Nt2580 Unit 6 Lab 1
analytical Essay
1286 words
MANAGEMENT INFORMATION SYSTEMS OMIS 660 FALL 2015 Instructor – Dr. Yipeng Liu
LAB 1 – TCP: TRANSMISSION CONTROL PROTOCOL
Submitted by: Submission Date: 09-25-2015
Divya Malika Vandana
Z1776136
Divya Reddy Chandupatla
Z1768598
SUMMARY
In this lab, we used Transmission Control Protocol (TCP) which is a connection oriented protocol, to demonstrate congestion control algorithms. As the name itself describes, these algorithms are used to avoid network congestion. The algorithms were implemented in three different scenarios i.e. No Drop Scenario, Drop_Fast Scenario and Drop_NoFast Scenario.
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According to the manual, we chose USA from the map list and created a network. • As shown in the picture below, we added Application config, Profile config, ip32_Cloud and two subnets into the project workspace.
• The next step is to set the names of the devices on the network and edit their attributes.
• For the Application config, the name is set to APPLICATIONS. The attributes are edited as shown in the picture below.
Here, the number of rows of Applicaion definition is set to 1 since we are using a single application i.e. FTP. The name of application is given as FTP_Application. In the description of FTP inter request time, the time taken to transfer the file, is set to constant (3600) and the File size is set to constant (10000000) which is 10MB.
• For the Profile config, the name is set to PROFILES and the attributes are edited as shown in the picture below.
Here, the number of rows for profile config is set to 1 and the name is given as FTP_Profile.
• For the west subnet, one ethernet_server and one ethernet4_slip8_gtwy router are connected with a bidirectional 100 BaseT link. The attributes of the server are shown in the picture
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3. DROP FAST SCENARIO
For Drop_Fast scenario, we change the flavour of the TCP Properties to Reno for fast recovery and fast retransmit mechanism. When there is loss of packet, the sender doesn’t wait for the time out and resends the packets immediately using the mechanism of fast recovery and fast retransmit.
Analysing the graph, since there are loss of packets and retransmission, the congestion window size graph fluctuates by increasing and decreasing very frequently.
4. COMPARISION OF THE THREE SCENARIOS
The graph shows comparison of the three scenarios for sent segment sequence number. The green curve represents No_Drop scenario where it shoots up as it is a perfect scenario where there is no loss of packets. Whereas the blue curve which representd Drop_Fast Scenario increases exponentially because there is loss of packets and retransmission takes place.
In this essay, the author
- Describes how the lab used transmission control protocol (tcp) to demonstrate congestion control algorithms, which are used to avoid network congestion.
- Explains the objective of this lab is to set up a network which uses tcp for end-to-end transmission and analyse the size of the congestion window with different scenarios.
- Explains that they started with creating a new project in riverbed modeler. according to the manual, they chose usa from the map list.
- Describes how the lab used transmission control protocol (tcp) to demonstrate congestion control algorithms, which are used to avoid network congestion.
- Explains the objective of this lab is to set up a network which uses tcp for end-to-end transmission and analyse the size of the congestion window with different scenarios.
- Explains that they started with creating a new project in riverbed modeler. according to the manual, they chose usa from the map list.
- Explains how they added application config, profile configuration, ip32_cloud and two subnets into the project workspace.
- Explains that the next step is to set the names of the devices on the network and edit their attributes.
- Explains that for the west subnet, two ethernet_servers and one router are connected with a bidirectional 100 baset link.
- Explains that the flavour is set to tohoe for no_drop and drop_nofast scenarios, and reno for drop
- Explains that the ethernet_wkstn and ethernet4_slip8_gtwy are set similar to the west subnet node.
- Compares the three scenarios for sent segment sequence number. the green curve represents no_drop scenario where there is no loss of packets and the blue curve which represents drop_fast scenario increases exponentially.
- Explains how they gained practical exposure to the riverbed modeler, including the transmission control protocol, additive increase and multiplicative decease mechanisms, and how different algorithms like tahoe and reno effect congestion control mechanisms.
- Explains that the name of the application is set to applications. the attributes are edited as shown in the picture below.
- Explains that for the profile config, the name is set to profiles and the attributes are edited as shown in the picture below.
- Analyzes the results of the no_drop scenario, showing that the congestion window is shot up because there isn't any retransmission of packets.
- Analyzes the congestion window size graph with lots of fluctuations and spikes because discarded packets are retransmitted only after the time out period is reached.
- Explains that for drop_fast scenario, we change the flavour of the tcp properties to reno for fast recovery and fast retransmit mechanism.
- Explains that the segment sequence number is used as a reference number for the segments that are sent from the sender.
- Analyzes the graph that compares segment sequence numbers of the three scenarios. drop_nofast has the slowest growth in sequence numbers.
- Explains the drop_nofast scenario by comparing sent segment sequence number (red curve) with received segment ack number statistic (blue curve).
- Explains how to create a duplicate of the drop_fast scenario by editing the attributes of client_east and assigning 65535 to its receiver buffer attribute.
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