# Design of Optical Tunnel Switching Networks for Big Data Applications
## 5 Network Performance and Its Applications
### Traffic Management  
Figure 17 shows the traffic distribution of a two-plane optical tunnel switching network with 25 nodes. The maximum available bandwidth between any two nodes is two wavelengths, and the average available bandwidth is 2/3 wavelengths. Generally, the traffic distribution is uneven, so we can combine it with SDN scheduling to meet our bandwidth requirements.  
**Method 1:** We can use three nodes to share the bandwidth of the direct tunnel through SDN scheduling. For example, from node N (1, 5) to node N (5, 5) is 2\(\lambda\) bandwidth, node N (5, 5) uses 4/3 \(\lambda\) bandwidth as well as node N (5, 4), and node N (5, 3) use 1/3 \(\lambda\) bandwidth. This condition can be set on the SDN switch of node N (5, 5).  
**Method 2:** We use the wavelengths assigned by neighboring nodes, assuming that the original node goes from node N (1, 5) to node N (2, 5), node N (3, 5), node N (4, 5), and node N (5, 5) uses two wavelengths for communication between nodes. Except for node N (5, 5), which uses 4/3 \(\lambda\) bandwidth, other nodes such as node N (5, 4) and node N (5, 3) use less than 2/3 \(\lambda\) bandwidth, as shown in Figure 18. The details of the change in traffic volume are shown in Figure 19 and described in detail below.  
Due to traffic changes, the bandwidth requirement of node N (5, 5) exceeds the 4/3 \(\lambda\) bandwidth. If the sum of the bandwidth of node N (4, 5), node N (4, 2) and node N (4, 1) is equal to or less than the 1\(\lambda\) bandwidth, we can allocate a \(\lambda_{3}\) of node N (4, 5) and change it to node N (5, 5), so that a wavelength of 3\(\lambda\) can be used from node N (1, 5) to node N (5, 5), including node N (5, 4) and node N (5, 3), which is shown in Figure 19. However, the total bandwidth used by node N (5, 5) for the entire network is still  
Figure 16: Throughput of optical tunnel switching network with 49 nodes.  
Figure 17: Traffic distribution for Method 1 of two-plane optical tunnel switching network with 25 nodes.  
limited to 16\(\lambda\). Therefore, if the bandwidth requirement of a node exceeds the 2\(\lambda\) (200%) bandwidth (red light), including relay tunnel nodes, then we can allocate the neighbor nodes that are smaller than a \(\lambda\) (100%) bandwidth (green light), including relay tunnel nodes to this busy node (red light) to avoid traffic loss.  
The traffic management of a three-plane optical tunnel switching network with 49 nodes is similar to the traffic management of a two-plane optical tunnel switching network with 25 nodes.  
When the traffic distribution is uneven, in order to handle all operations of traffic changes, the algorithm of real time traffic monitor and management is designed as follows:  
```
2: Scanning traffic for all nodes
3:{
4. If the node's traffic exceeds 200%, then
5:{
6. Analyze the traffic of the nodes, and then find the busy tunnel.
7. If there is a neighboring node whose traffic is less than one \(\lambda\) bandwidth, then
8. {
9. Assign a \(\lambda\) bandwidth of the neighboring node to the busy node.
10. }
11: }
12: }
```  
**Algorithm:** Real Time Traffic Monitor and Management