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10/100 Mbps problem with router

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Anonymous
June 30, 2004 1:42:11 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Hi,

I have a problem with my small network. I've got 2 PCs connected to the
switch/router/ADSL modem (3 in 1). Router is 10/100 compatible. In these
PC's I've network cards 10/100. The PC-1 (win ME) is connected to the router
and it's working properly, it means I have 100 Mbps speed. The PC-2 is (Win
XP) also connected to this router, but it does not work properly, I get a
message 'The network kable is unpluged', but, in fact it's connected. If I
change speed in network card settings for 10 Mbps everything works properly.
What's wrong? Do you have same ideas?

Any help is greatly appreciated .
Thanks
Adam
Anonymous
June 30, 2004 1:42:12 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Adam T <trawa[NOSPAM]@jestsuper.pl> wrote:
> message 'The network kable is unpluged', but, in fact it's
> connected. If I change speed in network card settings for
> 10 Mbps everything works properly.

Did you make the cables yourself, or were they purchased
from a reliable manufacturer?

A machine that connects only a 10 Mbps sounds like "split
pair". These are almost guaranteed when people crimp their
own/friends cables.

-- Robert
Anonymous
June 30, 2004 3:02:56 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

U¿ytkownik "Robert Redelmeier" <redelm@ev1.net.invalid> napisa³ w wiadomo¶ci
news:SDkEc.9140$6E2.705@newssvr22.news.prodigy.com...
> Adam T <trawa[NOSPAM]@jestsuper.pl> wrote:
> > message 'The network kable is unpluged', but, in fact it's
> > connected. If I change speed in network card settings for
> > 10 Mbps everything works properly.
>
> Did you make the cables yourself, or were they purchased
> from a reliable manufacturer?

I made by myself.

> A machine that connects only a 10 Mbps sounds like "split
> pair". These are almost guaranteed when people crimp their
> own/friends cables.

What is split pair?

Adam
Related resources
Anonymous
June 30, 2004 3:02:57 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Adam T <trawa[NOSPAM]@jestsuper.pl> wrote:
> I made by myself.

I thought so. You almost certainly made a ...

> What is split pair?

Ethernet used balanced-pair signalling sent along twisted
pairs to reject noise. If the balanced signals are not
sent along a twisted pair (sent along different legs
of other pairs), there is no noise cancellation and the
condition is called a "split pair".

Electrons may be color blind, but they know who their dance
[twist] partners are -- me

There are 40,320 ways of wiring 8 conductors straight-thru.
Only 1,152 will give correct pairing for 100baseTX. None
of these is intuitive (pins 1&2 and 3&6 must be on pairs).
Only two (T-568A and T-568B) are blessed by standards.

Crimpers are are difficult to use correctly and should be
avoided by beginners. In addition to split pairs, they often
use the wrong plugs and get unreliable connections.

-- Robert
Anonymous
June 30, 2004 3:02:58 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

See:

http://duxcw.com/digest/Howto/network/cable/cable5.htm


"Robert Redelmeier" <redelm@ev1.net.invalid> wrote in message
news:inlEc.9847$T67.9178@newssvr24.news.prodigy.com...
> Adam T <trawa[NOSPAM]@jestsuper.pl> wrote:
> > I made by myself.
>
> I thought so. You almost certainly made a ...
>
> > What is split pair?
>
> Ethernet used balanced-pair signalling sent along twisted
> pairs to reject noise. If the balanced signals are not
> sent along a twisted pair (sent along different legs
> of other pairs), there is no noise cancellation and the
> condition is called a "split pair".
>
> Electrons may be color blind, but they know who their dance
> [twist] partners are -- me
>
> There are 40,320 ways of wiring 8 conductors straight-thru.
> Only 1,152 will give correct pairing for 100baseTX. None
> of these is intuitive (pins 1&2 and 3&6 must be on pairs).
> Only two (T-568A and T-568B) are blessed by standards.
>
> Crimpers are are difficult to use correctly and should be
> avoided by beginners. In addition to split pairs, they often
> use the wrong plugs and get unreliable connections.
>
> -- Robert
>
Anonymous
June 30, 2004 3:02:58 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

My experience is that cables 10' or shorter will work with a split pair.
The same split pair wiring at 40' to 50' won't work - at least with the
cable I was using. Results could vary according to the specific cable I
suppose.

No excuse for not wiring them correctly. It's not just copper, the twisted
pairs matter!

Also, use the EIA/TIA 568B standard color coding arrangement.

Why? Because if you don't you will end up confusing people and yourself.
How easy is it to figure out if a non-standard configuration doesn't split
pairs? Do you want to spend the time? Better to be able to inspect for a
*single* configuration.
(I just reworked an entire network that had nonstandard color coding but
ended up not having split pairs. What if I decided to fix one cable and
switched to the 568B standard at one end - left it unplugged - and then
fixed the other end and then plugged in both ends? What if my assessment of
the two ends being on the same cable was wrong? Now I have four bad ends in
the network - i.e. now two cables won't work....
In some cases when there was an obvious single connector in need of
replacement I kept the nonstandard arrangement to avoid this risk.....

