The Making of a Router

Chris Adams cma at
Sat Dec 28 14:53:53 UTC 2013

Once upon a time, Shawn Wilson < at> said:
> I was hoping someone could give technical insight into why this is good or not and not just "buy a box branded as a router because I said so or your business will fail". I'm all for hearing about the business theory of running an ISP (not my background or day job) but didn't think that's what the OP was asking about (and it didn't seem they were taking business suggestions very well anyway).

There's been some technical insight here I would say.  I'm a big Linux,
Open Source, and Free Software advocate, and I'll use Linux-based
systems for routing/firewalling small stuff, but for high speed/PPS, get
a router with a hardware forwarding system (I like Juniper myself).

You can build a decently-fast Linux (or *BSD) system, but you'll need to
spend a good bit of time carefully choosing motherboards, cards, etc. to
maximize packet handling, possibly buying multiple of each to find the
best working combination.  Make sure you buy a full set of spares once
you find a working combination (because in the PC industry, six months
is a lifetime).  Then you have to build your OS install, tweaking the
setup, network stack, etc.

After that, you have to stay on top of updates and such (so plan for
more reboots); while on a hardware-forwarding router you can mostly
partition off the control plane, on a Linux/*BSD system, the base OS is
the forwarding plane.  Also, if something breaks, falls over under an
attack, etc., you're generally going to be on your own to figure it out.
Maybe you can Google the answer (and hope it isn't "that'll be fixed in
kernel 3.<today's version+2>.  Not saying that doesn't happen with
router vendors (quoting RFCs at router engineers is "fun"), but it is
IMHO less often.

The question becomes: what is your time worth?  You could spend hundreds
of hours going from the start to your satisfactory in-service router,
and have a potentially higher upkeep cost.  Can you hire somebody with
all the same Linux/*BSD knowlege as yourself, so you are not on-call for
your home-built router around the clock?

I've used Linux on all my computers for almost 20 years, I develop on
Linux, and contribute to a Linux distribution.  However, when I want to
record TV to watch later, I plug in a TiVo, not build a MythTV box.
There is a significant value in "just plug it in and it works", and if
you don't figure your time investment (both up-front and on-going) into
the cost, you are greatly fooling yourself.

Chris Adams <cma at>

More information about the NANOG mailing list