Date: Wed, 18 Sep 1996 08:57:43 -0500 (CDT) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: nik@blueberry.co.uk (Nik Clayton) Cc: isp@freebsd.org Subject: Re: Routers - hardware received wisdom Message-ID: <199609181357.IAA08874@brasil.moneng.mei.com> In-Reply-To: <199609181019.LAA26906@guava.blueberry.co.uk> from "Nik Clayton" at Sep 18, 96 11:19:05 am
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> Hi,
>
> I'm going to be requiring two network routers, and since FreeBSD is more
> than capable of the task, I figured I'd go for the cheap 486 option.
>
> One of these routers will be sat between a 2Mb/s leased line and a 10Mb/s
> ethernet, and the other will be between 2 10Mb/s ethernets.
>
> As far as I can tell, FreeBSD 2.1.5, a PCI based 66MHz 486DX with 16MB RAM
> and 2 DC201040 PCI network cards should be sufficient.
>
> But can I drop it any lower than that? Would the boxes be fine with 8MB
> RAM? What about 33MHz machines?
>
> Basically, I want to get this done on the lowest spec possible, because if
> I don't, I know that someone will say "Hey, those machines aren't doing
> much, can we run J. Random application on them as well?", and on the whole,
> I don't want that.
>
> I've hunted the mailing lists, and haven't seen anything that's that specific
> on this topic.
My experiences - and I am very familiar with doing things on a budget,
since I run Milwaukee's only free public access UNIX system :-) :
I ran a T1 gateway for a year on a 386DX/40, 8MB RAM, ET50XX and NE2000.
Worked GREAT, did firewalling, and the line was fairly busy. However,
once you got past about 300 pkts/sec (total as reported by netstat),
the box started to get a little sluggish and idle CPU started to drop
below "acceptable" (I want 70% average idle on a router). It could
saturate the T1 with large packet traffic like FTP, etc., no problem
though.
I currently run this same box on a 486DX5/133, PCI, 16MB RAM, ET50XX, and
two DC21041 Ethernets. Still works great, handles 500-600 pkts/sec with
88% idle. The 16MB was convenience not necessity.
One of my main routers is a 386DX/40, 8MB RAM, and six (count: six)
SMC Elite and Ultra Ethernets. It is in the "red zone" most of the time
these days, varying between 40% and 70% idle, and handling an average
of about 300 pkts/sec, and I am looking to replace it with something
faster. The main problem is that I run news.sol.net on one side of it
and all the traffic must go through it... but I refuse to allow hardware
to dictate my network architecture, so I will fix the router :-)
8MB RAM is perfectly sufficient for a pure router. I used to use 4MB,
and only raised it to 8MB because FreeBSD 2.0R would occasionally
freak and lock on 4MB due to some forgotten problem. However, once
you start running userland programs (including things like gated),
your memory requirements may go up.
As for your specific problem: Do not play games with the CPU. If
you are buying new stuff, there is no excuse to buy anything other
than a 486DX5/133. I highly(!!!!!) recommend the AMD 486/133 "ADZ"
variant, it does not even need a heat sink to run cool, and I have
always hated having moving parts on a critical component. The cost
of doing this as opposed to something else is very small.
If you are afraid other people will run things on the box, be a jerk:
partition the system with as little disk space as possible, making it
less tempting to use. Don't provide them with user accounts. And
simply tell them that the machine isn't equipped to handle it, and it
is cheap to build another box for their needs.
Routers should be utility boxes that you jam in a closet in a forgotten
area, and you should be able to forget that they exist. They absolutely
should not be running anything other than the bare essentials needed to
make them route.
I know some people do not share this point of view, but I feel that if
I ever _lose_ a router (happened once, hard drive developed an entire
bad track), I want to be able to be up and running within the hour.
Incidentally: since I keep a custom variant ("cookie cutter router")
of FreeBSD around, when the 386DX/40 with six SMC's I discussed above
did fail, it took me a very short amount of time to have the machine
back on line, reconfigured, and routing.
... JG
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