Cable length of 100BT cat5 crossover cable?
Mike O'Connor
What's the maximum length of a cat5 crossover cable to connect two
100BT hubs? I've been going through various WWW pages and getting
different answers. Some say "5 meters". Some give various formulas
which imply that it depends on how populated your network is. Most
don't say and leave you with the assumption that it's 100 meters,
but I don't think that's the case.
What's the maximum length of a cat5 crossover cable to connect two
100BT hosts? Should that be 100 meters? If there's a different # for
hubs, how would this impact two crossover nodes and an isolated net?
--
Michael J. O'Connor | WWW: http://dojo.mi.org/~mjo/ | Email: m...@dojo.mi.org
InterNIC WHOIS: MJO | (has my PGP & Geek Code info) | Phone: +1 248-848-4481
Phil K
Max length between two ethernet as per standard devices is 100 meters. HUB
to HUB, NIC to HUB, NIC to NIC etc. The electronics don't know that they
are cross over or not.
Regards
--
Phil Kurek
Kurek Management Group
Strategic Network Consulting
Mike O'Connor <m...@dojo.mi.org> wrote in article
<9708311401...@dojo.mi.org>...
Dave Richkas
Mike O'Connor <m...@dojo.mi.org> wrote:
>What's the maximum length of a cat5 crossover cable to connect two
>100BT hubs?
It's 100 meters. The MDIX port on a hub has the same transmission
capabilities as a regular port.
NOjlund...@deltanet.com
In comp.dcom.cabling Dave Richkas <dric...@cts.com> wrote:
I've never seen where it said what the diff is re MDX or MDIX, or what
they mean. On some of our switches all the ports are MDIX. I guess they
are meant to be plugged into other hubs.
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William Smith
Mike O'Connor <m...@dojo.mi.org> wrote:
>What's the maximum length of a cat5 crossover cable to connect two
>100BT hubs?
It depends on the type of hub (type I or II repeater or switch), and
in the case of a repeater type, how much cable is connected to the
other stations on each of these two (you are only allowed two) hubs.
>What's the maximum length of a cat5 crossover cable to connect two
>100BT hosts?
Two nodes with a crossover cable (the simplest 'network') is 100
meters.
--
Willie Smith wp...@world.std.com N1...@amsat.org
#define NII Information SuperCollider
NOjlund...@deltanet.com
In comp.dcom.cabling Mike O'Connor <m...@dojo.mi.org> wrote:
: What's the maximum length of a cat5 crossover cable to connect two
: different answers. Some say "5 meters". Some give various formulas
: which imply that it depends on how populated your network is. Most
: don't say and leave you with the assumption that it's 100 meters,
: but I don't think that's the case.
: What's the maximum length of a cat5 crossover cable to connect two
: 100BT hosts? Should that be 100 meters? If there's a different # for
: hubs, how would this impact two crossover nodes and an isolated net?
It depends on what you are calling 'cable'. If you're talking about patch
cords, then the 568 specs say that the total length of the patch cords
should not exceed 10 meters. Regardless of whether or not they are
crossed over, I would say that this still applies.
If you're talking about the cable between the wall jack and the patch
panel, then the specs say 90 meters. I would say that this would still
aplly evn tho it's crossed over. But crossing over this cable is going to
give an error when tested. And in the future, it may coe back to haunt
you when you try to find a problem, or if you swap jacks around. Believe
me, it WILL come back and cause you grief.
You should use a crossover cable that is very short just to keep it from
being confused with regular straight-thru cables. I've been making
crossovers with a dual jack box. I try to stay away from the crossover
cables because of this confusion problem.
I thought about making one with a jack and a plug. Problem here is that
the usual stranded cable can't be seated reliably into the IDC connectors
of a jack. So what I did was unsolder the IDC connectors and solder the
stranded wires directly into the little PC board that holds the jack.
This is reliable but it is very time-consuming, and not a practical way to
do it. But it makes a great xover pigtail!
BTW, ALWAYS label the crossovers! ALWAYS!
: --
: Michael J. O'Connor | WWW: http://dojo.mi.org/~mjo/ | Email: m...@dojo.mi.org
: InterNIC WHOIS: MJO | (has my PGP & Geek Code info) | Phone: +1 248-848-4481
Paul Tichy
> What's the maximum length of a cat5 crossover cable to connect two
> 100BT hubs?
> What's the maximum length of a cat5 crossover cable to connect two
> 100BT hosts?
Whether you are concerned with a straight-wired or crossover cable is
irrelevant. The 802.3u spec has distance guidelines which are based on
electrical properties of typical UTP copper cable. I've compiled a
thumbnail guide of cabling specs for my own use which I've pasted in
below; not all of it is Fast Ethernet.
