title: Mnesia can't connect to another node
body: <p>I am setting up a rabbitmq cluster and ran into an issue during the one step in the process. Its straight out of the rabbitmq clustering guide.</p>
  
  <pre><code>root@celery:~# rabbitmqctl status
  Status of node celery@celery ...
  [{pid,20410},
   {running_applications,[{rabbit,"RabbitMQ","2.5.1"},
                          {os_mon,"CPO  CXC 138 46","2.2.4"},
                          {sasl,"SASL  CXC 138 11","2.1.8"},
                          {mnesia,"MNESIA  CXC 138 12","4.4.12"},
                          {stdlib,"ERTS  CXC 138 10","1.16.4"},
                          {kernel,"ERTS  CXC 138 10","2.13.4"}]},
   {os,{unix,linux}},
   {erlang_version,"Erlang R13B03 (erts-5.7.4) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:30] [hipe] [kernel-poll:true]\n"},
   {memory,[{total,25296704},
            {processes,9680280},
            {processes_used,9662720},
            {system,15616424},
            {atom,1099393},
            {atom_used,1082732},
            {binary,89768},
            {code,11606637},
            {ets,726848}]}]
  ...done.
  root@celery:~# rabbitmqctl cluster_status
  Cluster status of node celery@celery ...
  [{nodes,[{disc,[celery@celery]}]},{running_nodes,[celery@celery]}]
  ...done.
  root@celery:~# rabbitmqctl stop_app
  Stopping node celery@celery ...
  ...done.
  root@celery:~# rabbitmqctl reset
  Resetting node celery@celery ...
  ...done.
  root@celery:~# rabbitmqctl cluster worker1@worker1
  Clustering node celery@celery with [worker1@worker1] ...
  Error: {failed_to_cluster_with,[worker1@worker1],
                                 "Mnesia could not connect to some nodes."}
  </code></pre>
  
  <p>What are the possible reasons one node wouldn't be able to connect to another?</p>
  
  <p>Here's the guide I'm following: <a href="http://www.rabbitmq.com/clustering.html" rel="noreferrer">http://www.rabbitmq.com/clustering.html</a></p>