Enterprise Networking Week 2

Spring 2021, Mondays 5:30-8:00

February 1

Mininet

Lubuntu and Mininet 2.3: finally supporting python3!

Simple example of TCP traffic:

h1---s1---h2
h1---r1---h2

Monitoring pings

Monitoring a TCP connection with netcat

Your "assignment" this second week is to use VirtualBox to build a virtual machine using lubuntu.vdi as its virtual disk:

Download and unzip the lubuntu.vdi file. If you don't have enough disk space, you can use a usb drive or even a usb flash drive of at least 16 GB.
Create a new virtual machine with Type = Linux and Version = Ubuntu (64-bit).
Use the option to use an existing disk, namely lubuntu.vdi. Note this is a two-step process: you must first select lubuntu.vdi as a candidate virtual disk, and then assign it to your new virtual machine.
Under the Display settings, set the graphics controller to VBoxSVGA and the video memory to 64 MB. The VMSVGA video option will not work.
Then start it up! It takes ~20 seconds to start, but after it does, you should see a graphical interface.
It should log you in automatically, but for the record the userid and password are both "mininet". To get a "root" shell, use the command sudo bash, for which you will need to enter the "mininet" password.

The link for lubuntu.vdi (or, more precisely, lubuntu.zip) is on Sakai, in the lubuntu.html file in the resources folder. The lubuntu.zip file is 2.5 GB; the unzipped lubuntu.vdi is somewhere between 7 and 8 GB.

TCP and high bandwidth

Server-side vs client-side TCP

Two high-bandwidth TCP problems:

occasional random packet losses may make it impossible to maintain a sufficient cwnd, as cwnd is approximately 1.225/sqrt(p)
Even without that, it takes a long time for cwnd to rise to the appropriate level, and to rise back after a packet loss

AIMD(𝛼,𝛽): intronetworks.cs.luc.edu/current2/html/dynamicsB.html#aimd-revisited.

intronetworks.cs.luc.edu/current2/html/newtcps.html

Reno with very large queues

Highspeed TCP

TCP Vegas: works really well with 2 above

TCP Westwood: there's a problem here

FAST TCP

TCP Illinois

TCP Cubic