Alcatel-Lucent Alcatel-Lucent NTT Communications Cisco France Telecom Multi-segment pseudowires have been defined to enable emulated layer 1 and layer 2 services to be delivered from an IP based packet switched network over a sparse mesh of PSN tunnels and PW control protocol sessions. MS-PWs can be used to scale PW based networks over both a single AS, or between multiple ASs, and there is a particular need to be able to dynamically route MS-PWs through a given AS to reach PEs at or beyond the edge of the AS, where the route of the PW through each AS needs to be automatically determined. This draft proposes extensions to OSPF to enable the automatic advertisement of summarized PW FECs, thus enabling the dynamic routing of MS-PWs across an OSPF domain.