What the :censored: is going on...

[Oaktech]

A couple of weeks ago someone said they thought the internet was less snappy than usual, you know, you'd click on something, you'd wait a bit and everything would appear all at once.

 

That didn't sound right, so I did a couple of speedtests and lo and behold most computers were getting 95-105 (on a 100/100mbps) connection but only 3-15 up. I tried from the switch the router is connected to and got 95 both ways.

 

I tested the link and it seemed OK but I had a plan to install a multiple link anyway. I pulled in a test cable just with plugs on the end and it fixed it for most machines - 95 both ways. So I pulled in 2 new cables, created a trunk on the switches, connected and tested again - back to 95/10????

 

I reterminated the new links - no change.

I changed the patch cables - BOOM 95 both ways????

 

Now I'm testing every wired PC and anything that looks wrong I'm changing the patch cables and in the majority it's fixing it, so what the hell is going on!!

 

I've also got another line that refuses to run at gigabit even though it tests OK on a fluke tester, both patch cables are new, the client and the switch are known good and work as intended if patched elsewhere.

[njc235]

Have you checked your fibre patch cables in your network. You may have OM3 and OM1 mismatches which can produce the strangest results. I have come across similar symptoms before which were solved by matching fibre patch cables. The escape of light from a 50 to 65 nm (or vice-versa) connection will produce completely unpredictable results. Some people get away with it for years with no apparent effect then all of sudden, bam!

[Oaktech]

Have you checked your fibre patch cables in your network. You may have OM3 and OM1 mismatches which can produce the strangest results. I have come across similar symptoms before which were solved by matching fibre patch cables. The escape of light from a 50 to 65 nm (or vice-versa) connection will produce completely unpredictable results. Some people get away with it for years with no apparent effect then all of sudden, bam!

 

No fibre here yet... All copper.

[LytchettNM]

Some things to bear in mind using copper running at 1GB max cable run 100 meter's, and all 4 pairs are used making sure you use T-568A or B standard at both ends of the cable run.

The links between you core and edge switches you could set the ports to 1GB / full duplex and if you have or can run more than one cable between the core and edges switches and bind these ports with LACP as then will improve general speed when the switches are under load.

Make sure you edge switches connect back to your core switch and not daisy chained, a switch can make a decision about the condition of the connects and could drop the port from 1GB / full duplex to 100 Meg / half duplex and this sort of thing would feel like slow connections in one direction.

I tend to fix edge to core ports that run over copper to fixed not allowing auto detection as I have seen this cause intermittent problems, and if possible I'll run 2 to 4 cables and bind these ports with LACP as you get better bandwidth and automatic protection against port fails or someone unplugs something they should not.

[DMcCoy]

Is it a Netgear switch?

[Oaktech]

Is it a Netgear switch?

 

No they're all HP, some of them are rebranded 3com, some of them are real Pro-Curves.

[Oaktech]

Some things to bear in mind using copper running at 1GB max cable run 100 meter's, and all 4 pairs are used making sure you use T-568A or B standard at both ends of the cable run.

The links between you core and edge switches you could set the ports to 1GB / full duplex and if you have or can run more than one cable between the core and edges switches and bind these ports with LACP as then will improve general speed when the switches are under load.

Make sure you edge switches connect back to your core switch and not daisy chained, a switch can make a decision about the condition of the connects and could drop the port from 1GB / full duplex to 100 Meg / half duplex and this sort of thing would feel like slow connections in one direction.

I tend to fix edge to core ports that run over copper to fixed not allowing auto detection as I have seen this cause intermittent problems, and if possible I'll run 2 to 4 cables and bind these ports with LACP as you get better bandwidth and automatic protection against port fails or someone unplugs something they should not.

 

Thanks,

 

None of our runs are more than 100m, but a couple of places have daisy chains so I'll force them to gig/duplex. I'm in the process of getting quotes to install multiple links and re-route the daisy chains to more sensible layouts (at the moment in one building I have a switch 8 feet from the core vertically and the link travels 60m to the other side of the campus before it hits another switch.) so, fingers crossed the re-jig will help.

 

Basically, what I'm up against here is about 10 years of neglect during which time my predecessors were sold first a netgear, and then a ruckus wireless system and basically told 'you'll never need to worry about wires again'. I'm finding spliced cables. stuff still plugged into switches but chopped off and shorting above ceilings, some things wired A standard, some things wired B standard, archaic R&M patch panels which break when you patch stuff, nonsensical wiring layouts - like the one I mentined above, and just general wierdness.

 

I also have one line that will not run at gig with a PC on it despite it testing fine with a fluke tester and both the switch port and the PC working fine hung on other lines.

[LytchettNM]

Sound like a plan if I were you (and I was a few years ago) push for fibre links as these also provide electrical separation and go for new links from each edge cabinet back to you core cabinet or cabinets, this allows future proofing the school so you can upgrade, I would pull in a minimum or 24 fibres cores per fibre and for the shorter runs if you have the time and manpower you can buy pre-terminated cables which is cheaper and quicker than having a contractor in to do it for you. Edited November 23, 2016 by Techforyou

[JRowley]

We recently encountered an intermittent network fault which came down to some old Cat5 patch leads, replaced them with new Cat5E and it was resolved. It can sometimes be that simple.