Quick note on the upgrade process from Expressway Cluster v8.7 and below to v8.8 and above. The database synchronisation/replication ports have changed slightly. 8.7 and previous uses UDP 500 (IKE) and AH 51. DB traffic is encapsulated in this header. As from 8.8 no more encapsulation with AH. TCP ports 4371 – 4372 are used as direct synchronisation/replication. Ensure these ports open on any firewall between the cluster peers.