View Full Version here: : Gigabit LAN
05-01-2009, 02:20 PM
I tackled a few astronomy projects over my Christmas break (now back at work), had a great time tinkering and getting long waiting jobs done.
One that I managed to sort out was upgrading the network cable from house to observatory from CAT5 to CAT6 such that I now have full gigabit network compatibility between house and observatory. It makes copying all the large amounts of imaging data a breeze! 7GB in 5 minutes was one example I watched a couple of days ago. That's a lot faster than I was getting over the previous 100 megabit/s connection!
It's making backups etc much faster. However now the bottleneck is the Pentium4 2.6GHz observatory PC who's harddrives go flat out while the network is doing a backup off/onto it!
05-01-2009, 03:35 PM
Nothing like a fast pipe. In my experience you probably didn't need to upgrade the cable, Gigabit ethernet works just fine on the majority of cat 5 installations.
05-01-2009, 05:47 PM
Using the previous cable it wasn't running at gigabit, would only work at 100 megabit. I think now that might have been due to plug wiring not the cable its self (as I understand it some older cat 5 cables are not wired to suit gigabit). So I think there's a good chance you're right, if I'd known to just re-wire the plugs on the cable. Also I've found several of my shorter off-the-shelf cables (1m, 2m, etc) are not gigabit compatible presumably due to the same wiring issue. So again, perhaps I didn't need to replace the cable and just needed to also replace those shorter ones :)
One other factor: the previous cable did have 7 odd years of direct exposure to sun in some parts (my laziness) and had pretty poor performance, perhaps as a result. So it's good to have a nice new heavier duty Cat 6 cable installed anyhow :) (better installation this time too :) )
06-01-2009, 01:28 AM
If I'm not mistaken Cat5e will run if not just as good as Cat6 between gigabit ports, however it is of course unshielded, so you'll want to be cautious of the proximity of electrical interference. Cat5 will only run at the 100Mbit although it is shielded.
I picked up two gigabit 8 port switches during Xmas for cheapy cheap.
Im currently running 15m Cat6 cable from inside computer to outside laptop near mount and remote desktop and file transfers are much better! :)
06-01-2009, 08:07 AM
Cat 5 cable includes four twisted pairs in a single cable jacket. This use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of interference is called crosstalk). It is most commonly used for 100 Mbit/s networks.
Cat 5e cable is an enhanced version of Cat 5 that adds specifications for far end crosstalk.Crossover is used for hub to hub, computer to computer, wherever two-way communication is necessary.
(cable of choice for now) :thumbsup:
Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz The cable contains four twisted copper wire pairs, just like earlier copper cable standards. Some Cat-6 cables are too large and may be difficult to attach to 8P8C connectors. Although Cat-6 is sometimes made with 23 gauge wire, this is not a requirement.
Cat-5/5e/6 cables are limited to a maximum of 100 m (328 ft) in length in use.
06-01-2009, 08:49 AM
We have a customer, an accountancy office (probably 600 cabled ends) that we have cabled over a period of years with cat5 and cat5E cable and hardware. They are running around 200 users all at full gigabit speeds.
FWIW Cat 5 spec, although having 8 wires, uses only 4 pins 1,2 and 3,6. The others can be split if you're short of cabled ends to allow 2 connections per cable, even for telephony etc on the spare pairs, we do this all the time where additional cabling is difficult/costly or time restraints apply.
Gigabit uses all 4 pairs of the cable..
In our experience it's best to avoid mixes of gigabit and 100mb hardware as IP traffic will sometimes bottleneck resulting in broadcast storms, causing complete lockups on the network, I've seen this problem on at least 2 sites. Some managed switches have storm prevention options and can lock out any offending ports.
06-01-2009, 11:58 PM
I'm on my 16th PC, and must say I love gigabit networks. I'm sorely temped to just add fast NAS's now for storage rather than keep adding newer, larger HHDs to individual machines.
If I ever wanted to go for raw speed, I'd skip a solid state NAS and go straight to a ZFS L2ARC platform (say with 2* SSD and 6 * SATA TB HDDs). But really who needs sustained 400+ mbytes / second throughput? Still being able to build such a platform for under $3K would give you enterprise class performance in the home - which is just amazing.
Bottom line - once you have more than 2-3 PCs in a house, and gigabit LANs a fast NAS becomes a really cheap and effective way to add shared storage.
07-01-2009, 08:27 AM
Yep I have a D-Link DNS-323 1 terabyte NAS box http://www.dlink.com/products/?pid=509 hooked to the 3 lappys best decision ever. holds all the shared files, backups, work in progress
Its not Star Trek Speed but it was pretty cheap and helps heaps with finding stuff in a central server.
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