Literally, to behave as if someone, or some group, was your peer.

In telecomunications, peering is an arrangement whereby peers reciripically exchange traffic (IP traffic or POTS traffic) with each other without charging the peers for the traffic, on the assumption that each of the peers benifits from the relationship. Generally the peers are all wholesale suppliers of traffic and this arrangement assumes that the peers are acting as honest brokers for their customers

Peering breaks down when peers are not honest brokers for their customers--widespread peering increases redundancy and reduces the pressure on long-distance links, but there are certain pricing schemes which do not provide incentive for peers to do this.

An apparent instance of this happening can be found here: http://www.nzherald.co.nz/storydisplay.cfm?storyID=3568316&thesection=business&thesubsection=technology