Many hosts have the ability to attach to multiple networks simultaneously. This can happen over multiple physical network interfaces, a combination of physical and virtual interfaces (VPNs or tunnels), or even indirectly through multiple default routers and/or address prefixes being on the same link. For instance, current laptops and smartphones typically have multiple access network interfaces. A host attached to multiple networks has to make decisions about default router selection, address selection, DNS server selection, choice of interface for packet transmission, and the treatment of configuration information received from the various networks. Some configuration objects are global to the node, some are local to the interface, and some are related to a particular prefix. Various issues arise when contradictory configuration objects that are global to the node are received on different interfaces. At best, decisions about these matters have an efficiency effect. At worst, they have more significant effects such as security impacts, or even lead to communication not being possible at all. A number of operating systems have implemented various techniques to deal with attachments to multiple networks. Some devices employ only one interface at a time and some allow per-host configuration of preferences between the interfaces but still use just one at a time. Other systems allow per-application preferences or implement sophisticated policy managers that can be configured by users or controlled externally. The purpose of the MIF working group is to describe the issues of attaching to multiple networks on hosts and document existing practice. The group shall also analyze the impacts and effectiveness of these existing mechanisms. The WG shall employ and refer to existing IETF work in this area, including, for instance, strong/weak models (RFC 1122), address selection (RFC 3484), ICE and other mechanisms higher layers can use for address selection, DHCP mechanisms, Router Advertisement mechanisms, and DNS recommendations. The focus of the working group should be on documenting the system level effects to host IP stacks and identification of gaps between the existing IETF recommendations and existing practice. After completing some of its initial goals in 2010 the group is also developing three specific extensions: 1) Architecture document, defining consistent approach, recommended practices and requirements for possible protocol changes to improve handling of multiple sets of network configuration objects in networks and nodes. 2) MIF API: While no changes are required for applications to run on multiple interface hosts, a new API could provide additional services to applications running on hosts attached to multiple provisioning domains. For instance, these services could assist advanced applications in having greater control over first-hop, source address and/or DNS selection, interface and other network configuration elements selection. This API will be defined as an abstract interface specification, i.e., specific details about mapping to operating system primitives or programming language will be left out. Network discovery and selection on lower layers as defined by RFC 5113 is out of scope. With the exception of identifying requirements for additional DHCP and/or ND options as well as requirements for possible related changes in these protocols, group shall not assume any software beyond basic IP protocol support on its peers or in network nodes. No work will be done to enable traffic flows to move from one interface to another. The group recognizes existing work on mechanisms that require peer or network support for moving traffic flows such as RFC 5206, RFC 4980 and the use of multiple care-of addresses in Mobile IPv6. This group does not work on or impact such mechanisms. Future work in this area requires rechartering the working group or asking other, specialized working groups (such as DHC or 6MAN) to deal with specific issues.