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From Camille Fournier <cami...@apache.org>
Subject Re: Why ZK uses TCP instead of UPD (IP multicast)?
Date Fri, 26 Dec 2014 00:35:06 GMT
The protocol that zk uses, zab, relies on TCP to guarantee ordered delivery
of messages. Without this transport-level guarantee we'd have to do more
work to ensure correctness. It's a nice simplifying element of the
protocol. You can read the original papers or various parts of the
documentation and wiki such as

On Dec 25, 2014 6:51 PM, "Ibrahim" <i.s.el-sanosi@newcastle.ac.uk> wrote:

> Yes you are right when you say "Reliable UDP isn’t a defined standard".
> However, there are some protocols has implemented using UDP. For example,
> some Red Hat apps, protocols, and framework implemented using reliable UDP
> (their own reliable UDP), and they works fast and reliable.
> To answer your question, "what sort of improvements would you expect from
> it, over TCP?"
> Zookeeper uses TCP protocol to send/receive messages. For example, when the
> leader sends proposal to 4 followers, it sends it one by one, meaning that
> it needs to send 4 messages (four outgoing packets). Whereas, to achieve
> same thing using RUDP (IP multicast), here leader only needs to send one
> messages (one outgoing packets), as a result, it reduces the network
> traffic.
> Thank you
> Ibrahim
> --
> View this message in context:
> http://zookeeper-user.578899.n2.nabble.com/Why-ZK-uses-TCP-instead-of-UPD-IP-multicast-tp7580715p7580717.html
> Sent from the zookeeper-user mailing list archive at Nabble.com.

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