Is BitTorrent share-ratio enforcement really necessary?

An interesting case study was recently completed which explores the causes and rationale for file-sharing in the P2P community amid proposes a methodology for its improvement. Share-ratio enforcement has long been the topic of debate in the BitTorent community, and this paper makes interesting assertion both for and against it. Yet, I would argue that share-ratios are an outdated means of encouraging sharing as it is a negative reinforcement that ignores the reality of peak swarms and user demands for content.

In "Gifting Technologies: A BitTorrent Case Study," authors Matie Ripeanu, Miranda Mowbray, Nazareno Andrade, and Aliandro Lima examine the BitTorrent file-sharing system and propose changes to the protocol and to the design of BitTorrent torrent tracker sites to promote it.

They use the term "gifting" to refer to a user’s sharing of resources, be it bandwidth, content, or computing power, and the term "freeride" to describe users who consume such resources with contributing anything in return.

The authors point out that "…up to 85% percent of members of the Gnutella file sharing community freeride," and that this portrays the larger problem in some file-sharing communities in that they tend to attract a larger share of so-called freeriders than others.

When Gnutella and other file-sharing communities are compared to that of BitTorrent, the authors make an interesting, though obvious, conclusion that "Since the applications and demographics in these communities are similar, the low level of freeriding suggests the design of the BitTorrent protocol is successful in attracting higher overall user contribution levels."

This is no doubt due to the fact that DL speeds have a direct correlation with UL speeds. They’re directly linked to one another and make sharing, or "gifting," almost mandatory. "Freeriding" is only possible in the sense that if you "hit and run," or fail to upload as much data as you downloaded (share-ratio<1.0)

In a related paper the authors cite called "Gifting technologies," written by Kevin McGee and Jorgan Skageby, various types of "file-gifting" are described.

They write:

Apparent Pseudo–Gifting
During the study there were indications of what could be called apparent ppseudo–gifting. Gifting in this category is similar to pseudo–gifting in that apparent pseudo–gifters also calculate what to gift based on what other downloaders are gifting. But their reactions — if any — to an obvious imbalance were based on less immediate considerations. In some cases, they took account of history — noting that new participants might not yet have much to share, or more seasoned users may temporarily or permanently be unable to share more (crashed disk, virus, etc.) At the more benevolent extreme of this category were apparent pseudo–gifters who measured the exchange in very general terms — almost as an exchange between what they gift and "the general availability of goods in the community at large." As one participant wrote, "Personally I share with everyone, that’s how I’ve made most of my collection, so I think it’s fair to give some back." Thus, there were cases that initially seemed like straightforward pseudo–gifting behavior — cases where leeches were bumped or banned. On closer examination (and interaction), however, analysis sometimes revealed that the pseudo–gifter was actually an apparent pseudo–gifter. After bumping a leech, the apparent pseudo–gifter would continue to allow downloaders who were gifting to the community at large, even if they were not gifting to the individual from whom they were downloading.
Social Gifting
During the study there were only a few cases of fear–based gifting that had to do with reputation and social pressure: "if I don’t gift — there might be reprisals." A number of people in this category gifted in order to maintain the overall social well–being of the community. This should not be confused with social–oriented pseudo–gifting, which was quite common in the community; participants in this category shared "in order to find or make friends."
Ideological Gifting
Although many ideological gifters were interested in challenging what they feel is an "unjust system" of content ownership, distribution, or artist remuneration, there were also many participants who stressed another aspect of the "information wants to be free" theme, namely that "the spirit of sharing" was an important aspect of society, and therefore gifted public domain material as a way to foster this spirit.
Altruistic Gifting
Unlike the study of mp3 newsgroups conducted by Levine (2001), there were a number of indications of altruistic gifting in several different forms. For example, a number of participants were active gifters even though they rarely sought or received any feedback from it. In some cases, these gifters motivated their continuing gifting by saying they felt it was important that exclusive, hard–to–find, or out–of–print items were made more widely available to anyone interested. Another indicator of altruistic gifting came from people who claimed they rarely downloaded anything — in the most extreme cases, these gifters had technical limitations (such as hard drives that were full) that actually prevented them from benefiting by downloading anything themselves. There were even examples of gifters who shared some commonly available items so that other participants might discover and download other, less known items; in other words, they used the popularity of certain gifts as a way to introduce community members to other, potentially interesting gifts.
Fear–Based Gifting
Because the atmosphere of the current file-sharing culture is dominated by legal and economic issues and activities, it was no surprise that many behaviors were motivated by "fear of being caught." Thus, if people felt that gifting some particular item put them at personal risk, they would often stop openly gifting the item. More surprising was the fact that the actions of a number of people were motivated not by fear of personal punishment, but rather by fear that it would make it difficult or impossible for them to continue gifting. For example, there were cases where gifters removed what they called "RIAA–owned stuff" in order to be able to gift other, public domain material more easily.

