pes Bridging of Ethernet-type of links together is a fairly common procedure and usually works quite easily. The challenges are mostly related to differences in MTU and possible address conflicts occurring at the moment of bridge establishment. However, bridging shared links with point-to-point links, or links with link-layer addresses to links that do not have link-layer addressing, is a much more troublesome task. The difficulties mostly arise from the nodes' assumptions about link characteristics, which cease to be correct after a bridge has been established. For example, a node that only sees a point-to-point link without link-layer addresses and is unaware of that link being bridged to a shared link that has link-layer addresses, may cause problems for other nodes' DAD procedures due to its assumption that DAD is never needed on a link it is attached to. The challenges related to bridging of different types of links continues to be topical in IETF. 3.7 Mobile IP An IPv6 address is anchored to a specific point in the Internet's network topology - the Internet's routing system delivers packets to the location in the network topology indicated by the packets' destination addresses. Generally speaking, as a node moves from the first network point of attachment to the second, the node ceases to be able to receive packets sent to the address that the node had at the first attachment point. Furthermore, if the node attempts to use the address from the first network in the second network, the packets are probably going to be dropped by the second network's ingress filters, and even if not, the return packets will be delivered to the first network, not to the second network where the node actually is. For applications and transport protocols, the change of IPv6 address during a node's movement results in disconnected transport layer sessions. These transport layer sessions, such as UDP and TCP, are always bound to specific IPv6 addresses. The disconnecting transport layer sessions and challenges in receiving incoming