What happens if you change from a nonstandard (but no split pairs) at the
ends to 568B, only to find that there's a coupler in the middle of the
cable(s) with the nonstandard wiring. Will it work? (Yes) Will anyone ever
be confused later? (Oh yes! Because now you have two cables that will only
work together and not anywhere else). Replace the coupler with a switch and
it might not work at all.

Fred

"Robert Redelmeier" <redelm@ev1.net.invalid> wrote in message
news:inlEc.9847$T67.9178@newssvr24.news.prodigy.com...
> Adam T <trawa[NOSPAM]@jestsuper.pl> wrote:
> > I made by myself.
>
> I thought so. You almost certainly made a ...
>
> > What is split pair?
>
> Ethernet used balanced-pair signalling sent along twisted
> pairs to reject noise. If the balanced signals are not
> sent along a twisted pair (sent along different legs
> of other pairs), there is no noise cancellation and the
> condition is called a "split pair".
>
> Electrons may be color blind, but they know who their dance
> [twist] partners are -- me
>
> There are 40,320 ways of wiring 8 conductors straight-thru.
> Only 1,152 will give correct pairing for 100baseTX. None
> of these is intuitive (pins 1&2 and 3&6 must be on pairs).
> Only two (T-568A and T-568B) are blessed by standards.
>
> Crimpers are are difficult to use correctly and should be
> avoided by beginners. In addition to split pairs, they often
> use the wrong plugs and get unreliable connections.
>
> -- Robert
>
Anonymous
June 30, 2004 5:32:34 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Fred Marshall <fmarshallx@remove_the_x.acm.org> wrote:
> I just reworked an entire network that had nonstandard
> color coding but ended up not having split pairs. What if
> I decided to fix one cable and switched to the 568B standard
> at one end - left it unplugged - and then fixed the other end
> and then plugged in both ends? What if my assessment of the
> two ends being on the same cable was wrong? Now I have four
> bad ends in the network - i.e. now two cables won't work....
> In some cases when there was an obvious single connector
> in need of replacement I kept the nonstandard arrangement
> to avoid this risk.....

Any work done on field crimps always has to check the pattern
used. Cut 3", strip jacket, untwist and inspect. Ring out
with a DVOM when in doubt or the whites don't have color trace.

Maintainability is an excellent reason to follow Structured
Wiring standards -- jacks with purchased patchcords. Cat5+
jacks all have color codes on them and it's easy to inspect
that -A or -B has been followed when reterminating. Patchcords
can be in any pattern because they're replaced as units.

A good network has never seen crimpers. A netadmin shouldn't
own any, and even a cabler will only use them on special jobs.

-- Robert
Anonymous
June 30, 2004 5:32:35 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"Robert Redelmeier" <redelm@ev1.net.invalid> wrote in message
news:ShzEc.9249$fM6.3582@newssvr22.news.prodigy.com...

> A good network has never seen crimpers. A netadmin shouldn't
> own any, and even a cabler will only use them on special jobs.

Robert,

How do you avoid this? I don't get it.

Are you suggesting that a damaged long-run cable be completely re-run just
so the connectors can be of a "manufactured" orgin?
How does one normally run cables that have connectors on them already?

Our market is made up of numerous small businesses often with multiple rooms
and cable runs as inaccessible as one might imagine. We often go into
attics, crawl spaces, etc. to get the job done. Not our target activity but
one necessary to meet the customer's needs. If it were new construction or
a big new installation then that would be different. Our local telephone
company does good work in that regard.

Patch panels aren't exactly common or even necessarily recommended. That is
not to say that physical integrity isn't important or dealt with.

We frequently run into poor workmanship at cable ends that requires the
cable ends be reworked. The cables have been run without connectors so that
feedthrough holes are often too small to accommodate connectors. etc. etc.
At our rates it would be unconscionable to run new cables all the time and
often waiting for an electrician or the telephone company to be called in is
unacceptable.

I have never worked in a "house" that didn't build cables..... Where does
this occur?

Fred
Anonymous
June 30, 2004 7:55:52 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Fred Marshall wrote:

>
> "Robert Redelmeier" <redelm@ev1.net.invalid> wrote in message
> news:ShzEc.9249$fM6.3582@newssvr22.news.prodigy.com...
>
>> A good network has never seen crimpers. A netadmin shouldn't
>> own any, and even a cabler will only use them on special jobs.
>
> Robert,
>
> How do you avoid this? I don't get it.
>
> Are you suggesting that a damaged long-run cable be completely re-run just
> so the connectors can be of a "manufactured" orgin?

A "long run cable" should not be terminated with anything that requires
crimpers.

> How does one normally run cables that have connectors on them already?

The only connectorized cables that have any business being used for data are
fiber optic.

> Our market is made up of numerous small businesses often with multiple
> rooms
> and cable runs as inaccessible as one might imagine. We often go into
> attics, crawl spaces, etc. to get the job done. Not our target activity
> but
> one necessary to meet the customer's needs. If it were new construction
> or
> a big new installation then that would be different. Our local telephone
> company does good work in that regard.
>
> Patch panels aren't exactly common or even necessarily recommended.

