Description
Write a simple interpreter that configures a described virtual network of
switches, routers, and hosts, and then requests that specified operations
be executed on those systems.
The interpreter will take its primary input from a file which is specified
as the only cmd-line arg.
can use python
The language to be interpreted:
prt hello world # only executed by the interpreter – for debugging
# no args means print a blank line
# may appear anywhere in the file (even in config)
use global vars
read all lines of config
create socket pairs
host/router, pretty much the same
VirtualHost VirtualSwitch VirtualRouter
# config info must come first (comments begin with a #) — config info will come first
vs s1 1 # defines the “1” network
# a switch is basically just a cable that fwds ethernet packets)
# switches know macaddrs but not IPaddrs
vs s2 2 # defines the “2” network
vh h1 101 1.1 # name, mac-ip pairs (all macs 100+)
vr r1 102 1.2 103 2.1 # vr -> router AND host (will have IP addrs)
# name, mac-ip pairs (up to 6 pairs total)
vh h3 104 2.2 # name, mac-ip pairs (all macs 100+)
# operations using the nets can only be performed after all config is done
macsend hello_from_h1 101 102 # will be forwarded by vs 1
pause tty # prints “press return to continue”
macsend howdy_from_h2 103 104 # will be forwarded by vs 2
pause 3 # prints nothing
macsend badsend 101 104 # fails – not on same net
pause tty # prints “press return to continue”
macsend bcastmsg_from_h1 101 255 # 255 (all 1’s in a byte) implies bcast
# (handled by switch; goes to from_host also)
# 255 bcast could be used for ARP-like stuff
pause 3
Switches can only be connected to hosts or routers, not to other switches.
Assume there will be a max of 6 switches, and a max of 6 connections to each switch.
Our macsend (link-layer) packet format is:
dest mac 1 byte (macaddr 101 can be stored in 1 byte)
src mac 1 byte (macaddr 101 can be stored in 1 byte)
type 1 byte (0 here for demo macsend – future types may be arp, etc)
length 1 byte (entire packet length)
# assume our length can not exceed 100 + header
# thus, we may need to split packets at IP layer above
payload 0-100 bytes (because our max packet len is 100 + header)
Printing will be tailored to each project.
Switches print nothing during normal operation, but print a message if they
discard a packet bound for a macaddr that is not connected to the switch.
Sending hosts print:
from_hostname: macsend to to_hostname on from_macaddr: payload
Receiving hosts print:
to_hostname: macsend from from_hostname on to_macaddr: payload
Submitting the project for grading:
You should use turnin to submit a tar file containing all of the required
files, including source code, makefile, etc.
The project should compile and link as p2.
To build the project, I will cd to my directory containing your files
and simply type:
rm -rf p2
rm -rf *.o
make
I will run p2 with one or more test files, e.g.:
./p2 test_filename