What’s interesting to note is that I think we all cycle through each of these motivations depending on the the torrent tracker site involved, or what or with whom files are shared.

Certainly an inordinate amount of "fear-based gifting is involved when it comes to maintain ones share-ratio, particularly when it comes to sites like Oink, or Pisexy where an outright ban is threatened if ones share-ratio dips below a certain threshold..

In the case of Oink, where 0.25 is the minimum allowed user share-ratio, the fear of losing access to this private torrent tracker site drives many to dig out old CDs or purchase new ones in desperation, then uploading them as ubiquitous .FLAC files for music "aficionados" to download.

In the case of Pisexy, oftentimes you won’t have enough people leech a file from you to get the ratio back to the magic 1.0, resulting in the uploading of content found elsewhere or an artificially extended sharing of the torrent tracker in your BitTorrent client server.

A problem to note with this was made previously by Bram Cohen, creator of the BitTorrent protocol, who notes:

Just a little bit of threatening to ban people can get the overall balance to be very heavily weighted on the side of uploading, making it difficult for people to accomplish a reasonable amount of upload even if they try.

A recent offering of the documentary "The Corporation" exemplifies the "altruistic" or ideological impetus for "gifting." The director of the movie felt that the message behind the movie, corporate greed and malfeasance, was important enough that the movie should be available to all free of charge. He even went so far as to dedicate a PC in his garage with the sole purpose of seeding the torrent tracker for the film.

In "Gifting Technologies: A BitTorrent Case Study," the authors go on to define the nature of sharing, pointing out that in many file-sharing communities "…most members value the goods obtained during participation higher than their participation costs."

Why is this important? Because file-sharing system designers will need to understand the "…characteristics and consumption patterns of shared system resources as well as gifters’ motivations" if they are to support a higher level of "gifted" contributions.

To expand further on the reasons for gifting, the motivations for such can be defined into 2 categories: extrinsic and intrinsic. The authors note:

Extrinsic motivations are external to the giver, such as financial reward, reciprocated gifts, fame, social capital, the avoidance of punishment, or recognition by friends.
Intrinsic motivations are driven by the giver’s own psychology, ideology and spirituality — such as reinforcement of the giver’s self–valuation as a good and generous person, or promotion of a cause the giver supports. A cause promoted by a gift might be specific to the gift, such as the widespread diffusion of a particular piece of software or a particular musical subgenre, or might be more general, such as the well–being of a particular community or the good of humanity.

The authors make the point that there must always be a healthy balance of the two if file-sharing is to prosper. Too much extrinsic motivation and you cause a "crowding-out" effect whereby intrinsic motivation are diminished by rules and rewards that are considered to be too harsh or controlling.

They write:

The existence of the crowding–out effect is a potential issue for the design of file–sharing systems. Common reasons for file–sharing include intrinsic motivations, and some of the mechanisms suggested to promote sharing introduce an external incentive which is intended to be controlling. It is not clear whether or not such incentives will produce a strong enough extrinsic motivation to make up for any crowded–out intrinsic motivation. Therefore, the effect of such incentives needs to be monitored by sharing communities that adopt them, to check the incentives are not counterproductive.

Likewise, if there is too great a reliance on intrinsic motivation alone then you create a "crowding-in" effect which is where people share very little bandwidth, content, etc., as there is a perceived lack of repercussion for doing so.

What distinguishes BitTorrent best from other file-sharing communities is that it has "optimistic unchocking," an incentive mechanism to encourage sharing and cooperation. Each peer periodically uploads data to another peer with which it has not shared anything recently, allowing new peers an opportunity to participate in the swarm and share data. Thus, the greater the upload speeds a user selects the greater the number of peers one will be connected to and be able to share with.

