Opened 7 years ago

Last modified 8 weeks ago

#7757 assigned enhancement

Maybe revisit node flag weight calculations

Reported by: mikeperry Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: tor-client
Cc: mikeperry Actual Points:
Parent ID: #8453 Points:
Reviewer: Sponsor:

Description

Directory guards (#6526) are going to shift some weight off of middle nodes and on to guard nodes. This potentially changes the weights we should give to guard nodes for the middle hop (see dir-spec.txt Section 3.5.3: https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec.txt#l1858).

However, the bandwidth authorities have consistently measured middle nodes as too slow, and Guard nodes as too fast, relative to the rest of the network on average. Exits come out just about even.

If I had to guess, most likely middle nodes are bogged down because nothing in the flag weight calculations takes into account the load from either dirport usage above, or hidden service usage. Directory usage is possible to estimate, but hidden service traffic sometimes involves Exits (from cannibalized circs), sometimes doesn't (from directly built internal circs), and it's nearly impossible to estimate how much of the network traffic it occupies...

So perhaps #6526 will magically correct this imbalance by shifting directory traffic from middle nodes to Guards. Or, perhaps it will be too much. We should keep an eye on the output of https://gitweb.torproject.org/torflow.git/blob/HEAD:/NetworkScanners/statsplitter.py either way as the directory guards code is deployed.

Child Tickets

Attachments (1)

Node-Flag-Weights.m (5.1 KB) - added by mikeperry 7 years ago.
Mathematica commands to solve the weight equations. Careful: might be pre-#1952.

Download all attachments as: .zip

Change History (6)

comment:1 Changed 7 years ago by mikeperry

It seems like we're not going to need do anything with this, but here's some breadcrumbs in case this falls on somebody else to fix:
https://lists.torproject.org/pipermail/tor-dev/2010-January/001036.html
https://lists.torproject.org/pipermail/tor-dev/2010-September/002521.html

I'll also attach the Mathematica commands I used to verify the solutions.

Changed 7 years ago by mikeperry

Attachment: Node-Flag-Weights.m added

Mathematica commands to solve the weight equations. Careful: might be pre-#1952.

comment:2 Changed 6 years ago by nickm

Keywords: tor-client added

comment:3 Changed 6 years ago by mikeperry

Parent ID: #8453

comment:4 Changed 21 months ago by teor

Severity: Normal

Set all open tickets without a severity to "Normal"

comment:5 Changed 8 weeks ago by gaba

Cc: mikeperry added
Owner: mikeperry deleted
Status: newassigned
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