---
Common cabling, distance, timing and framing rules and standards
-------------------------------------------------------
TIA/EIA Cable Specifications
Category (CAT) Description
CAT 1 Telephone service and low speed data
CAT 2 ISDN and T1/E1
CAT 3 Data at up to 16 MHz
(including 10BASE-T at 10 Mbps, and 100BASE-T4 at 100
Mbps)
CAT 4 Data at up to 20 MHz
(including Token Ring at 16 Mbps,and 100BASE-T4)
CAT 5 Data at up to 100 MHz
(including 100BASE-TX and 100BASE-T4 at 100 Mbps)
---
Ethernet transmission distances
10Base5 500m
10Base2 185m
10BaseT 100m Cat3, ~150m Cat5 (a)
10BaseFL 2km on MM fiber; 25km on SM fiber
100BaseT 100m on 2 pair UTP Cat 5
100BaseT4 100m on 4 pair UTP Cat 3
100BaseFX 412m half duplex on MM fiber
100BaseFX 2km full duplex on MM fiber
100BaseFX 15-20km full duplex on SM fiber
Gigabit Pre-standard; see below
(a) 150m distance is approximated since 10BaseT signaling
properties are described electrically. While the electrical
propagation properties of typical Cat 5 cable allow 10BaseT
to extend about 150m, in creating such an extent, strict
Cat 5 compliance (as measured at 100mhz) is lost.
Ethernet minimum distances between nodes
10base5: 2.5m
10Base2: 0.5m
10BaseT: no minumum
Note also that all taps on 10Base5 should fall on points that are
multiples of 2.5m. Most ThickNet cables are marked with tap points.
---
Fast Ethernet repeater rules
Fast Ethernet repeater types:
Class I repeater
- Relaxed timing constraints within the repeater. <0.7us
transition delay. Makes media translation, stacking etc.
possible.
- One Class I repeater permitted between end stations.
Class II repeater
- Tighter timing constraints within the repeater. <0.46us
transition delay.
- Two repeaters permitted between end systems. If all the links
combine to <100m, may have 3 repeaters.
- Normally a 5m UTP or 6m fiber cable length is permitted between
cascaded repeaters. This link can be longer if end station
distances are shortened accordingly, such that the total
system diameter does not exceed 205m over copper, and no single
copper link exceeds 100m.
For quick visual identification a Fast Ethernet repeater should
display its class type with a Roman numeral (I or II) on a green
dot.
Fast Ethernet Repeater rules illustrated:
---- utp (Cat 5 for TX or Cat 3 for T4)
==== mm fiber
[DTE] end station (including Mac entities like routers, bridges and
switches)
[H] hub (repeater)
Direct connection of end stations (DTE's):
[DTE]--- 100m ---[DTE]
[DTE]=== 412m ===[DTE]
Using one Class I repeater:
[DTE]--- 100m ---[H]--- 100m ---[DTE]
[DTE]=== 136m ===[H]=== 136m ===[DTE]
Using one Class II repeater:
[DTE]--- 100m ---[H]--- 100m ---[DTE]
[DTE]=== 160m ===[H]=== 160m ===[DTE]
Using two Class II repeaters:
[DTE]--- 100m ---[H]-- 5m --[H]--- 100m ---[DTE]
[DTE]=== 111m ===[H]== 6m ==[H]=== 111m ===[DTE]
Topologies can be mixed so long as connection rules are respected.
E.g.,
Using two Class II repeaters:
[DTE]--- 100m ---[H]-- 5m --[H]=== 111m ===[DTE]
Transmission System Model 1 of the Ethernet standard provides
simplified guidelines.
Table of Maximum Cable Budgets (meters)
(From 802.3u specification)
Connection Type TX/T4 Fiber T4 & Fiber TX & Fiber
Direct 100 412 n/a n/a
One Class I repeater 200 272 231 b 260.8 b
One Class II repeater 200 320 n/a c 308.8 b
Two Class II repeaters 205 228 n/a c 216.2 d
b) Note: Assumes 100 meter copper link and one fiber link.
c) Not Applicable: T4 and FX cannot be linked with typical Class II
repeater.
d) Note: Assumes 105 meters of copper link and one fiber link.
A Fast Ethernet UTP link should never exceed 100m in length, due
to attenuation (signal loss) rather than timing considerations.
Using full duplex Fast Ethernet, the maximum distances are:
[DTE]=== 2km ===[DTE] multimode fiber
[DTE]=== 15-20km ===[DTE] singlemode fiber
---
Gigabit Ethernet transmission distance goals (pre-standard)
Copper 25m over twinax
1000BaseT Probably up to 100m using 4-pair Cat 5 UTP. The 1000Base-T
(UTP) work will not be part of the "first wave" of Gigabit
Ethernet; it is being developed in a separate effort, so
as not to delay initial standards deployment.