In the table compiled below, the authors dissect bt.etree.org, easytree.org, and alluvion.org to discern the nature of file-sharing in the BitTorrent community and also to gauge the design of the BitTorrent protocol and its ability to increase cooperative behavior as compared to other P2P programs.

What the table concludes is startling, as it notes that at most a mere 6% of users upload nothing at all as compared to a whopping average of almost 85% of the P2P population of Gnutella, eDonkey, and other P2P communities.

As an added note to the chart it must be pointed out that peers that have not uploaded data are not necessarily "…trying to freeride," as the authors point out.

…they may be willing to upload but are simply unable to at present. Indeed, some peers that had uploaded nothing at the time of our first etree sample, uploaded data later.

This is often the case for files that have already passed the "peak" of the swarm which results in a diminished demand for data to be uploaded to others relative to the available amount of data available for download. Again Oink and Pisexy are perfect examples of this in that many files will have a large amount of seeders yet a relatively low number of leechers. This translates into very fast download speeds but rather long waits in terms of seeding the file to achieve a 100% share-ratio.

As Bram Cohen, creator of the BitTorrent protocol previously pointed out:

What typically happens in a single torrent is that at the beginning upload and download ratios are reasonably correlated, then over time people finish downloading, and some of them leave, but a significant number of seeds remain.
After a while there’s a period of time where there are many more seeders than downloaders. Anyone who joins the torrent at this late time will be generally get a download rate limited by their download capacity, and anyone who tries to upload to them will only be able to do so at a low rate.
Such people will have very out of whack upload/download ratios, but they’re downloading from otherwise unutilized upload resources, and hence not being anywhere near the drain on the system that their total upload/download ratio indicates.

Based on the nature of peak swarms, it begs the question: Is share-ratio enforcement really necessary? Cohen also pointed out that "…the tit-for-tat nature of the BitTorrent protocol is sufficient enough to stop destructive leeching…(and) is robust enough to handle file sharers who limit their upload and do not seed after the file has finished downloading."

I’d argue that no, share-ratio enforcement is not the end all solution that it has come to be.

Taking another look at the nature of peer distribution and data sharing, the authors have created an excellent graph that display the nature and distribution of peers on 3 different torrent tracker sites. As shown below, Easytree has a larger degree of sharing which they attribute to the ADMINs enforcement of share-ratios.

The results are pretty much neck and neck with even Alluvion only having 10% less peers with a perfect 1.0 sharing ratio as compared to Easytree.

share-ratios do certainly assist in enticing people to upload and share data with others but, it can also be said that sharing will be done irregardless in order to be able to download data from others per the very nature of the BitTorrent protocol itself. Thus, it can be said that file-sharing in the BitTorrent community is an inherent characteristic that defines and separates it from the rest of the pack.

The authors make the distinction that 2 factors, a "psychological effect," and the "economics of effort," can be attributed to the reason why sharing is arguably inherent in the BitTorrent community.They write:

Firstly, the general user perception is that BitTorrent economic incentives to penalize freeriders are always working, thus the psychological barrier to attempt to freeride is high. Secondly, most popular BitTorrent clients cannot be configured for freeriding and it takes considerable effort and skill to modify the source code of a client to change it to a freerider.

This again brings up the discussion of the need for the reform of share-ratios on torrent tracker sites, or at the very least a recalibration of what the incentives are to be for the both the uploading and downloading of data.

Cohen notes:

(Leechers are) engaging in perfectly reasonable and non-destructive behavior and the site is trying to punish him for it, thus fostering the creation of clients which lie about their statistics. This is the site’s fault, and the result could do serious damage to the value of BitTorrent statistics generally. Sites which do this are being extremely destructive, and the way they grandstand about how they’re fostering sharing really ticks me off.
Even if almost everyone quit the instant their download was completed you’d still have decent download rates, they’d just be closer to everyone’s upload rates.

