Connecting different switches via fibre.

[Geoff]

I think this will work but I'd just like to double check with everyone else. I'd especially like to hear from anyone who has mixed networking equipment up like this. Firstly some background.

 

Currently we have a lot of 3com superstack kit. There is a 1Gbit fibre core connecting the IT block and the main building together via a 3com 4950 and 3com 4900.

 

These switches then feed various satellite cabs in key locations (Maths, LRC, 6th Form, Technology etc) that basically relate to a reasonable cluster of rooms with PCs in them. These are 3com 3300SM (possibly stacked via backplane fabric in some locations with 3com 3300XMs). These 3com 3300SM's are linked via 1Gbit fibre to either the 4950 in the Main block or the 4900 in IT.

 

Now I'm in the process of replacing this with HP Procurve kit. However I need to know that I can sucessfully connect a ProCurve 2650 (the model I've selected as a drop in replacement for our 3300's) to both the 4900 and the 4950 over fibre.

 

The ProCurve would be using a Gigabit-SX-LC in one of its Mini-GBIC ports. The 3com 4900 and 4950 have fibre ports which use MT-RJ type connectors (Rather than LC). I'm unsure of the grade or type of the fibre that's run between the switches, other than the fact it's been there a while (5+ years) and it's probably multimode.

[plexer]

I see no reason for it to not work Geoff.

 

Ben

[Finch7]

We have 3com 4950 and 4900sx.

 

They hook up to other 3com 4228G (these do not have mtrj connectors). All our kit is 3com though so I can't say anything about the hp stuff other than theres no reason why it shouldn't work.

[western]

Geoff it will work fine, the 3coms are SX Multimode. Problem is y are you not buying them of us you naughty boy!!

 

LC - MTRJ is just the connection and does not relate to whether it will work or not.

 

All the fibre back bone at your school is 50/125 as for your patch leads you would have to check

[m25man]

Your switches will normally work without question.

 

I would however take the oppourtunity to check the size/type of fibre used for your infrastructure interconnects.

Many schools I visit havm a right old mix of fibre lying around the place.

You may find both 50/125 and 62.5/125 used in different segments.

Many contractors use whatever is in the back of the van and some wouldn't know what the difference is anyway.

This is important, especially when dealing with exceptionally long runs.

 

In general Multimode fibre with SX candles is good for 250 mtrs, longer runs are possible with care. If you want longer reach use LX candles.

 

Using 62.5 patch leads with 50/125 core cable results in a 3db insertion loss at the patch panel (thats about 50% of your power) with the same loss at each end of your run would be like driving at night with 2 pairs of dark glasses on!

 

I have even seen single Mode patches used on Multimode panels.

 

If anyone wants a copy of my HP Fibre Training notes PM me.

[Geoff]

Alright, thanks for all that. Thanks for clearing up what the fibre is too western.