Jim was a member of the Internet Protocol Next Generation (IPng) Directorate within the Internet Engineering Task Force (IETF), which selected IPv6, among several proposals, to become the basis of the IETF's work on an IPng in 1994.

Jim has been a key designer and implementer of IPv6 and contributor to most core IPv6 specifications.

Jim is also a co-author of several Internet specifications and works in progress regarding the interoperation of IPv4 and IPv6 for deployment.

Jim founded the ad-hoc IPv6 Deployment Group working with implementers across the Internet, which became the IPv6 Forum, where Jim is now Chair of the IPv6 Forum Technical Directorate.

Jim is a member of the Internet Society and Institute of Electronics, Electrical Engineers (IEEE).

Jim in July 2001 received from the IPv6 Forum the Internet IPv6 Pioneer Award as the IPv6 Forum's "Lead Plumber".