This is the biggest caveat against unfettered enforcement of arbitrary share-ratios, especially when it cannot be said for certain that a user with a share a ratio of a mere 0.25 or so in any way affects the overall experience of those users with higher ratios than he. If anything, he helps their ratios out in the first place as they are much more likely to get the file as whole earlier and therefore upload more of it to other users especially those with lower share-ratios. Sometimes without a concerted effort and persistence some users are forced to languish with low share-ratios. The answer would be to either limit what they download or seed their downloads for a longer period of time but, in either case it goes against the very basic premise of file-sharing and ignores the the users intent. He may want to seed and share a file yet, if nobody wants to download it what is he to do?

The next table, as shown below, shows the seeding ratios of 6 different torrent tracker sites.

The authors attribute the variance of the results to 4 different factors;

1. Communities with undeniably legal content see higher seeding ratios

Among the sites that do not use extra mechanisms to increase cooperation (etree, piratebay, alluvion, and torrentportal), the sites that enable distribution of only legal content (etree and alluvion) have larger seeding ratios.

2. Broadcatching increases the seeding ratio

Btefnet torrents have significantly more seeding than those in piratebay and torrentportal. The use of broadcatching may explain this.

3. Sharing ratio enforcement increases seeding ratios

Easytree torrents have significantly more seeding than those at any other sites. We attribute this to the sharing ratio enforcement: this is an extrinsic incentive which does not appear to crowd out other motivations.

4. The social characteristics of different communities strongly influence sharing behavior

The moderator of easytree attributes the relatively high amount of cooperation to the sharing culture among offline consumers of the type of content (bootleg recordings) distributed via easytree. When a large group of new users who did not share this culture joined easytree the sharing ratio went down, and site administrators successfully introduced sharing–ratio enforcement to reverse its decline.

I do have to say that The Pirate Bay’s seeding ratios are always horrible in my opinion but, it has little to do with legal or illegal content. It has to do with the site being a public one, where anyone and anybody can log on, join a swarm, and take a peek at your IP address if you’re not careful. Thus, many may simply get the files they want and then quickly leave. Why would they want to stick around and seed, as they only risk getting caught or harassed? This alludes to the safety and the comfort of private torrent tracker sites but, again they are oftentimes subject to share-ratios unlike The Pirate Bay.

If The Pirate Bay is as robust and as healthy as many would agree it to be, their user traffic being an important statistic, then wouldn’t it stand to reason that if it were to merely go private that then it would reduce people’s fears of seeding? Can it not be hypothesized that a private site with no share-ratio enforcement could be just as healthy as one that has none?

Another startling revelation is that the top 10% of uploaders, in more than half the torrents studied, contribute "… more than 79 percent of all the bandwidth used in the torrent. This is no doubt due to the difference in user connection speeds as opposed to the throttling of the maximum upload speeds for the client server they are using. Users who are part of the swarm early on will tend to be able to upload a significantly larger amount of data than other users who enter the swarm later.

This again makes the argument that share-ratios are a moot point in some cases as users are in fact penalized oftentimes by merely joining a swarm later than others, which has the effect of inhibiting the amount of data they can effectively upload as the number of peers looking for data is lower than it was previously to their arrival.

In conclusion of the author’s study they make the following recommendations for "gifting," or sharing, technology improvement at the torrent tracker site and BitTorrent protocol levels:

Promote both gifting and trading

In BitTorrent communities, gifting and trading coexist. At the BitTorrent sites in our study other than easytree, there is no incentive to seed. Nevertheless seeding, a good example of gifting, occurs in these sites, together with trading in the form of uploading of content in order to download. Easytree’s extrinsic incentives do not appear to crowd out other motivations, and both types of motivation can be present for a single peer.

Designers of gifting technologies should therefore not assume that users are exclusively interested in gifting or in trading, and should aim, while monitoring for possible motivation crowding, to concurrently encourage both types of contribution.

Support cultural norms for gifting.

According to easytree moderators, the presence (or absence) of a cultural norm for ‘sharing’ has a noticeable effect on the levels of altruistic contributions.

More generally, designers of gifting technologies should consider adding features to support social and cultural norms that promote gifting. For instance, there are notices on BitTorrent sites and clients which try to create a social norm by exhorting users to keep their clients running after they have finished downloading. It is plausible that these have a positive effect on the amount of seeding.

