46 Software Networks
eastbound and westbound interfaces are likely to play an increasingly
important role to facilitate the connection of the different subnetworks. It is clear that a very great many new propositions are likely
to emerge in this direction, with extensions of protocols already in
use, such as BGP.
Figure 2.25. A view of SDN networks of tomorrow. For a color version
of the figure, see www.iste.co.uk/pujolle/software.zip
One difficult problem which is beginning to be considered is that
the urbanization of virtual machines which are in the datacenters.
Depending on the optimization criterion, the time of day or the
performance requirements, the virtual machines migrate so that they
are located in the best possible place. Most typically, urbanizations are
done for the purpose of saving energy, which tends to consist of
grouping together the virtual machines on common servers, or for the
purpose of optimizing performance, which involves the opposite
operation – distributing the resources to the servers as much as
possible.
It should be noted that in terms of networks, the optimum
placement of the virtual machines is no longer an equal distribution
between all the physical machines, but on the contrary, the filling of
those physical machines with the maximum possible number of virtual
www.it-ebooks.info
eastbound and westbound interfaces are likely to play an increasingly
important role to facilitate the connection of the different subnetworks. It is clear that a very great many new propositions are likely
to emerge in this direction, with extensions of protocols already in
use, such as BGP.
Figure 2.25. A view of SDN networks of tomorrow. For a color version
of the figure, see www.iste.co.uk/pujolle/software.zip
One difficult problem which is beginning to be considered is that
the urbanization of virtual machines which are in the datacenters.
Depending on the optimization criterion, the time of day or the
performance requirements, the virtual machines migrate so that they
are located in the best possible place. Most typically, urbanizations are
done for the purpose of saving energy, which tends to consist of
grouping together the virtual machines on common servers, or for the
purpose of optimizing performance, which involves the opposite
operation – distributing the resources to the servers as much as
possible.
It should be noted that in terms of networks, the optimum
placement of the virtual machines is no longer an equal distribution
between all the physical machines, but on the contrary, the filling of
those physical machines with the maximum possible number of virtual
www.it-ebooks.info