Message-ID: <55AAACF9.90007@gmail.com>
Date: Sat, 18 Jul 2015 12:46:01 -0700
From: Patrick Strateman <patrick.strateman@gmail.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
	rv:31.0) Gecko/20100101 Icedove/31.7.0
MIME-Version: 1.0
To: bitcoin-dev@lists.linuxfoundation.org
References: <20150718185259.GA3477@muck>
In-Reply-To: <20150718185259.GA3477@muck>
Content-Type: multipart/alternative;
	boundary="------------030202040003040402040300"
Subject: Re: [bitcoin-dev] Do we really need a mempool? (for relay nodes)
Precedence: list

This is a multi-part message in MIME format.
--------------030202040003040402040300
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit

Relay nodes do not need a mempool, but do need some mechanism to avoid
DoS issues.

Wallet nodes can use the mempool for fee estimation (in addition to
looking at past blocks).

On 07/18/2015 11:52 AM, Peter Todd via bitcoin-dev wrote:
> As in, do relay nodes need to keep a record of the transactions they've
> relayed? Strictly speaking, the answer is no: one a tx is relayed modulo
> DoS concerns the entire thing can be discarded by the node. (unconfirmed
> txs spending other unconfirmed txs can be handled by creating packages
> of transactions, evaluated as a whole)
>
> To mitigate DoS concerns, we of course have to have some per-UTXO limit
> on bandwidth relayed, but that task can be accomplished by simply
> maintaining some kind of per-UTXO record of bandwidth used. For instance
> if the weighted fee and fee/KB were recorded, and forced to - say -
> double for each additional tx relayed that spent a given UTXO you would
> have a clear and simple upper limit of lifetime bandwidth. Equally it's
> easy to limit bandwidth moment to moment by asking peers for highest
> fee/KB transactions they advertise first, stopping when our bandwidth
> limit is reached.
>
> You probably could even remove IsStandard() pretty much entirely with
> the right increasingly expensive "replacement" policy, relying on it
> alone to provide anti-DoS. Obviously this would simplify some of the
> debates around mining policy! This could even be re-used for scalable a
> general-purpose messaging network paid by coin ownership if the UTXO set
> is split up, and some kind of expiration over time policy is
> implemented.
>
> Miners of course would still want to have a mempool, but that codebase
> may prove simpler if it doesn't have to work double-duty for relaying as
> well.
>
>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev


--------------030202040003040402040300
Content-Type: text/html; charset=windows-1252
Content-Transfer-Encoding: 7bit

<html>
  <head>
    <meta content="text/html; charset=windows-1252"
      http-equiv="Content-Type">
  </head>
  <body bgcolor="#FFFFFF" text="#000000">
    Relay nodes do not need a mempool, but do need some mechanism to
    avoid DoS issues.<br>
    <br>
    Wallet nodes can use the mempool for fee estimation (in addition to
    looking at past blocks).<br>
    <br>
    <div class="moz-cite-prefix">On 07/18/2015 11:52 AM, Peter Todd via
      bitcoin-dev wrote:<br>
    </div>
    <blockquote cite="mid:20150718185259.GA3477@muck" type="cite">
      <pre wrap="">As in, do relay nodes need to keep a record of the transactions they've
relayed? Strictly speaking, the answer is no: one a tx is relayed modulo
DoS concerns the entire thing can be discarded by the node. (unconfirmed
txs spending other unconfirmed txs can be handled by creating packages
of transactions, evaluated as a whole)

To mitigate DoS concerns, we of course have to have some per-UTXO limit
on bandwidth relayed, but that task can be accomplished by simply
maintaining some kind of per-UTXO record of bandwidth used. For instance
if the weighted fee and fee/KB were recorded, and forced to - say -
double for each additional tx relayed that spent a given UTXO you would
have a clear and simple upper limit of lifetime bandwidth. Equally it's
easy to limit bandwidth moment to moment by asking peers for highest
fee/KB transactions they advertise first, stopping when our bandwidth
limit is reached.

You probably could even remove IsStandard() pretty much entirely with
the right increasingly expensive "replacement" policy, relying on it
alone to provide anti-DoS. Obviously this would simplify some of the
debates around mining policy! This could even be re-used for scalable a
general-purpose messaging network paid by coin ownership if the UTXO set
is split up, and some kind of expiration over time policy is
implemented.

Miners of course would still want to have a mempool, but that codebase
may prove simpler if it doesn't have to work double-duty for relaying as
well.

</pre>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">_______________________________________________
bitcoin-dev mailing list
<a class="moz-txt-link-abbreviated" href="mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfoundation.org</a>
<a class="moz-txt-link-freetext" href="https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev</a>
</pre>
    </blockquote>
    <br>
  </body>
</html>

--------------030202040003040402040300--