Well the answer seems to be (nearly) unanimous. Although large
computational loads should not impact on the routing performance of
our gateway machine, having to forward all those packets will
definitely impact our computational performance. Since the Sparc-1
seems plenty fast enough to forward packets, it is a waste of
computational resources to use the Sparc-2 as a gateway. One poster
suggested that even a 286 PC with two ethernet cards would be
sufficient for our purposes, thus freeing up all of our computational
resources (see below).
Muchas to:
brendan@cs.widener.edu
stefan@centaur.astro.utoronto.ca
morrow@cns.ucalgary.ca
mike@inti.lbl.gov
thakur@zerkalo.harvard.edu
kalli!kevin@fourx.Aus.Sun.COM
uunet!cos.com!hurless@UCSD.EDU
JET@UH.EDU
wallen@cogsci.UCSD.EDU
peter@Civil.Concordia.CA
agw@math.canterbury.ac.nz
A selected summary follows the originally posted question.
------My Original Post--------
We have just subnetted our network of 10 workstations. Right now we
are using a sparc-2 as our gateway. We only have two sparc-2's and we
use them for big number-crunching jobs. We are concerned that big jobs
on our gateway might impact it's performance or, conversely, that
using it as a gateway will slow down the user's jobs. It has been
suggested that we take one of our older sparc-1's and use it as the
gateway, but it's not clear that this is the right way to go either.
So our questions are:
1) Which is a better gateway, a loaded sparc-2 or a lightly loaded
sparc-1? When is say "loaded", I mean running X (mit or openlook), and
perhaps 1-5 background jobs of various sizes (I've seen them go up to
30 meg of memory). When I say "lightly loaded", I mean running X.
2) How much of our computational power are we compromising by using
the Sparc-2 as a gateway? Will all that traffic slow down our
background jobs?
We can put 16 or 32 meg of memory on the sparc-2, and
the sparc-1 has 8 meg right now, but we can probably
upgrade that if necessary.
---------Selected Summary---------
From: Stefan Mochnacki <stefan@centaur.astro.utoronto.ca>
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 91 14:32:46 EST
Are you using any fancy tools like SNMP to manage the gateway? Is
the traffic through the gateway super-heavy? If not, I would strongly
recommend that you get a stripped-down AT clone and two WD8003E ethernet
cards, and install the PC-ROUTE software from accuvax.nwu.edu =
129.105.49.1. This should cost under $1000, and give you trouble-free
operation.
You can put more than 2 cards in it (i.e. more than 1 sub-net). You can
also use a serial port for SLIP. A fast ( > 12 MHz) AT clone will give
excellent performance; an 8 MHz XT "turbo" will be perfectly adequate
for most uses. PCROUTE comes with quite a lot of documentation.
I installed such a set-up to link our Mathematics Department, and it has
worked well (just an 8088 XT @ 8 MHz).
Stefan Mochnacki
David Dunlap Observatory
Dept. of Astronomy
University of Toronto
From: morrow@cns.ucalgary.ca (Bill Morrow)
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 91 12:43:47 MST
We use a Sparcstation 1 as a gateway for a network of about 20 machines.
It also is used for code development and some file serving to both
sides of the gate. It runs Sun's Openwindows.
I don't notice any objectional loading from the gateway function.
The only performance degradation occurs when someone outside does massive
file I/O, which is not a problem with the gateway, but the file-serving.
I would say an SS2 is overkill. Use the SS1.
__________________________________________________________
Bill Morrow voice: (403) 220-6275
Clinical Neurosciences fax: (403) 283-4740
University of Calgary Internet: morrow@cns.ucalgary.ca
From: "Manavendra K. Thakur" <thakur@zerkalo.harvard.edu>
To: bill@kepler.ucsd.edu (Bill Reynolds)
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 04 Dec 91 16:00:04 EST
>>>>> On Wed, 4 Dec 1991 18:04:29 GMT, bill@kepler.ucsd.edu (Bill Reynolds) said:
> 1) Which is a better gateway, a loaded sparc-2 or a lightly loaded
> sparc-1? When is say "loaded", I mean running X (mit or openlook),
> and perhaps 1-5 background jobs of various sizes (I've seen them go
> up to 30 meg of memory). When I say "lightly loaded", I mean running
> X.
