[xcp] XCP network emulator

[Marko Zec]

A rudimentary support for XCP router functions has been added to the IMUNES 
network emulator.

The emulator is based on the FreeBSD 4.10 kernel with virtualized network 
stack. Each network stack instance can be mapped to an independent virtual 
node (a router or a host), and by interconnecting such nodes arbitrary 
network topologies can be constructed on a single commodity workstation. More 
details at http://tel.fer.hr/imunes/ 

The XCP functionality was directly borrowed from ISI's experimental 
implementation available from http://www.isi.edu/isi-xcp/ . Basically, only 
the code that operated on dummynet pipes in the original ISI's implementation 
was ported to IMUNES, through integration in ng_pipe bandwidth/delay/queuing 
emulator module (which can be thought of as a kind of dummynet equivalent). 

Before investing more time and efforts into this, I'd like to get a feeling on 
whether such a tool could be usefull in the current protocol development 
stage, so any feedback would be welcome. Moreover, the available ISI code 
seems to be quite a few months old, so I'm wondering if there's a more up to 
date version in the works?

Anyhow, those people willing to try the emulator package for themselves could 
find the necessary instructions at http://tel.fer.hr/dl/ . In case of using 
the pre-build VMware disk image, you'd still have to download and install the 
latest versions of ng_pipe and imunes in order to get the XCP functionality. 
XCP support can be turned on/off through sysctl net.inet.xcp.ng_pipe_enable.

Of course, two or more workstations running ISI's XCP prototype acting as 
end-nodes would also be required, but this part of the story falls outside of 
the scope of this note :-)


Marko