PBFT has an "all to all" message pattern, so it means that all nodes need to send to all nodes messages.
While it can sustain up to a third faults, it doesn't mean you'd want to run a deployment of PBFT where you'll have a third of the nodes disconnected....
From: "Ivan Ch" <acizlan@...>
Date: 11/05/2019 05:18 PM
Subject: [EXTERNAL] Re: [Hyperledger Fabric] Major security hole in Hyperledger Fabric - Private Data is not private #fabric #fabric-questions #fabric-dstorage #database #dstorage #dstorage-fabric #fabric-chaincode #ssl
Sent by: fabric@...
If you have trouble opening ports between companies, you shouldn't use a Blockchain at all, since Blockchain is a decentralized peer to peer protocol.
this statement is so flawed, there is no such requirement in ALL public blockchains. at most you can say is this is true for private/consortium blockchains, even that is terribly flawed since even PBFT does, in theory, allow up to 1/3 disconnected peers.
you can never build a consortium while expecting everyone will open firewalls to each other, especially for international projects. it just can't be done, period.