I would recommend that you dedicate a SS1 as your gateway. Don't run
anything on it other than packet-forwarding. This will give you
pretty good routing capabilities at a reasonably cheap cost. An IPC
or LPC from Sun costs around $5k these days (with edu discount). So
if you dedicate a SS1 to routing, you might want to look into buying
an additional IPC so that your users still have the same number of
machines to use as before.
Essentially, this operation means that you will be buying yourself a
really cheap router for $5k.
Of course, cisco makes some really cheap routers too, so if you have
aroudn 5-6k to spend, you might just want to buy one of those instead.
Buying a cheap cisco router would give you the advantage of being able
to easily upgrade the router to a higher performance model in the
future should you ever require more bandwidth, etc.
> 2) How much of our computational power are we compromising by using
> the Sparc-2 as a gateway? Will all that traffic slow down our
> background jobs?
Believe it or not, a host-based CPU can easily spend 30-50% of its
time doing nothing but processing network traffic! I kid you not.
There's a significant amount of protocol overhead. This is why using
a host-based machine as a router is such a BAD idea.
Experimental implementations of TCP/IP (cf. Van Jacobson's work) do
exist that reduce the amount of per-packet handling down to about 100
machine instructions. But these are a long way away from being
available in your Sun.
So if you're doing CPU-intensive work on your sparcstations, you
really don't want that machine to route packets as well.
But the proof of the pudding in the testing. Why don't time a big
job, then turn off routing, and rerun the big job. See how much
difference it makes. Without doing that kind of experiment, you'll
never really be sure.
> We can put 16 or 32 meg of memory on the sparc-2, and the sparc-1
> has 8 meg right now, but we can probably upgrade that if necessary.
You're running X windows on a sparc-1 with only 8 MB of memory? Good
heavens, that will make it unnecessarily slow -- not much faster than
a 3/60!. Regardless of whether you turn on routing or not, you should
make it a high priority in your budgeting to add more memory to your
sparc-1 machines.
Good luck!
Manavendra K. Thakur Internet: thakur@zerkalo.harvard.edu
Systems Programmer, High Energy Division BITNET: thakur@cfa.BITNET
Harvard-Smithsonian Center for DECNET: CFA::thakur
Astrophysics UUCP: ...!uunet!mit-eddie!thakur
From: uunet!cos.com!hurless@UCSD.EDU (Brian Hurless)
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 91 17:23:11 EST
Judging from the tone of your letter, performance seems to be very
important at your site. Using a workstation as a gateway isn't the best way
to do it from a performance standpoint. A lot of network activity can really
bog down the workstation. Conversely, if the gateway is loaded down with a
lot of heavy duty jobs, it can be a bottleneck for the network and degrade the
performance of all the machines.
We have a network of Sun3s that is broken into a number of subnets
using Suns as gateways. Our network is lightly loaded so this works fine for
us. But we do experience slow response times every now and then. I know that
Sun4s are faster, but by the time you've burdened them with X and several
other macho apps, the speed increase has probably been canceled out.
I suggest you buy a router instead. I understand that they are
becoming very affordable these days.
--
Brian Hurless hurless@cos.com ///
Network Systems Administrator hurless%cos.com@uunet.uu.net ///
Corporation for Open Systems {uunet, sundc, hadron}!cos!hurless \\\///
-------------------------------------------------------------------------\XX/----
From: J Eric Townsend <JET@UH.EDU>
To: bill@kepler.ucsd.edu (Bill Reynolds)
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 91 18:27:11 CST
Bill Reynolds wrote:
>1) Which is a better gateway, a loaded sparc-2 or a lightly loaded
>sparc-1? When is say "loaded", I mean running X (mit or openlook), and
A sparc-1 is a reasonably fast gateway, but we use a sparc-2 because
that's what we upgraded to. :-)
Beware slow ethernet cards! spend the most you can afford on the card.
Also, (this is from a sun tech) each byte going in/out of the ethernet
card generates an interrupt for the kernel because the lance ethernet
chip doesn't have a cache. Sun has a new sbus ethernet card out with a 64KB
cache + scsi controller. I dunno how much it costs.
--
J. Eric Townsend - jet@uh.edu - Systems Wrangler, UH Dept of Mathematics
vox: (713) 749-2126 '91 CB750, DoD# 0378
From: peter@Civil.Concordia.CA
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Thu, 5 Dec 91 11:09:46 PST
Bill,
In my experience, a Sparc 1 does an excellent job as a gateway.
Having the Sparc 2 routing will only only slow down your users'
jobs, if they're heavy compute instensive tasks, the Sparc 2 will
probably already be slow enough as it is.