Take prolific gifters into account

Our measurements of etree revealed that even in the presence of an incentive mechanism, a small fraction of all peers is responsible for the majority of resources provided. Among gifters, this concentration was even more pronounced. This observation should be considered by designers. It is important not to assume that all peers will be able to contribute equally, and the efficient use of the resources owned by the small fraction of gifters who contribute most is likely to be a key issue in the efficiency of the system. Similarly, encouraging these gifters to keep participating in the system is important to assure a sustained level of contributions. Of course, any incentive provided to such users should be carefully designed so as not to crowd out intrinsic motivations for gifting.

Our study of BitTorrent communities supports the idea of “economics of effort” applied to gifting: that the easier it is for users to gift, the more likely they are to do so. The rest of our suggestions arise from this idea.

Make gifting the default

Economics has frequent examples of the power of the default choice. For instance, the Economist reported that when an American firm changed their employee pension plan from opt–in to opt–out the level of enrolment jumped from 49 percent to 86 percent (Economist, 2005). Similarly, in communities based on gifting, one way to reduce the effort needed to gift is to make gifting the default, so that it takes some effort not to gift. For BitTorrent clients, uploading while downloading is the default; changing this behavior requires changes to the client source code. We believe that this is an important factor in keeping freeriding in BitTorrent to a low level.

Increase the effectiveness of gifting

Some of the suggestions for improving the BitTorrent protocol in this section are concerned with reducing protocol BitTorrent overheads, and, as a result, increasing the amount of useful gifting that takes place for a fixed amount of contributed resources. Since community members are generally more likely to gift if they perceive that their gifts are efficiently used and have a strong positive effect on the recipient, increasing effectiveness may also increase peers’ motivation to gift.

Make gifting safe

Our data shows that users can be reluctant to seed files with illegal content. The burden of legal, ethical, or security–related risks as a consequence of gifting can be seen as a particular type of effort required for gifting.

Make gifting a byproduct of actions carried out by users for their own benefit

Users’ contribution to the Napster index occurred as a natural byproduct of their actions carried out for their own benefit, e.g., when downloading songs to a portable music player or burning a CD (Bricklin, 2001). Thus, in Napster, gifting occurred with no effort from the gifter at all. Similarly, the seeding that occurs in the time between a btefnet client finishes downloading new content and the user noticing that the content has been downloaded is another example of gifting as a byproduct.

Allow different kinds of gifting with different effort levels

Effortless gifting, or gifting by default, is not always possible. However, designers of gifting technologies generally have the option of enabling different types of gifting, some of which require limited effort, so that users can choose their gifting levels. This can be seen in BitTorrent: most peers participate in chunk trading, a smaller proportion of them are seeders, and an even smaller number provide original content.

Another example of a gifting technology with differing effort levels is online newsgroups: Bradley Horowitz of Yahoo! speculates that only about one percent of Yahoo! user population might create a new group while ten percent might add content to an existing group (Horowitz, 2006). Naturally the rewards and incentives that motivate contributions should be commensurate with the effort involved.

Easytree’s sharing ratio enforcement mechanism has, in some cases, the side effect of creating a motivation to upload original content, a type of contribution that requires more effort than simply uploading existing content. A member whose sharing ratio is below the low sharing threshold cannot join new torrents. In this situation, one way for the member to raise its sharing ratio is to contribute new content. In this case there is a substantial reward for the extra effort: regaining the ability to join new torrents

I tend to agree with all the points they make as they highlight that share-ratio enforcement shouldn’t be the sole focus of torrent tracker site ADMINs efforts to increase content and data sharing among peers. Negative reinforcement as ones sole focus can never be a good thing and makes the need for seeking out alternative methods that much more important. At the very least, the suggestion that Cohen made should be heeded, that "… user ratios should not be monitored at the peak of each swarm, or if a torrent is heavily seeded."

Moreover, I think Cohen sums it up best when speaking about the overall health of the BitTorrent community, in that "…the tit-for-tat nature of the BitTorrent protocol is sufficient enough to stop destructive leeching…(and) is robust enough to handle file sharers who limit their upload and do not seed after the file has finished downloading." I daresay that share-ratios are in many ways entirely unnecessary for private torrent tracker sites as files that are in high demand will automatically result in excellent download speeds for all.

A private Pirate Bay anyone?

Looking for more stuff to download or watch?
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uTorrent – A Beginner’s guide to BitTorrent downloading

 

PUBLIC vs PRIVATE – BitTorrent download sites explored

 

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