f(n(t),t)

Power consumption in the subnet

λ max

Total number of ports on a router

C i

Overall energy of the router

a l ( t ) + b

Gain of energy obtained during the deactivation of the ports

f ( k ( i , j , t ) )

The state of ports in sub-networks at time t

q

Quality of service perceived by the user

F ( t )

Set of all requests at the moment t

f s , p ( t ) F ( t )

Observed request of a user at the instant t from a point s to a p.

R ( F ( t ) )

Routing of all requests at time t (see the routing algorithm).

n ( t ) N ( t )

The subnet included in the network at time t

Q ( f ( t ) )

Quality of service set to not exceeded for all requests observed.

D l ( t )

delay when ℓ(t) ports are disabled

Delayn

Normal delay

Maxℓ(t)

Maximum number of ports off on each router