===============================================================
Peter Kaldis | Civil Engineering
Unix Lizard | Concordia University
(514)-848-7819 | Montreal, QC
peter@Civil.Concordia.CA | CANADA
===============================================================
From: Brendan Kehoe <brendan@cs.widener.edu>
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 1991 14:30:37 -0500
I'd say make your sparc-1 your gateway. You might want to bring it up
to 16 or 24Mb of memory, but there's really no reason.
(The cs.widener.edu server was a Sparc1 until 3 months ago. It also did
NFS for 5 clients.)
Brendan
From: mike@inti.lbl.gov (Michael Helm)
To: bill@kepler.ucsd.edu (Bill Reynolds)
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Wed, 4 Dec 1991 12:51:32 PST
On Dec 4, 6:04pm, Bill Reynolds wrote:
> are using a sparc-2 as our gateway. We only have two sparc-2's and we
What do you mean by gateway? Do you mean a router? Or something
else?
** Our "gateway" doesn't run routed, it's really more of a bridge.
** It forwards packets to the campus router, which is smart enough to
** send those packets to our gateway that are destined for machines
** sitting behind it - BR
A SS-1 as router should be more than adequate to the task.
Of course, adding other duties to it affects this; it's
hard to quantify without really knowing the workload (both
routing & other jobs).
> 30 meg of memory). When I say "lightly loaded", I mean running X.
...
> We can put 16 or 32 meg of memory on the sparc-2, and the sparc-1 has
> 8 meg right now, but we can probably upgrade that if necessary.
I would think the 8 MB on the ss-1 would be running a little too lean,
which could affect it's ability to perform well.
From: kalli!kevin@fourx.Aus.Sun.COM (Kevin Sheehan {Consulting Poster Child})
To: fourx!kepler.ucsd.edu!bill@fourx.Aus.Sun.COM (Bill Reynolds)
Subject: Re: Sparc-1 or Sparc-2 a better gateway?
Date: Thu, 5 Dec 1991 08:41:25 EST
It is difficult to say without knowing what your network load is. You
can probably get a good idea with vmstat, and see what the system % of
CPU is for that box.
The difficulty is that SS1 and SS2 systems are pretty good at networking.
Routing packets doesn't normally eat much CPU, but it does eat some. A
lightly loaded SS<anything> can handle routing, the question is how much
of a routing load is there?
If it is a light load, why bother as the SS2 is fast enough. If it is
a heavier load, but not too heavy for the SS1, it is a win. If it is too
heavy for the SS1, then you should thing about using the SS1 as a place
to run the other jobs.
Sooo - takes the same number of cycles on either box, so why not just
run some of the 1-5 background jobs there as well?
l & h,
kev
Kevin Sheehan
Optimation Software Engineering
kalli!kevin@fourx.aus.sun.com
From: agw@math.canterbury.ac.nz (Allen Witt)
To: bill@kepler.ucsd.edu
Subject: Re: Sparc-1 or Sparc-2 a better router.
Date: Thu, 5 Dec 91 11:43:15 NZD
>1) Which is a better gateway, a loaded sparc-2 or a lightly loaded
>sparc-1? When is say "loaded", I mean running X (mit or openlook), and
>perhaps 1-5 background jobs of various sizes (I've seen them go up to
>30 meg of memory). When I say "lightly loaded", I mean running X.
Here we have subnetted our network of five SPARC2's, a SPARC1+, two
3/60's, nine 3/50's ( now running minimal kernels and swap with an
xserver) and 10 Xterminals, using a Sun 3/160 ( with 16Mb ) as a
router from the campus backbone ethernet. The 160 also boots a number
of the 3/50's, serves local executables to all Sun3's, is one
user's workstation and provides ALM serial ports for two printers
plus a number of dumb terminals. It's performance as a workstation
is not affected by it's performance as router and vice versa. In
fact the 60 meg tape drive it supports has a far greater effect,
when in use, on workstation performance. Of course this is for
relatively light traffic across the router - mail, news, remote
logins, telnet, ftp and some NFS mounts.
>2) How much of our computational power are we compromising by using
>the Sparc-2 as a gateway? Will all that traffic slow down our
>background jobs?
The peak routing loads I have observed on the 160 would be about
50% of cpu. A typical value in working hours would be around 5%.
Allen Witt email agw@math.canterbury.ac.nz
--
_______________________________________________________________________
Bill Reynolds |
bill@kepler.ucsd.edu |
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