# of IPv4	# of Tor Instances per IPv4	Total # of Tor Instances	Speed per Tor Instance (MiB/s)	Total Speed of All Tor Instances (MiB/s)	Total Port Speed (Gbps)
256	8	2048	40	81920	687
256	4	1024	40	40960	344
256	2	512	40	20480	172
256	1	256	40	10240	86
256	8	2048	20	40960	344
256	4	1024	20	20480	172
256	2	512	20	10240	86
256	1	256	20	5120	43
256	8	2048	10	20480	172
256	4	1024	10	10240	86
256	2	512	10	5120	43
256	1	256	10	2560	21
256	8	2048	5	10240	86
256	4	1024	5	5120	43
256	2	512	5	2560	21
256	1	256	5	1280	11
256	8	2048	2	4096	34
256	4	1024	2	2048	17
256	2	512	2	1024	9
256	1	256	2	512	4
128	8	1024	40	40960	344
128	4	512	40	20480	172
128	2	256	40	10240	86
128	1	128	40	5120	43
128	8	1024	20	20480	172
128	4	512	20	10240	86
128	2	256	20	5120	43
128	1	128	20	2560	21
128	8	1024	10	10240	86
128	4	512	10	5120	43
128	2	256	10	2560	21
128	1	128	10	1280	11
128	8	1024	5	5120	43
128	4	512	5	2560	21
128	2	256	5	1280	11
128	1	128	5	640	5
128	8	1024	2	2048	17
128	4	512	2	1024	9
128	2	256	2	512	4
128	1	128	2	256	2

On Tuesday, February 18th, 2025 at 8:00 AM, usetor.wtf via tor-relays <tor-relays@lists.torproject.org> wrote:

Another question - what's the most optimal count of Tor relays per IP when using an IPv4 /24, i.e. roughly 256 IPs?
Looking for thoughts / guidance as this can quickly be a costly endeavor with slow turn around times on securing data center capacity.

Current hypothesis is around 2 Tor Instances per 256 IPs for 512 relays at 5 MiB/s each needing 21 Gbps port speed. See details below.

Option 1: Is it 8 Tor instances per IP, the current maximum? 2048 total Tor instances across 256 IPs in /24? 1/4 of the current ~8000 running relays (~8200 relays bandwidth measured today)? Seems too many.
Example: At 256 IPs, 8 Tor instances per IP, average speed of 10 MiB/s per Tor relay, need roughly 172 Gbps, which is much less common, especially among volunteer Tor relays.

Option 2: Is it 1 Tor instance per IP, the minimum amount per IP? When Tor is blocked, it's done by IP, so have 8 per IP is less efficient when 256 are available to spread out the relays and minimize blockage, unless the full /24 gets blocked?
Example: At 256 IPs, 1 Tor instances per IP, average speed of 10 MiB/s per Tor relay, need roughly 21 Gbps, which seems much more reasonable using 2 x 10 Gbps links on one node with ~256 cores or split across 2 nodes of each having 10 Gbps and 128 cores.

Option 3: Seems like the ideal would be however many can be utilized per available bandwidth?

Here's a rough sizing table (attached and inline) of Port Speed in Gbps needed depending on # of available IPs, # of Tor instances per IPv4 and Speed per Tor (MiB/s).
Legend: <= 10 Gbps is green, <= 20 Gbps is yellow, and > 20 Gbps is red.

During the Fall of 2021, I saw ~15 MiB/s per Tor Instance and now I see around ~5 MiB/s per Tor Instance (no changes on my servers other than OS and Tor updates).

Current conclusion: I'm looking at the 256, 2, 512, 5, 2560, 21 row as where I'll likely start. 512 is a lot of Tor instances...

~8200 relays bandwidth measured today: https://consensus-health.torproject.org/graphs.html

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On Monday, February 3rd, 2025 at 8:00 AM, usetor.wtf <usetor.wtf@protonmail.com> wrote:

Hi All,

Looking for guidance around running high performance Tor relays on Ubuntu.

Few questions:
1) If a full IPv4 /24 Class C was available to host Tor relays, what are some optimal ways to allocate bandwidth, CPU cores and RAM to maximize utilization of the IPv4 /24 for Tor?

2) If a full 10 Gbps connection was available for Tor relays, how many CPU cores, RAM and IPv4 addresses would be required to saturate the 10 Gbps connection?

3) Same for a 20 Gbps connection, how many CPU cores, RAM and IPv4 addresses are required to saturate?

Thanks!

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