SignalR Redis backplane connection failure behavior explanation

[jasonycw]

We are using .NET Core 3.1 SignalR with Redis backplane running on AWS.
And sometime, our SignalR hub will throw the following error randomly

Failed to invoke hub method 'SignedIn'.
   StackExchange.Redis.RedisConnectionException: 
      No connection is available to service this operation: PUBLISH Project.Hub.SomeHub:connection:v3sGIq4zJfIHhEwnIUn26A; It was not possible to connect to the redis server(s). 
      To create a disconnected multiplexer, disable AbortOnConnectFail. 
      ConnectTimeout; IOCP: (Busy=0,Free=1000,Min=2,Max=1000), WORKER: (Busy=2,Free=32765,Min=2,Max=32767), Local-CPU: n/a
      ---> StackExchange.Redis.RedisConnectionException: It was not possible to connect to the redis server(s). To create a disconnected multiplexer, disable AbortOnConnectFail. ConnectTimeout

I am not sure why there is these short connection issue between AWS serverS yet, but I saw there is some new update in the 3.1 doc about Custom behavior for connection failures
https://docs.microsoft.com/en-us/aspnet/core/signalr/redis-backplane?view=aspnetcore-3.1#custom-behavior-for-connection-failures

Can there be more explanation on what these codes do and mean, when and why are they needed?

And the example seems doesn't mention where to put "<your_Redis_connection_string>", I suppose it should be

services.AddSignalR()
        .AddMessagePackProtocol() // There is no such method for Microsoft.AspNetCore.SignalR 1.1.0
        .AddStackExchangeRedis(o =>
        {
            o.ConnectionFactory = async writer =>
            {
                var config = new ConfigurationOptions
                {
                    AbortOnConnectFail = false
                };
                config.EndPoints.Add("<your_Redis_connection_string>");

                // Explanation for the following?
                var connection = await ConnectionMultiplexer.ConnectAsync(config, writer);
                connection.ConnectionFailed += (_, e) =>
                {
                    Console.WriteLine("Connection to Redis failed."); // What if I want to use ILogger ?
                };

                if (!connection.IsConnected)
                {
                    Console.WriteLine("Did not connect to Redis."); // What if I want to use ILogger ?
                }

                return connection;
            };
        });

And according to https://gist.github.com/JonCole/36ba6f60c274e89014dd, I think setting AbortOnConnectFail to false is good enough?

public void ConfigureServices(IServiceCollection services) => services
            .AddSignalR(opts =>
            {
                opts.ClientTimeoutInterval = TimeSpan.FromMinutes(1);
                opts.KeepAliveInterval = TimeSpan.FromSeconds(30);
            })
            .AddStackExchangeRedis(Configuration.GetValue<string>("Cache"), opts =>
            {
                opts.Configuration.AbortOnConnectFail = false;
            }).Services

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• ID: c548355c-d88f-b941-0622-56732973123b
• Version Independent ID: bddd7575-422d-4342-af48-f6b0979fb69a
• Content: Redis backplane for ASP.NET Core SignalR scale-out
• Content Source: aspnetcore/signalr/redis-backplane.md
• Product: aspnet-core
• Technology: aspnetcore-signalr
• GitHub Login: @bradygaster
• Microsoft Alias: bradyg