What is the power law exponent of unstructured p2p networks?

I have found contradictory literature on this topic. Some papers suggest that the power law exponent is close to 2 (between 2.1 to 2.3). But some other papers show this value is higher (around 3). Kindly provide references to any study/references related to this topic.

Here are some links and quotes:

Search in Power-Law Networks

A number of large distributed systems, [...] display a power-law distribution in their node degree. This distribution reflects the existence of a few nodes with very high degree and many with low degree, a feature 开发者_如何学Pythonnot found in standard random graphs

Modeling Peer-to-peer Network Topologies Through “small-world” Models And Power Laws

The real problem here is that large scale p2p networks don't really exist in academia. It's incredibly difficult to scale a real p2p network. There are no great p2p simulators for lookup algorithms which help measure these details.

I've recently started using jxta-sim which is a p2p simulator built on top of planet sim.

jxta sim link - http://jxta.dsg.cs.tcd.ie/

Given that it's an empirical fit, I'd say that it depends on the network (what drives it, how it grows, etc.) and the variation in reported values should be taken as a range (rather than as errors in measurement).