As the mobility and the number of affordable, powerful, and highly portable devices becoming networked increases, so will the amount of networked services offered, managed and discovered. In this paper, we discuss the need and use of service discovery mechanisms in future fixed and mobile networks. In particular, we choose to focus on future enterprise networks that we anticipate would need to support both fixed and wireless terminals with IPv6 and mobile IPv6 access. We describe service discovery mechanisms using the Service Location Protocol (SLP) in IPv6, and propose extensions to the protocol for utilisation by visiting mobile devices using mobile IPv6, that will allow service discovery to be performed without breaking compatibility to standard SLP. The extensions introduce 2 new Agents for mobility detection and overcoming limitations of multicast usage by Mobile Nodes in foreign networks. Finally we describe our SLP implementation for IPv6.