `roundrobin` can be set for a

dev_guide/deployments/advanced_deployment_strategies.adoc

@@ -156,8 +156,8 @@ service is the `service_weight` divided by the `sum_of_weights`. The
 the sum of the endpoint `weights` is the service `weight`.
 
 The route can have up to four services. The `weight` for the service can be
-between `0` and `256`. When the `weight` is `0`, no new requests go to the
-service, however existing connections remain active. When the service `weight`
+between `0` and `256`. When the `weight` is `0`, the service does not participate in load-balancing 
+but continues to serve existing persistent connections. When the service `weight`
 is not `0`, each endpoint has a minimum `weight` of `1`. Because of this, a
 service with a lot of endpoints can end up with higher `weight` than desired.
 In this case, reduce the number of pods to get the desired load balance
@@ -209,6 +209,9 @@ service with default `weight=1` so all requests go to it. Adding the other servi
 an `alternateBackends` and adjusting the `weights` will bring the A/B setup to life.
 This can be done by the `oc set route-backends` command or by editing the route.
 +
+Setting the `oc set route-backend` to 0 means the service does not participate 
+in load-balancing but continues to serve existing persistent connections.
++
 [NOTE]
 ====
 Changes to the route just change the portion of traffic to the various services.