What do you mean "or even necessarily recommended"? To what standard are
these facilities cabled? The EIA/TIA standards that are the norm in the US
_require_ patch panels or some functional equivalent.

> That
> is not to say that physical integrity isn't important or dealt with.
>
> We frequently run into poor workmanship at cable ends that requires the
> cable ends be reworked. The cables have been run without connectors so
> that
> feedthrough holes are often too small to accommodate connectors. etc.
> etc.

Put jacks on them for God's sake. If it can't be removed without cutting
off a connector then it's permanent cabling and the standards require that
it be terminated with jacks at both ends.

> At our rates it would be unconscionable to run new cables all the
> time and often waiting for an electrician or the telephone company to be
> called in is unacceptable.

Don't know where you are but around here if you aren't an electrician and
you mess with premise wiring then it's a large fine.

> I have never worked in a "house" that didn't build cables..... Where does
> this occur?

In companies that had their cabling installed by somebody who knew what he
was doing.

> Fred

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
June 30, 2004 11:59:44 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Fred Marshall <fmarshallx@remove_the_x.acm.org> wrote:
> Are you suggesting that a damaged long-run cable be
> completely re-run just so the connectors can be of a
> "manufactured" orgin?

Nope. Long run fixed cable should be solid (plenum if necessary)
and run inside walls, chases, ceilings, floors, etc. It should
be terminated at the head end on a patchpanel (gang of jacks,
usually mounted as a 1U on an equipment rack). The field end
should be terminated on a walljack with nice pretty faceplate.
Phone service can go there too. Usually there are 2-4 wire runs
from the patchpanel to the faceplates, terminated on different
color jacks. Leave service loops at both ends.

From these jacks, connect to hub with a manufactured patchcord.
Likewise at the field end for the computer. Replace patchcords
as necessary.

> How does one normally run cables
> that have connectors on them already?

Only for masochists! Occasionally necessary for things like
projector SVGA feeds, then boot them up with tape.

> Our market is made up of numerous small businesses often with
> multiple rooms and cable runs as inaccessible as one might
> imagine. We often go into attics, crawl spaces, etc. to

This is normal. No matter how small, you still have a head
end and a patchpanel should go there. You can make a small
patchpanel from a double-gang plastic electrical box (cut
out the back) and 6 opening keystone faceplates. For more,
go with a block that mounts like a 66.

> Patch panels aren't exactly common or even necessarily
> recommended. That is not to say that physical integrity
> isn't important or dealt with.

Patchpanels are _required_ for Structured wiring (even a 66
block qualifies). Both ends of structural cabling must be fixed.
Userspace cabling is stranded, flexible and consummable.

> We frequently run into poor workmanship at cable ends
> that requires the cable ends be reworked. The cables

These were probably also run with solid cable which makes
very poor patchcords -- flexing produces work hardening
and intermittant connections.

To fix this installation reasonably inexpensively, do
not rerun cable if solid (and plenum if needed). Locate &
install patchpanel and field jacks on faceplates or surface
mount boxes. Add patchcords. Recrimping bad connectors
is a temporary fix.

> I have never worked in a "house" that didn't build
> cables..... Where does this occur?

We recently did 3000 runs, upgrading from IBM Type 1 cable.
1500 patchcords were purchased.

-- Robert
Anonymous
June 30, 2004 11:59:45 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Robert Redelmeier wrote:

> Fred Marshall <fmarshallx@remove_the_x.acm.org> wrote:
>> Are you suggesting that a damaged long-run cable be
>> completely re-run just so the connectors can be of a
>> "manufactured" orgin?
>
> Nope. Long run fixed cable should be solid (plenum if necessary)
> and run inside walls, chases, ceilings, floors, etc. It should
> be terminated at the head end on a patchpanel (gang of jacks,
> usually mounted as a 1U on an equipment rack). The field end
> should be terminated on a walljack with nice pretty faceplate.
> Phone service can go there too. Usually there are 2-4 wire runs
> from the patchpanel to the faceplates, terminated on different
> color jacks. Leave service loops at both ends.
>
> From these jacks, connect to hub with a manufactured patchcord.
> Likewise at the field end for the computer. Replace patchcords
> as necessary.
>
>> How does one normally run cables
>> that have connectors on them already?
>
> Only for masochists! Occasionally necessary for things like
> projector SVGA feeds, then boot them up with tape.
>
>> Our market is made up of numerous small businesses often with
>> multiple rooms and cable runs as inaccessible as one might
>> imagine. We often go into attics, crawl spaces, etc. to
>
> This is normal. No matter how small, you still have a head
> end and a patchpanel should go there. You can make a small
> patchpanel from a double-gang plastic electrical box (cut
> out the back) and 6 opening keystone faceplates. For more,
> go with a block that mounts like a 66.
>
>> Patch panels aren't exactly common or even necessarily
>> recommended. That is not to say that physical integrity
>> isn't important or dealt with.
>
> Patchpanels are _required_ for Structured wiring (even a 66
> block qualifies). Both ends of structural cabling must be fixed.
> Userspace cabling is stranded, flexible and consummable.
>
>> We frequently run into poor workmanship at cable ends
>> that requires the cable ends be reworked. The cables
>
> These were probably also run with solid cable which makes
> very poor patchcords -- flexing produces work hardening
> and intermittant connections.
>
> To fix this installation reasonably inexpensively, do
> not rerun cable if solid (and plenum if needed). Locate &
> install patchpanel and field jacks on faceplates or surface
> mount boxes. Add patchcords. Recrimping bad connectors
> is a temporary fix.
>
>> I have never worked in a "house" that didn't build
>> cables..... Where does this occur?
>
> We recently did 3000 runs, upgrading from IBM Type 1 cable.
> 1500 patchcords were purchased.

