Redis master recognizes slave's IP address by getpeername(2) so that address becomes an address assigned slave's eth0 even if IP aliased (eth0:1) in slave linux box and ```bind <IP address assigned eth0:1)``` in redis.conf.
This is not a promblem in simple master/slave replication except that ```redis-clit -h MASTER info | grep slave``` shows wrong slave's IP address.
Now I introduced Redis Sentinel. Sentinel gets slaves address from result of ```info``` command to master, so sentinel recognizes not slave's eth0:1 but slave's eth0 as slave's IP address.
Sentinel's health check to slave will fail because salve only listen eth0:1. If redis master crashed, sentinel cannot failover because there is no healthy slave.
To fix it, slave calls bind(2) before connect(2) to master if there is ```bind <address>``` in redis.conf and that address is not local address (127.0.0.0/8).