DUX COMPUTER DIGEST

 

Site Search

Site Info

Home » Forums » Forum Archives » Networking and Internet Sharing » Topic # 1772

Network Segment Lengths
trumpetr Mar-16-02 06:33 PM
Am I understanding correctly that the 100m limit for ethernet for the 100BaseT standard and that there is a 300m limit for a 10BaseT network. I am trying to network a shop that is going to be right at 100m away from the router. If the router is 10/100 and the card at the other end is a 10/100 card with the components "downshift" to the 10 mode, or is the 100m hard no matter if I don't mind operating slower? (I did take a look at http://duxcw.com/digest/Howto/network/cable/index.htm and got the lengths from page 7 #1)

Also if I put a powered hub in will that give me another 100m of segment length, or is there some type of repeater ability that I need to be looking for? I'm looking at http://www.linksys.com/Products/product.asp?grid=24&prid=148
or
http://www.netgear.com/product_view.asp?xrp=2&yrp=4&zrp=13
or
http://www.netgear.com/categories.asp?xrp=2&yrp=6

Thanks for the great forums as always.

MC


1. RE: Network Segment Lengths
lbyard Mar-18-02 04:13 PM
In response to message 0
>I am trying to network a shop that is going to be right at 100m away from the router. If the router is 10/100 and the card at the other end is a 10/100 card with the components "downshift" to the 10 mode, or is the 100m hard no matter if I don't mind operating slower?

I'm not sure, but you may able to configure the cards/driver to operate only at 10 MHz, many allow it. The reason I am not sure is the 100 Meter limit on 100BASE-TX is imposed by timing limitations imposed by the time allowed to send packets down the pipe and the return of any collision signal (i.e., a 2-way trip), not necessarily by cable quality, etc. BTW, the 100 Meters is from absolute end point to absolute end point (in a LAN it would determine the maximum distance between the PCs that are furthest apart).

>Also if I put a powered hub in will that give me another 100m of segment length, or is there some type of repeater ability that I need to be looking for?

An Ethernet segment is an Ethernet network or a part of a larger network where devices such as PCs share the communications media in what known as a collision domain. Two computers networked together with a crossover cable (http://duxcw.com/digest/Howto/network/cable/cable1.htm ) comprise a simple Ethernet segment. As the two PCs do not have to listen for collisions that could be caused if additional PCs/devices were on the same segment, trying to transmit packets at the same time, both computers can send and receive data simultaneously using a full-duplex mode. More than two computers networked together with straight-thru cables and an Ethernet hub also form an Ethernet segment. They share the Ethernet segment using the Ethernet Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol. They operate at half duplex because they must listen for collisions with their receivers. An Ethernet switch forms separate, temporary Ethernet segments between it and the communicating devices, eliminates packet collisions, the need to listen for collisions, and allows full duplex operation between the devices connected to the switch. See http://duxcw.com/faq/network/hubsw.htm and http://duxcw.com/faq/ics/diffrout.htm for more info. The maximum distance between the end points (e.g., two PCs) of a 100BASE-TX segment is 100 Meters. This distance includes all cable, including jumpers and cable slack, between the end points. Ethernet hubs are repeaters, which come in two flavors: Class I and Class II. In a 100BASE-TX Ethernet, a simple Class I repeater supports only the devices connected to it and cannot be cascaded; i.e., to form more than one segment. In a 100BASE-TX Ethernet, a Class II repeater will support one hop (a hub to hub connection) to another Class II hub to form a network with two (overlapping) segments. Two cascaded hubs (or hub and switch) have a maximum network diameter of about 205 Meters. A Class II hub or switch (cost nearly the same) should work. The maximum distance between hub/switches is 100 meters. A switch by itself will stretch 200 meters (each PC is on its own segment) between end points. So, perhaps, another alternative is to move the router/switch so it is closer to the remote PC. http://duxcw.com/dcforum/jar.htm.

Larry


2. RE: Network Segment Lengths
trumpetr Mar-19-02 04:05 PM
In response to message 1
LAST EDITED ON Mar-19-02 AT 04:28 PM (EST)
 
Larry, Thanks for the help (a "tip" has been sent to help support the site, alway glad to support someone for quality information.)

I think that that gives me a really good understanding of how this all talks to each other. I will be using a Linksys BEFSR41 after the cable modem, then running right at the 100m limit to the shop office, I think that I am enough under the limit for it to work. If it dosn't seem to be working right I'll look for that class II switch to place in the shop at the entry point of the cable. Any reccomendations on what to get? I'm looking at both the netgear and linksys sites and don't find on their product data sheets weather their hubs/switches are classified class I or II. I actually can probabally move the modem and router about 20m closer to the shop if I need to (will definatally try this first before buing more hardware.)

Thanks again

MC


3. RE: Network Segment Lengths
lbyard Mar-19-02 04:33 PM
In response to message 2
Thank very much for the tip. That really helps now that advertising revenue is at an all time low (Iíll be lucky to make $70 from the whole web site this month). And just about all 4,000 plus pages are coded for banners.

>switches are classified class I or II.

That only applies to hubs. An Ethernet switch should work.

>Any recommendations on what to get?

I would get a switch. SMC, D-Link, Linksys, Telesis, 3Com, Intel, etc. I would look for a fanless unit.

The one thing you are more likely to have a problem with is that long cable. It has to be made with the correct cable and plugs and made and installed correctly or there will certainly be problems. I would use name-brand CAT 5e solid core cable. Itís available in 500 and 1,000 foot spools. Larry



4. RE: Network Segment Lengths
lbyard May-20-02 01:05 PM
In response to message 3
http://duxcw.com/digest/Howto/network/cable/cable7.htm was in error and has been corrected. The maximum segment length for 10BASE-T is the same as 100BASE-TX: 100 Meters (328 feet).

What is the problem that you are trying to solve? Larry


| Home | Guides | How to | Reviews | Online Store | FAQ | Forums | Forum Archives |
| Links | News | Newsletter | About Dux | Advertising | Contact Info | Privacy |