6 Software Networks
Each software network may have its own architecture and its own
characteristics. One software network could be devoted to a VoIP
service, another to IP-TV, a third to a highly-secure application, a
fourth to channeling professional applications, a fifth for
asynchronous applications such as electronic messaging, etc. We
could, in fact, practically create a software network for each user. The
personalized software network is set up at the moment when the user
connects. It is eliminated when the user signs out. However, this
solution does not scale up, and today we are limited to a number of
software networks suited to the hardware capacity of the underlying
physical infrastructure. Each software network receives resources
allocated to it on the basis of the user demands.
It should be noted that, in general, the virtual nodes are found in
datacenters, which may be of varying size and importance: enormous
central datacenters, regional datacenters, local datacenters and small
datacenters such as femto-datacenters. We shall come back later on to
the choices which may be made in this field.
One of the characteristics of software networks is that the virtual
machines can be migrated from one physical machine to another. This
migration may be automated based on whether a node is overloaded or
out of order.
In the physical nodes which support the software networks, we can
add other types of virtual machines such as firewalls, SIP servers for
VoIP, ADSL router, etc. The networks themselves, as stated above,
may obey a variety of different protocol architectures such as
TCP/IPv4, UDP/IPv4, IPv6, MPLS, Ethernet Carrier Grade, TRILL,
LISP, etc.
Isolation is, of course, a crucial property, because it is essential to
prevent a problem on one software network from having repercussions
for the other networks. The handover of streams from one software
network to another must take place via a secure gateway outside of the
data plane. This is absolutely necessary to prevent contamination
between networks, such as a complete shutdown for a network
attacked by a distributed denial of service (DDOS).
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Each software network may have its own architecture and its own
characteristics. One software network could be devoted to a VoIP
service, another to IP-TV, a third to a highly-secure application, a
fourth to channeling professional applications, a fifth for
asynchronous applications such as electronic messaging, etc. We
could, in fact, practically create a software network for each user. The
personalized software network is set up at the moment when the user
connects. It is eliminated when the user signs out. However, this
solution does not scale up, and today we are limited to a number of
software networks suited to the hardware capacity of the underlying
physical infrastructure. Each software network receives resources
allocated to it on the basis of the user demands.
It should be noted that, in general, the virtual nodes are found in
datacenters, which may be of varying size and importance: enormous
central datacenters, regional datacenters, local datacenters and small
datacenters such as femto-datacenters. We shall come back later on to
the choices which may be made in this field.
One of the characteristics of software networks is that the virtual
machines can be migrated from one physical machine to another. This
migration may be automated based on whether a node is overloaded or
out of order.
In the physical nodes which support the software networks, we can
add other types of virtual machines such as firewalls, SIP servers for
VoIP, ADSL router, etc. The networks themselves, as stated above,
may obey a variety of different protocol architectures such as
TCP/IPv4, UDP/IPv4, IPv6, MPLS, Ethernet Carrier Grade, TRILL,
LISP, etc.
Isolation is, of course, a crucial property, because it is essential to
prevent a problem on one software network from having repercussions
for the other networks. The handover of streams from one software
network to another must take place via a secure gateway outside of the
data plane. This is absolutely necessary to prevent contamination
between networks, such as a complete shutdown for a network
attacked by a distributed denial of service (DDOS).
www.it-ebooks.info