## 3 Problem Description and Proposed Method
a request for which the target host is not known, it will flood the request to every edge port in the network (apart from the input port) in the hope that the host exists in the network and will reply. * **SDN-IP**: It is an ONOS application for routing implementation that allows an SDN to connect to external networks on the internet using the standard BGP. After running those APIs, we can see the routes learned by ONOS, which can be seen using the 'routes' command on the ONOS console. In the legacy ASs, an eBGP router is connected with a single host. The SDN network in our proposed use case consisted of a BGP border router, which acts as iBGP to SDN-IP and eBGP speaker to the external legacy networks. The BGP policies advertised by external network border routers will be received by the ONOS/BGP speakers in the transit SDN and re-advertised to other external legacy networks by SDN-IP as an iBGP peer. SDN-IP translates the best route policies into the ONOS application intent request (AIR) and deploys them into data plane devices as forwarding rules to route the transit traffic into appropriate external domains. Internal BGP speakers were configured to use the TCP port at 179 to communicate with other BGP speakers and the TCP port at 2000 to send the route information to ONOS/SDN-IP instances, and the external BGP speakers were connected to OpenFlow enabled switches. The BGP routers were emulated using the Linux hosts in which the Quagga routing suite was running. The BGP daemon of the Quagga routing suite was used for the BGP routers. Figure 2 shows SDN-IP implementation for an ISP network, where BGP speakers 10.0.1.1, 10.0.2.1, and 10.0.2.101 were connected to OpenFlow switches. BGP speaker 10.0.1.101 was connected to ONOS, that is, SDN-IP. It advertises route information to SDN-IP; using this, the SDN network acts as a transit AS. BGP speakers 10.0.1.1 and 10.0.2.1 were connected to the external AS. These speakers advertise routes to the AS and to other BGP speakers. iBGP speaker 10.0.1.101 listens to these routes and sends them to SDN-IP changes the known BGP routes to intents and ONOS turns the intents to OpenFlow entries. The OpenFlow entries are then deployed into the OpenFlow switches using the OpenFlow protocol. Using D-ITG, UDP flows were generated with varying packet size and packet rate for 15 s. Two log files were generated for both the sender and receiver side. The log file generated at the receiver side contained values for different pe  
Figure 4: System setup simulation environment. as delay, jitter, bit-rate, bytes received, packets dropped and average loss-burst size. On decoding the log file, we received a stream of data containing these performance indicators. The values of these parameters were taken from the log file on receiver's side. Multiple unidirectional flows were sent for fifteen seconds between pairs of hosts in turns by varying transmission rate and packet size to study the performance of the network under low and high load. The packet size set were 512 and 1024 bytes and the packet transmission rates were varied to 100, 1000, and 3000 packets per second. These flows were sent in the traffic via UDP where each host acted both as a client and a server. Ultimately, the log files of flows generated from ten hosts (ref. Figure 2) in the SDN network were further processed to a CSV file using a Python script. The D-ITG data samples generation snapshot is shown in Figure 5.  
Moreover, 507 data samples were captured during the simulation. Figure 6a-d shows the pattern and distribution interval of the data samples for delay, jitter, bit rate and the packet rate, respectively. The bi-variate distribution of numerical attributes can be observed in the pair-plot shown in Figure 7. A pair-plot visualizes given data to understand the best set of features to explain a relationship between two variables (attributes) or to form the most separated clusters. The plot is in matrix format where the \(x\)-axis is represented by row name and the \(y\)-axis is represented by column name.