If you're considering a datagram protocol, you might be interested in some
more modern alternatives to UDP:

UDT: Breaking the Data Transfer Bottleneck
http://udt.sourceforge.net/

Stream Control Transmission Protocol
http://en.wikipedia.org/wiki/Stream_Control_Transmission_Protocol



On Sat, Mar 23, 2013 at 12:17 AM, Jeff Garzik <jgarzik@exmulti.com> wrote:

> Here is a rough draft implementation of a UDP P2P protocol extension
> for bitcoin:
>
>      https://github.com/jgarzik/bitcoin/tree/udp
>      http://yyz.us/bitcoin/udp-v0.patch
>
> Protocol specification (such that it is):
>
> - UDP, bound to same port as TCP P2P (normally 8333)
> - Active, simultaneous TCP P2P connection required (useful against DoS
> and other attacks)
> - Same message format as TCP P2P, same pchMessageStart conventions,
> etc. (my CNetMessage pull req would be helpful here)
> - Multiple P2P messages per UDP packet permitted
> - Max UDP packet size 100*1024 bytes
> - Advertises NODE_UDP in nServices
> - New "getudpcook" TCP P2P command returns a "udpcook" message,
> containing a yummy cookie
> - UDP P2P commands "inv", "tx" and "addr" are handled as if received via
> TCP
> - UDP P2P command "udpsub" sets a mask, that subscribes to one or more
> data broadcasts.
> - When USM_INV_BCAST mask bit is set, receive "inv" messages via UDP
> rather than TCP.
>
> Project and design goals (or, why do this?):
>
> - It is theorized that UDP may be useful for some messages we
> broadcast throughout the network
> - A productive discussion STARTS with code, otherwise discussion
> continues forever.
> - Investigate improving "inv" relay speed
> - Investigate unconditional "tx" broadcasting via UDP, as "inv"
> alternative, for small tx's.
> - Investigate improving block relay speed (or perhaps block header relay
> speed)
> - Open up new design avenues, for P2P patterns more suited to UDP than
> TCP in general.
>
> --
> Jeff Garzik
> exMULTI, Inc.
> jgarzik@exmulti.com
>
>
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