I'm curious--why "upgrade"? Anything CAT5 can do Type 1 can do as well or
better. Only downside is the media filters.
>
> -- Robert

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 1, 2004 1:07:24 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <cbv6460kih@news2.newsguy.com>,
J. Clarke <jclarke@nospam.invalid> wrote:
:What do you mean "or even necessarily recommended"? To what standard are
:these facilities cabled? The EIA/TIA standards that are the norm in the US
:_require_ patch panels or some functional equivalent.

I have a situation that I wonder if you might comment on?

Currently, my environment is professionally installed structured wiring,
with the drop cables run through to a punch block [I don't know the
technical name -- possibly a 66]. We then have, nearby, a second punch block
that has RJ connectors out the back end with the RJ's plugged into
the data infrastructure (e.g., switches.) The two punch blocks are
cross-connected with patch cords. Thus, any drop can be patched over
to any of the switch ports just by moving the patch cord.

In one of our telecomms rooms, we have been expanding the drops (with
corresponding punch block space, and we have expanded the number of
switches -- but we haven't yet installed the punch block that the
RJ connectors would normally run to.

One of my co-workers noticed that cables are available that have the
punch-block type connector on one end, and RJ type connector on the other.
They suggested that instead of installing the second punch block, that
to connect up the drops, that we just get some of the punch<->RJ cables
and go directly from the drop punch to the relevant switch port.
I've been hesitating, uncertain that we want to be running our
wiring in different ways in different places.

From a standards point of view, does it matter which of the two
approaches we use? Or from a signalling point of view? The expense
would be a bit lower with the punch<->RJ approach [wouldn't have to
get the new block installed, and patch cable prices are fairly similar.]
Or is it more a matter of cable neatness and cable strain -- the direct
punch<->RJ approach would end up with RJ wires running every which
way, whereas the current two-punch-block approach has the switch
cables all in neat bundles (except where we monkeyed with the ordering
for reasons we can't remember now...)
--
I predict that you will not trust this prediction.
Anonymous
July 1, 2004 1:07:25 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Walter Roberson wrote:

> In article <cbv6460kih@news2.newsguy.com>,
> J. Clarke <jclarke@nospam.invalid> wrote:
> :What do you mean "or even necessarily recommended"? To what standard are
> :these facilities cabled? The EIA/TIA standards that are the norm in the
> :US _require_ patch panels or some functional equivalent.
>
> I have a situation that I wonder if you might comment on?
>
> Currently, my environment is professionally installed structured wiring,
> with the drop cables run through to a punch block [I don't know the
> technical name -- possibly a 66]. We then have, nearby, a second punch
> block that has RJ connectors out the back end with the RJ's plugged into
> the data infrastructure (e.g., switches.) The two punch blocks are
> cross-connected with patch cords. Thus, any drop can be patched over
> to any of the switch ports just by moving the patch cord.

Let me make sure I understand what you're saying here. You say you have a
"second punch block that has RJ connectors out the back end". Are you
saying that you have cables punched down on the block with male RJ-45
connectors on them, or are you saying that you have a punchblock with RJ-45
female connectors on an attached panel, in other words a patch panel?

> In one of our telecomms rooms, we have been expanding the drops (with
> corresponding punch block space, and we have expanded the number of
> switches -- but we haven't yet installed the punch block that the
> RJ connectors would normally run to.
>
> One of my co-workers noticed that cables are available that have the
> punch-block type connector on one end, and RJ type connector on the other.
> They suggested that instead of installing the second punch block, that
> to connect up the drops, that we just get some of the punch<->RJ cables
> and go directly from the drop punch to the relevant switch port.
> I've been hesitating, uncertain that we want to be running our
> wiring in different ways in different places.
>
> From a standards point of view, does it matter which of the two
> approaches we use? Or from a signalling point of view?

From a signalling point of view the fewer discontinuities (not the right
word--for some reason I've gone blank on the right one--hate it when that
happens) in the cable you have the better--each one is a potential failure
point and each one degrades the signal a little. If you're going from
device to jack to punchblock to punchblock to switch that's 8
discontinuities. If you go from device to jack to punchblock to switch
then that's 7, which is slightly better. From a standards viewpoint I'm
going to let someone else answer--I don't have a current copy of 568 and
there have been some significant changes since mine was issued--I don't
want to give you a bum steer.

