The Effectual Spectrum Defragmentation Algorithm with Holding Time Sensitivity in Elastic Optical Network (EON)

Table 2

Multi-constrained defragmentation algorithm (MCDFA).

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Multi-constrained defragmentation algorithm (MCDFA)

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Step 1: initialize the network status

Step 2: initialize the network parameter N(V, L)

V is the number of nodes, and L is the number of links between the nodes

Step 3: each arrivals R(s,d,D,Gb)

 s-Source, d-Destination, D-Demand, and Gb-Gurd bands

Step 4: find all possible routes(k_i)

 Construct routing table Rt with respective modulation format and number of FSs using Equation (2)

Step 5: for each k_ido

Find the best RSA constraint (N, D) for from Equation (5) for spectrum allocation

 if the exact route is found from Equation (7) then

 Choose the channel from Equation (6) for RSA ← route + spectrum allocation policy

  Allocate R_i to the network

 else

   Reallocate neighboring connections of N,

    Find the best RSA constraint (N, D) for from Equation (5) for spectrum allocation

   if an exact route from Equation (7) is found then

    Choose the channel from Equation (6) for RSA ← route + spectrum allocation policy

    Allocate R_i to the network

  else

   if FSs cannot assign &&  > FI_tthen

  goto step 6:

   else

    Block the connection request R_i

   end if

  end if

Step 6: R_c: set of connections that may be a necessity for reconfiguration

R_l: connection leaving

P_r(x): present route, N_r(x): next route

 if R_cReconfigure Then

  for each link R_c  P_r(x) then

  R_c ← Connection path share with some link R_l (which is occupied high FSs)

   While R_c ≠ Ø do

   R_i occupied the lowest FSs in R_c

    if R_i(shifted upper to lower optical path then

     R_c shares FSs with R_i (which is Occupied High FSs)

    end if

    R_c ← R_c\{R_i(}

   end while

  end for

 else

  for each link R_i  P_r(x) and R_c  P_r(x) then

   if new available FSs ≥ minimum required FSs for (N_r(x)) then

    Reassign route P_r(x) to N_r(x)

   end if

  end for

 end if

Step 7: restart network parameters

Step 8: end loop

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