Mobile Cloud Networking and Mobility Control 121
– the load-sharing algorithm which distributes the data along
multiple paths must ensure that the total bandwidth is at least equal to
that obtained on the best path;
– the use of several paths must enhance the reliability of the
communication;
– the multihoming protocol must support mobility by dealing with
the problems of horizontal and vertical handovers;
– the interfaces of different access technologies should provide
users with better radio coverage.
5.7. Network-level multihoming
In this section, we present three protocols that take care of
multihoming at network level: HIP (Host Identity Protocol), SHIM6
(Level 3 Multihoming Shim Protocol for IPv6) and mCoA (Multiple
Care-of-Addresses).
Before going into detail about HIP and SHIM6, let us introduce the
main principles of these two protocols. In an IP network, the IP
address is used both as the terminal’s identifier and locator. We have
already seen this property in the case of the LISP protocol. This dual
function of the IP address poses problems in a multihoming
environment. Indeed, as each terminal has several IP addresses
associated with its interfaces, a terminal is represented by multiple
IDs. In mobility, when the terminal moves outside of the coverage
range of a given technology, it switches to the interface of another
technology. Communication is then interrupted because the upper
layers think that the different IDs represent different terminals. The
simultaneous transmission of data along several paths is impossible,
because those paths are not considered to belong to the same terminal.
With HIP and SHIM6, we separate the two functions of the IP
address in order to support multihoming. An intermediary layer is
added between the network layer and the transport layer. This layer
enables us to differentiate the node’s ID and its address. The ID no
longer depends on the node’s attachment point. Although the node
may have several addresses, it is introduced by a unique identifier in
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– the load-sharing algorithm which distributes the data along
multiple paths must ensure that the total bandwidth is at least equal to
that obtained on the best path;
– the use of several paths must enhance the reliability of the
communication;
– the multihoming protocol must support mobility by dealing with
the problems of horizontal and vertical handovers;
– the interfaces of different access technologies should provide
users with better radio coverage.
5.7. Network-level multihoming
In this section, we present three protocols that take care of
multihoming at network level: HIP (Host Identity Protocol), SHIM6
(Level 3 Multihoming Shim Protocol for IPv6) and mCoA (Multiple
Care-of-Addresses).
Before going into detail about HIP and SHIM6, let us introduce the
main principles of these two protocols. In an IP network, the IP
address is used both as the terminal’s identifier and locator. We have
already seen this property in the case of the LISP protocol. This dual
function of the IP address poses problems in a multihoming
environment. Indeed, as each terminal has several IP addresses
associated with its interfaces, a terminal is represented by multiple
IDs. In mobility, when the terminal moves outside of the coverage
range of a given technology, it switches to the interface of another
technology. Communication is then interrupted because the upper
layers think that the different IDs represent different terminals. The
simultaneous transmission of data along several paths is impossible,
because those paths are not considered to belong to the same terminal.
With HIP and SHIM6, we separate the two functions of the IP
address in order to support multihoming. An intermediary layer is
added between the network layer and the transport layer. This layer
enables us to differentiate the node’s ID and its address. The ID no
longer depends on the node’s attachment point. Although the node
may have several addresses, it is introduced by a unique identifier in
www.it-ebooks.info