[tech] Re: UCC uplink network upgrade

[Grahame Bowland]

On Thu, 2003-06-19 at 15:34, Nick Bannon wrote:
> On Thu, Jun 19, 2003 at 12:36:37PM +0800, David Cake wrote:
> > 	At this stage, I am going to try for 4 core fibre, with the 
> > second pairs purely as a backup.
> 
> That sounds like a good decision.
> 
> I talked to GR Services and no, blown fibre isn't going to work. The
> cable is going to have to go through a 20mm conduit and the 2 duct
> tubing (plus cladding) is 16mm, which is too close. They're going to
> have to pull out the 10Base2 RG-58 while they're at it.
> 
> Apparently the maintenance guys are unhappy about the conduit as well,
> but we're kinda stuck with it because there's others wires running
> through it, too.
> 
> So... we get one cable and if we ever want to upgrade it'll have to get
> pulled out and replaced, too.
> 
> It's tempting to go for high quality singlemode in that case and have
> overengineered 10km range 1000Base-LX links, but compatible with the
> other media converters that UCS is putting in. The installation cost
> will be similar (less for the cable, more for termination), but the
> endpoints would be 3x$797 dual 1000Base-LX modules instead of 3x$493
> dual 1000Base-SX modules.

There is no need to go single mode for this length of link. 1Gb works
fine on multi-mode, and 10Gb (should we ever want it) will probably work
too. I'm doubtful 10Gb will be necessary in the medium term - it's
definitely more than five years away from being a "must have".

The other thing to consider: media converters fail. They fail more often
than any other part of this equipment. You want the replacement cost to
be low, as you want to be able to acquire spares while you're waiting
for media converters to be replaced under warranty.

Also note that single mode is much more fussy about dust and such
things.

> > I don't care much about 100 
> > vs gig ether (though it seems important to Nick, I think there is a 
> > very little to gain from it), or about minor cost differences.
> > 	Cheers
> > 		David
> 
> I think that we've "needed" 100Mbps for a couple of years now. One can
> always make do, but lots of things, almost entirely outside of the
> UCC's control, have to line up to make any kind of upgrade possible.
> (e.g. simultaneous availability of upgrade funds for UCS, Guild and
> UCC, willingness to allow a major network outage, and a shared opinion
> that it's "worth it".)
> 
> So, given that this upgrade's going to have to last a while it seems
> worth paying a bit extra to get ahead of the curve. When it turns out
> that backbone gigabit is now so mainstream that it's a 8% _saving_ over
> the original DLink quote then it seems like we'd be mad not to. Even
> sticking to DLink it's still "only" a 50% extra cost per switch,
> because they're following the Cisco model of stiffing you on the
> optional modules and media converters. Upgrading later down the track
> means paying for all that, convincing everyone it's worthwhile again,
> _plus_ having no guarantee of finding the exact correct module for a
> two? year old switch by that point. More likely, it means replacing the
> switches. What's a fibre module's MTBF, anyway?
> 
> I'm personally willing to pay the upgrade costs from the original
> "adequate" solution to the "luxurious" 1000Base-SX/LX solution, though
> I do hope that others help out. The UCC can't afford to stick a lab's
> worth of $2000 desktops around the clubroom every year or two, but it
> can afford cool shared servers and a cool shared network.

Fair enough.

Nick, did you see in the committee minutes that we're not going to be
terminating fibre in the UCC machine room? I think it's a bad idea, as 
fibre has a MUCH lower tolerance for being kicked, trodden on, twisted, 
sneezed on and moved than your average piece of copper wire.

So we'll probably be limited to a 100baseT connection from the guild 
switch to the UCC machine room. This *really* doesn't matter as the 
Guild<->UWA is only 100Mb anyway, and we're unlikely to actually want 
to exchange files at high speed with the Guild. I reckon we can worry 
about a higher Guild<->UCC link at the same time we sort out the 
machine room issue.

If we can get 1000Base-SX for the same price (or lower) than 100BaseFX
then I reckon go for it. As I said, I'll have a look at the Alloy
tomorrow - the experience in UCS and ACS with the D-Links is that they
are somewhat dodgy.