Fast enough to handle an OC-3 on the upstream side?

[Patrick Schaaf]

On Mon, Jul 23, 2001 at 07:28:01AM -0600, Derrik Pates wrote:
> Ok, I have to ask. Does anyone have a similar setup, or can anyone tell
> me, if a dual P2-450 system, with 256 MB of RAM, running Linux 2.4 and
> Squid, with a gigabit fiber card on the interior side and 100 Mbps UTP
> card on the exterior side, will be fast enough to handle NATing our
> network if we get an OC-3 (~45 Mbps)? I want to make sure the box will
> continue to have enough horsepower, as we may soon be jumping to an OC-3
> from a T-1 (The state says this, anyway - we'll see what happens. If we
> upgrade, no one is gonna complain. :), and no one likes complaining users
> or poorly-used connections, right? Right? :)

Without experience in the usage in a typical school network, I have
to ask some questions. Hopefully they will make the situation more
clear to anybody.

A) what is the CPU usage on the box now?
B) how many clients do you have active concurrently, at max.
C) how much growth potential in the number of clients?
D) when using NAT, how many IPs do you present on the outside?
E) how many NATted connections do you now have, concurrently?
F) what is the peak utilization of your T1 line?
G) what is the peak utilization of the internal ethernet interface, now?

How do you learn such numbers? On the NATting/proxying box:

A) continuously watch top, or run 'vmstat 1', during times of high load
B) cat /proc/net/arp | wc -l
C) your guess is as good as anybody else's.
D) you should know that.
E) wc -l /proc/net/ip_conntracko
F) find out, if you don't know.
G) find out as well, if you don't know.

regards
  Patrick