> The expense
> would be a bit lower with the punch<->RJ approach [wouldn't have to
> get the new block installed, and patch cable prices are fairly similar.]
> Or is it more a matter of cable neatness and cable strain -- the direct
> punch<->RJ approach would end up with RJ wires running every which
> way, whereas the current two-punch-block approach has the switch
> cables all in neat bundles (except where we monkeyed with the ordering
> for reasons we can't remember now...)



--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 1, 2004 11:53:11 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

J. Clarke wrote:

> Let me make sure I understand what you're saying here. You say you have a
> "second punch block that has RJ connectors out the back end". Are you
> saying that you have cables punched down on the block with male RJ-45
> connectors on them, or are you saying that you have a punchblock with RJ-45
> female connectors on an attached panel, in other words a patch panel?

I think I know the ones he wrote about. They are mostly used
by telephone (voice) people. If you consider a 110 block as a
plug, they are like a jack that fits over a pair of connection
points. With such connectors on both ends they can be used
as patch cables between 110 blocks. Ones with such connectors
on one end and an RJ connector on the other end also exist.

>>In one of our telecomms rooms, we have been expanding the drops (with
>>corresponding punch block space, and we have expanded the number of
>>switches -- but we haven't yet installed the punch block that the
>>RJ connectors would normally run to.

>>One of my co-workers noticed that cables are available that have the
>>punch-block type connector on one end, and RJ type connector on the other.
>>They suggested that instead of installing the second punch block, that
>>to connect up the drops, that we just get some of the punch<->RJ cables
>>and go directly from the drop punch to the relevant switch port.
>>I've been hesitating, uncertain that we want to be running our
>>wiring in different ways in different places.

>> From a standards point of view, does it matter which of the two
>>approaches we use? Or from a signalling point of view?

> From a signalling point of view the fewer discontinuities (not the right
> word--for some reason I've gone blank on the right one--hate it when that
> happens) in the cable you have the better--each one is a potential failure
> point and each one degrades the signal a little.

Impedance discontinuities. Similar to the way reflections
occur between materials with different index of refraction.

> If you're going from
> device to jack to punchblock to punchblock to switch that's 8
> discontinuities. If you go from device to jack to punchblock to switch
> then that's 7, which is slightly better. From a standards viewpoint I'm
> going to let someone else answer--I don't have a current copy of 568 and
> there have been some significant changes since mine was issued--I don't
> want to give you a bum steer.

It is somewhat complicated, but it depends on the amount of
impedance discontinuity and the length of the region with
a different impedance.

-- glen
Anonymous
July 1, 2004 11:53:12 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

glen herrmannsfeldt wrote:

> J. Clarke wrote:
>
>> Let me make sure I understand what you're saying here. You say you have
>> a
>> "second punch block that has RJ connectors out the back end". Are you
>> saying that you have cables punched down on the block with male RJ-45
>> connectors on them, or are you saying that you have a punchblock with
>> RJ-45 female connectors on an attached panel, in other words a patch
>> panel?
>
> I think I know the ones he wrote about. They are mostly used
> by telephone (voice) people. If you consider a 110 block as a
> plug, they are like a jack that fits over a pair of connection
> points. With such connectors on both ends they can be used
> as patch cables between 110 blocks. Ones with such connectors
> on one end and an RJ connector on the other end also exist.

He seems to be proposing the kind with the 110 (or whatever) connector on
one end and an RJ on the other end as an alternative to whatever it is that
he's doing now, but his description of what he's doing now is sufficiently
ambiguous that it's difficult (for me anyway) to tell whether what he's
proposing would be an improvement.

>>>In one of our telecomms rooms, we have been expanding the drops (with
>>>corresponding punch block space, and we have expanded the number of
>>>switches -- but we haven't yet installed the punch block that the
>>>RJ connectors would normally run to.
>
>>>One of my co-workers noticed that cables are available that have the
>>>punch-block type connector on one end, and RJ type connector on the
>>>other. They suggested that instead of installing the second punch block,
>>>that to connect up the drops, that we just get some of the punch<->RJ
>>>cables and go directly from the drop punch to the relevant switch port.
>>>I've been hesitating, uncertain that we want to be running our
>>>wiring in different ways in different places.
>
>>> From a standards point of view, does it matter which of the two
>>>approaches we use? Or from a signalling point of view?
>
>> From a signalling point of view the fewer discontinuities (not the right
>> word--for some reason I've gone blank on the right one--hate it when that
>> happens) in the cable you have the better--each one is a potential
>> failure point and each one degrades the signal a little.
>
> Impedance discontinuities. Similar to the way reflections
> occur between materials with different index of refraction.
>
>> If you're going from
>> device to jack to punchblock to punchblock to switch that's 8
>> discontinuities. If you go from device to jack to punchblock to switch
>> then that's 7, which is slightly better. From a standards viewpoint I'm
>> going to let someone else answer--I don't have a current copy of 568 and
>> there have been some significant changes since mine was issued--I don't
>> want to give you a bum steer.
>
> It is somewhat complicated, but it depends on the amount of
> impedance discontinuity and the length of the region with
> a different impedance.

They've put that in 568 now? Geez, maybe it's time to spring for a new
copy.

