The easiest way is have mDNS advertise the SSH service:
sudo cp /usr/share/doc/avahi-daemon/examples/*ssh*.service /etc/avahi/services/
sudo systemctl restart avahi-daemon
On the source host you may need to alter /etc/nsswitch.conf to replace mdns4_minimal with mdns_minimal.
On the source host now say
ssh raspberrypi.local
(or whatever hostname you chose, followed by .local).