Serge Krier

Serge Krier is a BGP software engineer and Senior Technical Leader at Cisco, where he develops and sustains the BGP stack on IOS-XR platforms. His recent work includes RFC 9234 route-leak prevention (Only-to-Customer), transitive link bandwidth, BGP SRv6 locator tracking, and memory and CPU scale improvements for route reflectors. Serge joined the European Cisco Technical Assistance Center (TAC) before the dot-com bubble. He worked first in the Architecture team, then in the Escalation team, focusing on early IOS-XR products and service-provider customers worldwide. He spent two decades troubleshooting the most complex router and IP/MPLS routing-protocol issues, advising on large-scale network design and delivering technical training. In 2019 he moved to engineering, bringing that field experience to protocol development. He is active in IETF BGP standardization. He co-authored RFC 10005 (BGP Link Bandwidth Extended Community), is the editor of the BGP Unreachable Prefix Announcement d