How to solve redis cluster "Waiting for the cluster to join" issue?

Question

I have 3 machines and create 6 nodes for redis cluster, i have created it successfully months ago, but it dropped now, i try my best to fix it, but it not work, so i clean all data and re-create it from zero,when i use following command to create cluster, it block here, and waiting node join cluster, i do some research for it, i clean my data, log again and again, do it again and again, but it still not work.

redis-trib.rb create --replicas 1 10.2.1.208:6379 10.2.1.208:6380 10.2.1.209:6379 10.2.1.209:6380 10.2.1.15:6379 10.2.1.15:6380

show the result

redis-trib.rb create --replicas 1 10.2.1.208:6379 10.2.1.208:6380 10.2.1.209:6379 10.2.1.209:6380 10.2.1.15:6379 10.2.1.15:6380
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
10.2.1.208:6379
10.2.1.209:6379
10.2.1.15:6379
Adding replica 10.2.1.209:6380 to 10.2.1.208:6379
Adding replica 10.2.1.208:6380 to 10.2.1.209:6379
Adding replica 10.2.1.15:6380 to 10.2.1.15:6379
M: 73b3b99bb17de63aa99eaf592376f0a06feb3d66 10.2.1.208:6379
   slots:0-5460 (5461 slots) master
S: 05b33ed6691797faaf7ccec1541396472b9d2866 10.2.1.208:6380
   replicates f14702ebb1462b313dd7eb4809ec50e30e4eef36
M: f14702ebb1462b313dd7eb4809ec50e30e4eef36 10.2.1.209:6379
   slots:5461-10922 (5462 slots) master
S: 3a9f433a8503281b0ddfc6ec69016908735053b8 10.2.1.209:6380
   replicates 73b3b99bb17de63aa99eaf592376f0a06feb3d66
M: 2fd97e8842828dba6b425b6a30e764fb06915737 10.2.1.15:6379
   slots:10923-16383 (5461 slots) master
S: c46db592d49bc1e9d8b5efb27b9799929c5186a4 10.2.1.15:6380
   replicates 2fd97e8842828dba6b425b6a30e764fb06915737
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join...........................................................................^C/usr/local/bin/redis-trib.rb:652:in `sleep': Interrupt
        from /usr/local/bin/redis-trib.rb:652:in `wait_cluster_join'
        from /usr/local/bin/redis-trib.rb:1305:in `create_cluster_cmd'
        from /usr/local/bin/redis-trib.rb:1695:in `<main>'

Answer 1

From the cluster tutorial on the official Redis website:

Every Redis Cluster node requires two TCP connections open. The normal Redis TCP port used to serve clients, for example 6379, plus the port obtained by adding 10000 to the data port, so 16379 in the example.

This second high port is used for the Cluster bus, that is a node-to-node communication channel using a binary protocol. The Cluster bus is used by nodes for failure detection, configuration update, failover authorization and so forth. Clients should never try to communicate with the cluster bus port, but always with the normal Redis command port, however make sure you open both ports in your firewall, otherwise Redis cluster nodes will be not able to communicate.

The command port and cluster bus port offset is fixed and is always 10000.

I used AWS, but didn't open ports 16379 and 16380, which were the ones causing this issue.