Network Stack Code Re-write (Possible motivations...?)

[Martes G Wigglesworth]

Greetings List.

If I am sending to the wrong list, then please let me know what would
have been a more appropriate choice.

I am attempting to research what is meant when, I saw that Juniper had
re-written the network stack from the base freebsd network stack, to
what is used in JUNOS.  What exactly is meant by this?  What is included
in the network stack, when mentioned that it was completely re-written? 

I am a budding computer scientist, and would like to know where to start
investigating how this would be done, and why they felt that the defacto
network-centric OS for decades needed to be rewritten?

Was this simply so they could rename the portions that they wrote as
their own, in a business-savvy decision making process, or was it
necessary from a technical standpoint?

Any input would be appreciated, and if this question is too broad, then
please point me in the right direction to make further inquiries.

Thanks

Respectfully,
-- 
Martes G Wigglesworth <martes at mgwigglesworth.com>
M.G. Wigglesworth,LLC