> -- glen

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 1, 2004 7:43:36 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

J. Clarke <jclarke@nospam.invalid> wrote:
> I'm curious--why "upgrade"? Anything CAT5 can do Type 1 can
> do as well or better. Only downside is the media filters.

Really? I thought IBM type 1 was only spec'd and rated to 16
MHz. We went from 10baseT to 100baseTX and needed the 100 MHz.

IBM type 1 is excellent cable and might have worked for shorter
runs, but we also have alot of runs near the 100m limit.

-- Robert
Anonymous
July 1, 2004 7:43:37 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Robert Redelmeier wrote:

> J. Clarke <jclarke@nospam.invalid> wrote:
>> I'm curious--why "upgrade"? Anything CAT5 can do Type 1 can
>> do as well or better. Only downside is the media filters.
>
> Really? I thought IBM type 1 was only spec'd and rated to 16
> MHz. We went from 10baseT to 100baseTX and needed the 100 MHz.

It is and it isn't. Originally it was rated to 16. IBM later had a change
in requirements and came out with a new "Type 1A" cable with a different
part number certified to 350--the cable itself does not appear to have been
changed at all, just the test. The standard connectors are rated to
30--IBM has new connector with a much higher rating--I forget the exact
number.

FWIW, IBM Type 1 was one of the target cables for 100TX and support for it
is in the spec, however finding devices that attach directly to it can be
problematical. Works fine with baluns though. The question is whether the
necessary baluns cost more than pulling CAT5E.

> IBM type 1 is excellent cable and might have worked for shorter
> runs, but we also have alot of runs near the 100m limit.
>
> -- Robert

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 1, 2004 7:56:28 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Walter Roberson <roberson@ibd.nrc-cnrc.gc.ca> wrote:
> Currently, my environment is professionally installed structured
> wiring, with the drop cables run through to a punch block
> [I don't know the technical name -- possibly a 66].

I would hope a 110 (horizontal rows of plastic blocks)
rather than a 66 (vertical columns of 4 metal teeth).
Most 66's (except Siemon's) are not Cat5 rated.

> We then have, nearby, a second punch block that has RJ
> connectors out the back end with the RJ's plugged into the
> data infrastructure (e.g., switches.) The two punch blocks
> are cross-connected with patch cords. Thus, any drop can
> be patched over to any of the switch ports just by moving
> the patch cord.

This is not unusual. The first punch block is a "consolidation
point" and permits different services (phone) to be split off,
or easy replacement if new equipment requires different jacks.
More common today is a blind faith in RJ45s and punching structural
cable directly onto rack patchpanels.

> One of my co-workers noticed that cables are available that
> have the punch-block type connector on one end, and RJ type
> connector on the other.

Yes, these exist but are expensive. I think they're mostly
used for testing, patching and 'temporary' setups. I have
heard of one installation that used them for everything.

-- Robert
Anonymous
July 1, 2004 9:41:36 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <cbvetg0uvp@news2.newsguy.com>,
J. Clarke <jclarke@nospam.invalid> wrote:
:Let me make sure I understand what you're saying here. You say you have a
:"second punch block that has RJ connectors out the back end". Are you
:saying that you have cables punched down on the block with male RJ-45
:connectors on them, or are you saying that you have a punchblock with RJ-45
:female connectors on an attached panel, in other words a patch panel?

If I have picked up the terminology correctly, then we currently
have this chain in our structured wiring system:


A) device NIC with RJ-45 female receptacle
B) cat5 cable with male RJ-45 on each end
C) labeled walljack with female RJ-45 receptacle
D) high-quality professionally-installed (AT&T certified) drop cables in
proper trays etc.
E) drop cables end at fixed labeled positions on a 110 punch block
F) patch cable with unknown type name. Each end has 4 flat vertical tines
that push between the plastic bumps of a 110 punch block. Similar such
endings but wider (more tines) endings are also available -- e.g. our
[few] ISDN lines use the wider version.
G) Above unknown patch cable is connected to any available labeled position
on a second 110 punch block.
H) the same kind of high quality cable as is used for the drop cables
comes out the back of the second 110 punch block, and runs over a metre
or two, each cable ending in a male RJ45.
I) These above are neatly bundled with little slack, each just long
enough to plug into sequential female RJ45 ports on our switches.
The expectation of the wirers was clearly that it would always be
the same male RJ45 plugged into any given switch port, with all
variability handled by which position on the drop 110 block that we
connect to which position on the switch 110 block.


Thus, if we wish to connect datajack D15 to switchport B22, we do so by
putting one of the those unknown flat-tine connectors between the
position that D15 is connected to on the drop 110 block, over to the
position that B22 is connected to on the switch 110 block.


We have installed additional drops (that terminate on 110 blocks),
and we have installed additional switches that we do NOT have a 110 block
for as yet.

My co-worker's proposal is that we do not install that switch 110 block
at all: that instead, we buy some new patch cables that have the
flat tines on one end, and have male RJ45 on the other end, and that then
when we wish to connect up a datajack, we do so by patching from the
drop 110 block position ("E", above) directly over to an available switch
port's female RJ45. That would be a different patch cable than "F",
and would skip "G" and "H" above. We would also lose the neatness
property mentioned in "I". At the moment, the cable tangles are
restricted to those unknown patch cables of point "G" above
(between the two 110 blocks); if we were to make the change, then
the tangles would exist between the positions on the drop 110 block ("E")
and the switchports.


