[tech] Re: UCC uplink network upgrade

[Nick Bannon]

On Thu, Jun 19, 2003 at 04:13:08PM +0800, Grahame Bowland wrote:
[...]
> 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".

10G Ethernet might seem blue-sky <grin> but it won't work on this link,
it'll only manage 26m-33m on the MM62.5 cable that's being planned. My
Clipsal/Gerards quote says that MM50 is actually a bit cheaper, so I'm
not sure why it isn't the default yet. <shrug> Anyway, at 82m, that
probably wouldn't reach either.

http://www.10gea.org/10GEA_FAQ_0602.pdf

10G Ethernet won't be a "must have", but I figure there'll be some
people playing with it on campus within a couple of years if not
before.

> 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.

True. That's why I think Alloy's good, and why I'm assuming the fibre
modules should all be doubles, and be interchangeable with each other.
Irritatingly enough, the standalone single interface media converters
cost more than the double interface switch modules.

The Cisco GBICs can at least be trusted to be available for a price,
but we assume the switch purchase price will be high enough for Cisco
not to be an option anyway.

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

<nod>

[...]
> 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.

Yes, I saw that - that's fine, as long as there's a spare fibre pair in
the inter-building link it doesn't really make any difference what's on
second floor, Cameron Hall. 100BaseT today, and if we wanted to change
anything, it's all easily accessible.

> 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 agree, but not for that reason. ::-)

 * There's no reason for UCC to upgrade to a high speed link to the Guild
   because the UCS link is slower, and hey, it's not like UCC even has
   high speed gear internally.

 * There's no reason for UCC to help the Guild to upgrade to a high
   speed link to UCS, because the UCC link is slower, and hey, it's not
   like the Guild even has high speed gear internally.

 * No-one wants to rip out everything at once and replace it because it
   would be risky, have a long outage and cost a heap, for a mere 10x
   speed increase that nobody really _needs_, anyway.

 * Therefore nobody upgrades anything until blind Freddy can see it's
   obsolete. ::-)

> I reckon we can worry about a higher Guild<->UCC link at the same
> time we sort out the machine room issue.

I'm sure we'll rearrange the clubroom half a dozen times by the time we
get a chance to pull new cable to the Guild... Assuming we don't lose
or change the clubroom that is, but it's as solid an arrangement as
it's ever likely to be right now, having just gone through the alarm
and power refits.

Nick.

-- 
   Nick Bannon   | "I made this letter longer than usual because
nick-sig at rcpt.to | I lack the time to make it shorter." - Pascal