2007 - 2010: co-chair of the IRTF Routing Research Group.
2005 - 2009: member of Internet Architecture Board (IAB)
2005 - 2007: Member of Internet2 Network Research Liaison Council
1999 - 2003: vice chair of ACM SIGCOMM
1995 - 2000: Co-Chair of IEEE Communication Society Internet Technical Committee
1994 - 1996: member of Internet Architecture Board (IAB)
1994 - 2001: Co-chair of the IETF Resource Reservation Protocol Working Group (RSVP)
1993 - 1998: Member of the IETF IPv6 Area Directorate
1992 - 2005: Member of the IETF Transport Area Directorate
1992 - 1998: on the Editorial Board for IEEE/ACM Transactions on Networking
1991 - 1999: Associate Editor for ACM Computer Communication Review