:From a signalling point of view the fewer discontinuities (not the right
:word--for some reason I've gone blank on the right one--hate it when that
:happens) in the cable you have the better--each one is a potential failure
:p oint and each one degrades the signal a little. If you're going from
:D evice to jack to punchblock to punchblock to switch that's 8
:D iscontinuities. If you go from device to jack to punchblock to switch
:then that's 7, which is slightly better.

Good point.

I think perhaps the two points that I have been most concerned about are:

1) additional mechanical cable strain at the switch, considering that
we wouldn't be able to neatly bundle the new-type cables; and

2) whether the signal quality would be affected. The current cables
that plug into the switch are 8-wire Cat5. I don't know, though,
whether the patch cables that currently go between the 110 blocks
are technically Cat5 -- they are not very thick, and do not give me
the -impression- of being 8-wire cables [but they might be internally.]
If they are not really Cat5, then it would seem to me that they should
be kept as short as practical.

But then, I realize now that I don't know how they function at all; the
connectors that go onto the punch blocks are 4 tine, not 8 tine, which
would imply that there cannot be end-to-end signalling involving all 8 wires
of Cat5. 4 grounds, I guess? But if so, then would a cable with
the 4-tine connector on one end be able to provide proper Cat5 grounding?
Could we count on the switchport RJ45 end to provide any necessary
grounding?



As you can probably tell, I am inexperienced about physical-layer
issues. Not quite so inexperienced that I've never heard of NEXT,
but I haven't wired anything more than RS232.
--
Tenser, said the Tensor.
Tenser, said the Tensor.
Tension, apprehension,
And dissension have begun. -- Alfred Bester (tDM)
Anonymous
July 1, 2004 9:41:37 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Walter Roberson wrote:

> In article <cbvetg0uvp@news2.newsguy.com>,
> J. Clarke <jclarke@nospam.invalid> wrote:
> :Let me make sure I understand what you're saying here. You say you have
> :a
> :"second punch block that has RJ connectors out the back end". Are you
> :saying that you have cables punched down on the block with male RJ-45
> :connectors on them, or are you saying that you have a punchblock with
> :RJ-45 female connectors on an attached panel, in other words a patch
> :p anel?
>
> If I have picked up the terminology correctly, then we currently
> have this chain in our structured wiring system:
>
>
> A) device NIC with RJ-45 female receptacle
> B) cat5 cable with male RJ-45 on each end
> C) labeled walljack with female RJ-45 receptacle
> D) high-quality professionally-installed (AT&T certified) drop cables in
> proper trays etc.
> E) drop cables end at fixed labeled positions on a 110 punch block
> F) patch cable with unknown type name. Each end has 4 flat vertical tines
> that push between the plastic bumps of a 110 punch block. Similar such
> endings but wider (more tines) endings are also available -- e.g. our
> [few] ISDN lines use the wider version.

Most likely a standard 110 to 110 patch cable. See if the cable is
imprinted "CAT5".

> G) Above unknown patch cable is connected to any available labeled
> position on a second 110 punch block.
> H) the same kind of high quality cable as is used for the drop cables
> comes out the back of the second 110 punch block, and runs over a metre
> or two, each cable ending in a male RJ45.

Is that cable punched down on the 110 block? If so then it's trouble
waiting to happen--if it's stranded it won't make reliable contact on the
110, if it's solid then it's eventually going to break--may take a long
time if it's seldom disconnected but eventually it will go. Every time you
bend it even a little it work-hardens a little bit--eventually it
work-hardens to the point that it breaks instead of bending.

> I) These above are neatly bundled with little slack, each just long
> enough to plug into sequential female RJ45 ports on our switches.
> The expectation of the wirers was clearly that it would always be
> the same male RJ45 plugged into any given switch port, with all
> variability handled by which position on the drop 110 block that we
> connect to which position on the switch 110 block.
>
>
> Thus, if we wish to connect datajack D15 to switchport B22, we do so by
> putting one of the those unknown flat-tine connectors between the
> position that D15 is connected to on the drop 110 block, over to the
> position that B22 is connected to on the switch 110 block.
>
>
> We have installed additional drops (that terminate on 110 blocks),
> and we have installed additional switches that we do NOT have a 110 block
> for as yet.
>
> My co-worker's proposal is that we do not install that switch 110 block
> at all: that instead, we buy some new patch cables that have the
> flat tines on one end, and have male RJ45 on the other end, and that then
> when we wish to connect up a datajack, we do so by patching from the
> drop 110 block position ("E", above) directly over to an available switch
> port's female RJ45. That would be a different patch cable than "F",
> and would skip "G" and "H" above. We would also lose the neatness
> property mentioned in "I". At the moment, the cable tangles are
> restricted to those unknown patch cables of point "G" above
> (between the two 110 blocks); if we were to make the change, then
> the tangles would exist between the positions on the drop 110 block ("E")
> and the switchports.

