Network topology used

[bbos360]

Any assistance would be greatly appreciated.

I have been recently asked to take charge of the network administation in our small company (10 employees with about 20 workstations 4 printers 2 scanners etc)

I have spent 1 solid month studying networking principles etc but seem to get stuck on 2 probably very basic questions!

office setup ->

the cat5e cabling across 3 floors enters the wiring rack in the basement and is connected to a 24 port patch panel. from here cables are run into a 24 Port switch (but some cables from the first patch panel run into a second patch panel and then the switch using some sort of splitting device?

questions:
a) Does this mean it is a STAR topology?
b) why do some cables go into the first patch panel (port 1 for eg) THEN from the same port (port 1) leave and enter the switch using a small splitter type device??


Thankyou for your time.

 

[bbos360]

sorry i rushed question b let me explain;

why do some cables from the first patch panel need to go into a second patch panel (port 1 for eg) and then from this same port (using a splitting device) a cable runs to a port on the switch???

Why cant a cable go from the first patch panel straight into the seitch?

thanks.

 

[QuiltedCamel]

That sounds like a suboptimal installation - the 'splitter' you're talking about - I guess it combines 2 pairs from each of 2 cables - which is sufficient for a 10BaseT network to operate half-duplex - when the time comes for 100BaseTX it may no longer work....

So there is no technical reason why you can't patch from any patch panel straight back to the switch, and in fact the presence of the splitter (as an interface, not as a splitter) may make the network fall outside of the Cat5 specifications because of the nubmer of joints in the cable.

There should be a maximum of 4 interfaces on the entire run - 1 at the switch to patch cord, 1 patch cord to patch panel, 1 patch panel to flylead, 1 flylead to equipment NIC.

By introducing the additional splitter(s) you've increased the number of interfaces by 2 for each splitter added.

Of course the number of interfaces is unlikely to have any ill effects, but in the event of suffering any ill effects it might be worth removing them to see if the effects persist.

 

[bbos360]

Thanks for that information, very helpfull. One quick point - from my description does this sound like a STAR topology network-> I am understanding loads more about networking but still find it hard to visual my network over three floors as a simple diagram flat.

 

[Bobg1]

The way you say the splitter is installed does not seem to make sense. It would seem to me that in the configuration you have, there might be 2 jacks some where connected to the same switch port, a problem waiting to happen as soon as something gets plugged into the other jack.
Now if you had said that there was a splitter in the patch panel coming from jack 1 and it was going to 2 different ports on the switch I would say that some one has split the cable to 2 jacks, which will work, although not recomended.
Either 10baseT or 100baseT, use 2 pair of wires. This type of config would have to also have bastard patch cords, another thing to cause problems.
You really should check and see where these things are going and try to get them out of the system. Normal configs will have one jack per cable per port from the switch. Anything else is asking for a problem.

 

[QuiltedCamel]

It sounds like a nightmare, but a star-connected nightmare... as Bobg1 says, these kludgy solutions have a habit of coming back to haunt you (it's bound to go pear-shaped for the most important person in the building) - the right thing to do is get it right first time.

If re-cabling is out of the question, then it might pay to rethink the siting of the switch - for example placing the switch on floor 2 rather than floor 1 might save any of this hideous cross floor patching.

 

[jimbopalmer]

'splitting device' does it have a vendor and model number?

two devices I have used that could be placed like you describe are 1) ethernet surge protectors and 2) Power Over Ethernet power supplies I tried to remain child-like, all I acheived was childish.

 

[bbos360]

theres about 4 of them. they are small 1.5 inch long 1 inch wide cream coloured blocks with 1 rj11 going in and 2 rj11's going out (i think this is rj11 - standard network cables)

 

[bbos360]

sorry - no model or no vendor - completely blank

 

[daronwilson]

Just a note on topology. It sounds like you are are referring to wiring topology, which is star, since all your cabling runs back to a central position. If you are referring to network topology, that is a different animal. Ethernet (traditionally) was a bus topology. Even though you had 10 wires from 10 stations comming back to a hub (traditionally) they were still on the same 'bus'. This only gets more confusing as we move forward in switches. However, what you have for a wiring topology is a star.

Splitters - you may not be splitting ethernet into two ports, but you may be adding a phone line or extension on the same cabling. Again, 10bT or 100bT either one will do fine on 2 pairs of wires, that is all that is connected (normally). So sometimes, someone wants a modem line or soemthing and they split the 4 pair wire out to use the other two pairs for something else. Or they could be split out for use as another ethernet port as you suspect. Standard ethernet cables terminate on an 8 pin modular plug, it is (incorrectly) commonly called an RJ-45 among network folks. RJ-11 would be one way of terminating your standard 4 conductor telephone wire. I think we need to be sure what you have before we can help you further with this, also do the two ports on the splitter both go to switch ports?

It sounds like perhaps the structured wiring system has been adapted to do a few other things rather than add the wires that should have been added. You are doing the right thing, first phase is discovery and documentation. Once you get that all down, you can see if you really have a problem.

Good Luck! It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[bbos360]

Very informative!

you got me thinking so I have been in the basement checking out the wiring and have found the following;

all cabling seems to go into the 1st 24 port patch panel and from here go into the switch. Fair enough seems ok.

However there is a second 24 port patch panel. on 3 occasions 2 different ports from the first patch panel basicaly go into 1 port on the second patch panel.

To answer your question the cable does not run into the switch on any of these three occurances of the 'splitter'

In the mean time I will be doing more research. Thankyou.

 

[bbos360]

also;

on the second patch panel, where one of these 'splitters' are located the letters isdn are penciled in, maybe this is hint as there is no writing anywhere else on anything - we used to have isdn internet but now use ADSL which i setup fine. We just have once machine used to 'isdn' things out.

If only people documented things correctly like some of us strive to the worl would be a much calmer less stressful place!

 

[Bobg1]

Sounds like the second patch panel is tied to the telco demark or telco switch. That makes more sense. What they are doing is bringing things to a central location and from there they can patch the jacks for what they need, be it a network connection from the switch or the isdn or dsl connection from the other patch panel. You could also route standard phone lines through the second patch panel if you needed to route them to one of the jacks.