1000BaseF 500-550m full duplex on MM fiber, 2-3km full duplex on SM
fiber
1000BaseF 100m half duplex on MM fiber, shared LAN
Sources:
Scott Bradner, Senior Technical Consultant, Harvard
Rich Seifert, 802.3 committee chairman and editor
Gigabit Ethernet Alliance
http://www.gigabit-ethernet.org/compsum.html
---
10Mbps Ethernet, 100Mbps Fast Ethernet and Gigabit Ethernet
distance/timing
10Mbps 100Mbps 1Gbps
------ ------- -----
bit time 100ns 10ns 1ns
bit length
collision diameter (bit times) 512 512 4096
slot time (bit times) 512 512 4096
maximum round-trip delay 51.2us 5.12us 4.09us
maximum repeater-free diameter 4000m 412m 400m
minimum packet size 64 bytes 64 bytes 64
bytes*
maximum packet size 1518 bytes 1518 bytes 1518
bytes
maximum throughput, minimum packets 14,880pps 148,809pps
maximum throughput, maximum packets 812pps
* must be padded to 512 bytes on half duplex links (in order to get a
useful network diameter)
---
FDDI distance, station and framing rules
2km per hop over MM fiber
60km per hop over SM fiber
200km maximum ring circumference
500 station limit per ring
min frame size 25 bytes
max frame size 4500 bytes
---
ATM parameters
Cell size : 53 bytes
SONET and SDH
SONET (US) is based on the STS-1 at 51.84 Mb/s (for carrying T3),
and SDH (Europe) is based on the STM-1 at 155.52 Mb/s (for
carrying E4). They are not natively interoperable.
US STS and European STM levels :
US Europe Bit Rate (total)
----- ------ ----------------
STS-1 n/a 51.84 Mb/s
STS-3 STM-1 155.52 Mb/s
STS-12 STM-4 622.08 Mb/s
STS-24 STM-8 1244.16 Mb/s
STS-48 STM-16 2488.32 Mb/s
STS-192 STM-64 9953.28 Mb/s
---
Crossover Cabling Schemes
see: xover.txt
---
=======================================================
Paul Tichy 713-968-9184
Senior Systems Engineer, Newbridge Networks - Houston
pti...@us.newbridge.com
#include <std-disclaimer>
(Opinions expressed are purely my own, yada yada, etc.)
=======================================================
Tom Conover
Thamks Paul for a nice concise guide.
Peter Guenther
Mike O'Connor wrote:
>
> What's the maximum length of a cat5 crossover cable to connect two
> 100BT hubs?
It depends on the runs to the workstations fed by the hubs. The overall
maximum length of UTP with two repeaters between any two workstations on
a network is 205 metres. Thus, if you are allowing 100 m to all
workstations, the cascaded hubs cannot be more than 5m apart. If you set
a limit of 50m to workstations, then you can run 100m of cable betwen
hubs. If you are working on structured cabling limits, you really have
to budget on 5m.
> What's the maximum length of a cat5 crossover cable to connect two
> 100BT hosts? Should that be 100 meters? If there's a different # for
> hubs, how would this impact two crossover nodes and an isolated net?
Just an isolated crossover between NIC cards should be 100m.
> --
See our structured cabling guide and fast ethernet diagram for more
details.
--
Peter Guenther, Senior Engineer Comms/Andrew Boon Pty Ltd Consulting
Engineers
PO Box 308, North Hobart TAS 7002, AUS. Ph +61 3 6224 8277 fax +61 3
6224 8150
Structured Cabling Guide:
http://www.andrewboon.com.au/html/BOONSCS1.html
Fast Ethernet O'view Diagram:
http://www.andrewboon.com.au/images/100BaseT.GIF
Peter Guenther
Michael Shields wrote:
>
> > CAT 3 Data at up to 16 MHz
> > (including 10BASE-T at 10 Mbps, and 100BASE-T4 at 100
>
Yes. It runs at 10 MHz. It's straight RTZ Manchester coding.
--
Peter Guenther, Senior Engineer Comms/Andrew Boon Pty Ltd Consulting
Engineers
PO Box 308, North Hobart TAS 7002, AUS. Ph +61 3 6224 8277 fax +61 3
6224 8150
Web Home Page:- http://www.andrewboon.com.au Web resources:-
Structured Cabling Guide:
http://www.andrewboon.com.au/html/BOONSCS1.html
Building Comms Services Brief:
http://www.andrewboon.com.au/html/COMBRIEF.html
Fast Ethernet O'view Diagram:
http://www.andrewboon.com.au/images/100BaseT.GIF
ISP Selection Guide: http://www.andrewboon.com.au/html/ISPguide.html
Chuck Bolz
In article <87308160...@optional.cts.com>,
Dave Richkas <dric...@cts.com> wrote:
>Mike O'Connor <m...@dojo.mi.org> wrote:
>
>>What's the maximum length of a cat5 crossover cable to connect two
>>100BT hubs?
>
>capabilities as a regular port.
>
We found during worst-case interoperability testing that with some
samples of some vendors' PHYs we could only make 90 meters. I'd
be very cautious about that last 10 meters until the technology
matures a little more.
Any comments from the experts?
Chuck Bolz
Tektronix VND
Steve Mercer
On 10 Sep 1997 17:24:56 -0700, chu...@garnet.vnd.tek.com (Chuck Bolz)
wrote:
The IEEE 802.3u spec gives a maximum collision domain diameter of 205
meters. This is the total length of the 3 cable sements.
ie: (NIC to HUB) + (HUB to HUB) + (HUB to NIC) <= 205m
If you are using the maximum 100m segment on both NIC to HUB lengths,
this leaves only 5 meters for the link between hubs.
Steve Mercer
sme...@ositech.com