This would from a signal propagation viewpoint be a better solution, also
likely to be a bit more reliable due to using the correct type of stranded
cable with the special connector taking care of making secure contact with
the 110 block.

> :From a signalling point of view the fewer discontinuities (not the right
> :word--for some reason I've gone blank on the right one--hate it when that
> :happens) in the cable you have the better--each one is a potential
> :failure
> :p oint and each one degrades the signal a little. If you're going from
> :D evice to jack to punchblock to punchblock to switch that's 8
> :D iscontinuities. If you go from device to jack to punchblock to switch
> :then that's 7, which is slightly better.
>
> Good point.
>
> I think perhaps the two points that I have been most concerned about are:
>
> 1) additional mechanical cable strain at the switch, considering that
> we wouldn't be able to neatly bundle the new-type cables; and

Wouldn't worry about it. Switches (at least rack-mountable ones--don't know
about the desktop cheapies) are designed to be used with patch cables
plugged into patch panels, which are typically rat's nests no matter how
neat you try to make them.

> 2) whether the signal quality would be affected. The current cables
> that plug into the switch are 8-wire Cat5. I don't know, though,
> whether the patch cables that currently go between the 110 blocks
> are technically Cat5 -- they are not very thick, and do not give me
> the -impression- of being 8-wire cables [but they might be internally.]
> If they are not really Cat5, then it would seem to me that they should
> be kept as short as practical.

A cross-connect cable doesn't have to be 4 pair. At least not in the spec
version that I have.

> But then, I realize now that I don't know how they function at all; the
> connectors that go onto the punch blocks are 4 tine, not 8 tine, which
> would imply that there cannot be end-to-end signalling involving all 8
> wires of Cat5. 4 grounds, I guess? But if so, then would a cable with
> the 4-tine connector on one end be able to provide proper Cat5 grounding?
> Could we count on the switchport RJ45 end to provide any necessary
> grounding?

100TX only needs 2 pairs. Each pair has a signal conductor and a ground.
If you go to gigabit then you'll need all 4 pairs. As long as you've got
the same pairing from one end to the other you've got no problems there.

> As you can probably tell, I am inexperienced about physical-layer
> issues. Not quite so inexperienced that I've never heard of NEXT,
> but I haven't wired anything more than RS232.

Bottom line on this is that aside from the issue of orderly appearance, if
the cable run from E to the switch is less than 5 meters, then to my way of
thinking your coworker's proposal would be the way to go. If it's more
than 5 meters then the "right" way to do it would be to go from E to a
patch panel and then use ordinary CAT5 patch cables from there to the
switch. Alternatively, you could go to a 110 block and use the type of
cables your coworker suggests.

In an ideal world, E would be a patch panel at the switch location instead
of a 110 block.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 6, 2004 11:52:04 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

J. Clarke wrote:

> glen herrmannsfeldt wrote:
>
>
>>J. Clarke wrote:

>>It is somewhat complicated, but it depends on the amount of
>>impedance discontinuity and the length of the region with
>>a different impedance.

> They've put that in 568 now? Geez, maybe it's time to spring for a new
> copy.

I don't know if it is in 568, but impedance discontinuity
is part of transmission line theory.

-- glen
Anonymous
July 6, 2004 11:52:05 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

glen herrmannsfeldt wrote:

> J. Clarke wrote:
>
>> glen herrmannsfeldt wrote:
>>
>>
>>>J. Clarke wrote:
>
>>>It is somewhat complicated, but it depends on the amount of
>>>impedance discontinuity and the length of the region with
>>>a different impedance.
>
>> They've put that in 568 now? Geez, maybe it's time to spring for a new
>> copy.
>
> I don't know if it is in 568, but impedance discontinuity
> is part of transmission line theory.

Well, yes it is, but 568 doesn't subsume the whole of transmission line
theory, it has a subset that may be implemented in such a manner as to be
testable by a cable installer on-site. And the one I have doesn't allow
for regions of different impedence, all cabling is 100 or 150 ohm +/- I
forget what and never the twain shall meet.

And generally unless there's a compelling reason not to, cabling should be
installed per 568.

> -- glen

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
July 7, 2004 4:48:47 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

J. Clarke wrote:
> glen herrmannsfeldt wrote:

(snip)

>>I don't know if it is in 568, but impedance discontinuity
>>is part of transmission line theory.

> Well, yes it is, but 568 doesn't subsume the whole of transmission line
> theory, it has a subset that may be implemented in such a manner as to be
> testable by a cable installer on-site. And the one I have doesn't allow
> for regions of different impedence, all cabling is 100 or 150 ohm +/- I
> forget what and never the twain shall meet.


The impedance depends on the wire spacing which doesn't always
stay as constant as could be desired. The rules on untwist length
also come from discontinuity effects. At low frequencies the
reflection from the two ends of a short discontinuity, such as
a short untwist region, almost cancel, such that the overall
effect is small. Even at 100MHz the wavelength is still 2m.

> And generally unless there's a compelling reason not to,
> cabling should be installed per 568.

I agree. But sometimes it is nice to know the real reason
for rules, other than the whim of the standard committee.

-- glen
!