This document describes a protocol to reduce handover latency in Mobile IPv6. Mobile IPv6 enables a Mobile Node (MN) to maintain connectivity during handover from one Access Router (AR) to another. However, standard Mobile IPv6 procedures, such as movement detection, new Care of Address (CoA) configuration, and Binding Update, introduce handover latency that is often unacceptable for real-time applications like Voice over IP. This protocol aims to reduce this latency. The protocol allows the MN to send packets as soon as it detects a new subnet link and to deliver packets to the MN as soon as its attachment is detected by the new access router. It defines IP protocol messages necessary for operation regardless of link technology. The protocol enables the MN to quickly detect movement by providing new access point and subnet prefix information when still connected to the current subnet. This allows the MN to formulate a prospective new CoA and send a Fast Binding Update (FBU) message to its Previous Access Router (PAR) to establish a tunnel between the Previous CoA (PCoA) and the New CoA (NCoA). This tunnel allows packets to be tunneled to the new location of the MN. The protocol also provides mechanisms for the MN to announce its attachment to the new subnet link through a Fast Neighbor Advertisement (FNA) message, allowing the new access router (NAR) to confirm the use of NCoA. If the NAR detects that the tentative address is already in use, it discards the inner FBU packet and sends a Router Advertisement with the "Neighbor Advertisement Acknowledgment (NAACK)" option. This helps avoid address conflicts. The protocol also includes messages for network-initiated handover, where the PAR can send an unsolicited Proxy Router Advertisement (PrRtAdv) message containing the link layer address, IP address, and subnet prefixes of the NAR. This allows the MN to configure a new CoA on the new subnet and send an FBU to the PAR prior to switching to the new link. The protocol defines new message formats, including the RtSolPr (Router Solicitation for Proxy Advertisement), PrRtAdv (Proxy Router Advertisement), Handover Initiate (HI), Handover Acknowledge (HAck), Fast Binding Update (FBU), Fast Binding Acknowledgment (FBack), and Fast Neighbor Advertisement (FNA). These messages enable the MN and ARs to exchange information, establish tunnels, and manage handover processes efficiently. The protocol also addresses issues such as packet loss, duplicate address detection (DAD), and erroneous movement. It provides mechanisms to handle these scenarios, ensuring that the MN can maintain connectivity and minimize latency during handover. The protocol is experimental and does not address improving link switching latency. It is intended for use with Mobile IP and allows the MN to engage in Mobile IP operations including Return Routability. The protocol is designed to be flexible and adaptable to different link technologies while ensuring compatibility withThis document describes a protocol to reduce handover latency in Mobile IPv6. Mobile IPv6 enables a Mobile Node (MN) to maintain connectivity during handover from one Access Router (AR) to another. However, standard Mobile IPv6 procedures, such as movement detection, new Care of Address (CoA) configuration, and Binding Update, introduce handover latency that is often unacceptable for real-time applications like Voice over IP. This protocol aims to reduce this latency. The protocol allows the MN to send packets as soon as it detects a new subnet link and to deliver packets to the MN as soon as its attachment is detected by the new access router. It defines IP protocol messages necessary for operation regardless of link technology. The protocol enables the MN to quickly detect movement by providing new access point and subnet prefix information when still connected to the current subnet. This allows the MN to formulate a prospective new CoA and send a Fast Binding Update (FBU) message to its Previous Access Router (PAR) to establish a tunnel between the Previous CoA (PCoA) and the New CoA (NCoA). This tunnel allows packets to be tunneled to the new location of the MN. The protocol also provides mechanisms for the MN to announce its attachment to the new subnet link through a Fast Neighbor Advertisement (FNA) message, allowing the new access router (NAR) to confirm the use of NCoA. If the NAR detects that the tentative address is already in use, it discards the inner FBU packet and sends a Router Advertisement with the "Neighbor Advertisement Acknowledgment (NAACK)" option. This helps avoid address conflicts. The protocol also includes messages for network-initiated handover, where the PAR can send an unsolicited Proxy Router Advertisement (PrRtAdv) message containing the link layer address, IP address, and subnet prefixes of the NAR. This allows the MN to configure a new CoA on the new subnet and send an FBU to the PAR prior to switching to the new link. The protocol defines new message formats, including the RtSolPr (Router Solicitation for Proxy Advertisement), PrRtAdv (Proxy Router Advertisement), Handover Initiate (HI), Handover Acknowledge (HAck), Fast Binding Update (FBU), Fast Binding Acknowledgment (FBack), and Fast Neighbor Advertisement (FNA). These messages enable the MN and ARs to exchange information, establish tunnels, and manage handover processes efficiently. The protocol also addresses issues such as packet loss, duplicate address detection (DAD), and erroneous movement. It provides mechanisms to handle these scenarios, ensuring that the MN can maintain connectivity and minimize latency during handover. The protocol is experimental and does not address improving link switching latency. It is intended for use with Mobile IP and allows the MN to engage in Mobile IP operations including Return Routability. The protocol is designed to be flexible and adaptable to different link technologies while ensuring compatibility with