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View Full Version : RJ45 splitter for Ethernet - possible ?



P.Schuman
03-28-08, 10:56 AM
happen to run across this thread over on the Ethernet newsgroup -

Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
over on ebay (search RJ45 spliiter) that look like the telco 1-line 2-line
adapters,
but yet this guy (and the ebay description) says these "splitters" ....

Features:
a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point for
more conveniently use

b.. Increase the number of RJ45 network connections on an RJ45 outlet

c.. Compact design, feel free to enjoy your internet surfing

d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter, parallel
wiring

e.. Connector: 3 x RJ45 female

f.. 100% Brand New.

It doesn't even seem possible to have more "network connections"
by just splicing more Ethernet wires together vs a dumb hub ????

I could see if you were trying to split out the tip/ring (4/5) or power
(7/8)
but an Ethernet splitter ?????

--
----------------------------------
"If everything seems to be going well,
you have obviously overlooked something." - Steven Wright

Lloyd E. Sponenburgh
03-28-08, 11:03 AM
"P.Schuman" <pschuman_no_spam_me@interserv.com> fired this volley in
news:Ry8Hj.36354$J41.27658@newssvr14.news.prodigy.net:

> happen to run across this thread over on the Ethernet newsgroup -
>
> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
> over on ebay (search RJ45 spliiter) that look like the telco 1-line
> 2-line adapters,
> but yet this guy (and the ebay description) says these "splitters"
> ....
>
> Features:
> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point
> for
> more conveniently use
>
> b.. Increase the number of RJ45 network connections on an RJ45
> outlet
>
> c.. Compact design, feel free to enjoy your internet surfing
>
> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
> parallel
> wiring
>
> e.. Connector: 3 x RJ45 female
>
> f.. 100% Brand New.
>
> It doesn't even seem possible to have more "network connections"
> by just splicing more Ethernet wires together vs a dumb hub ????
>
> I could see if you were trying to split out the tip/ring (4/5) or
> power (7/8)
> but an Ethernet splitter ?????
>

The advertiser did not say "Ethernet network connections", he said
"network connections". Telephone systems are called "networks", also.

However, his presumption that its compact size will somehow enhance your
internet experience is both stupid AND leads one to believe he thinks you
CAN tee an ethernet connection.

LLoyd

News Reader
03-28-08, 11:09 AM
I've had splitters like this in my tool box for the past decade, but
have not actually implemented them.

Mine, are male on one side, and two female on the other.

Imagine that you plugged one into a wall jack at the location of a
workstation, and another in the closet where your switch resides.

This would support two Ethernet or FastEthernet devices at the
workstation location (e.g.: host, and network attached printer).

Each device would utilize two of the four pairs within the 8-wire (e.g.:
Cat 5e) cable.

This is however, not an appropriate thing to do from a performance
standpoint, and should not be standard practice.

If you were utilizing GigEthernet, I believe all four pairs are used to
support a single device, and therefore splitting would not be an option.


Best Regards,
News Reader

P.Schuman wrote:
> happen to run across this thread over on the Ethernet newsgroup -
>
> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
> over on ebay (search RJ45 spliiter) that look like the telco 1-line 2-line
> adapters,
> but yet this guy (and the ebay description) says these "splitters" ....
>
> Features:
> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point for
> more conveniently use
>
> b.. Increase the number of RJ45 network connections on an RJ45 outlet
>
> c.. Compact design, feel free to enjoy your internet surfing
>
> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter, parallel
> wiring
>
> e.. Connector: 3 x RJ45 female
>
> f.. 100% Brand New.
>
> It doesn't even seem possible to have more "network connections"
> by just splicing more Ethernet wires together vs a dumb hub ????
>
> I could see if you were trying to split out the tip/ring (4/5) or power
> (7/8)
> but an Ethernet splitter ?????
>

P.Schuman
03-28-08, 11:32 AM
News Reader wrote:
> I've had splitters like this in my tool box for the past decade, but
> have not actually implemented them.

ok - that pretty much answers the rest of your points

> Mine, are male on one side, and two female on the other.
>
> Imagine that you plugged one into a wall jack at the location of a
> workstation, and another in the closet where your switch resides.
>
> This would support two Ethernet or FastEthernet devices at the
> workstation location (e.g.: host, and network attached printer).

really - how ?

> Each device would utilize two of the four pairs within the 8-wire
> (e.g.: Cat 5e) cable.

really - how ?
considering that each Ethernet device normally expects pins 1/2 and 3/6
to be used ?
So, you would have to fabricate a custom cable for each of these
connections at each end
and then plug that cable into your cable-sharing RJ45 splitters..
1/2 = 1/2
3/6 = 3/4

1/2 = 5/6
3/6 = 7/8

> This is however, not an appropriate thing to do from a performance
> standpoint, and should not be standard practice.
>
> If you were utilizing GigEthernet, I believe all four pairs are used
> to support a single device, and therefore splitting would not be an
> option.
>
> Best Regards,
> News Reader
>
> P.Schuman wrote:
>> happen to run across this thread over on the Ethernet newsgroup -
>>
>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>> over on ebay (search RJ45 spliiter) that look like the telco 1-line
>> 2-line adapters,
>> but yet this guy (and the ebay description) says these "splitters"
>> .... Features:
>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point
>> for more conveniently use
>>
>> b.. Increase the number of RJ45 network connections on an RJ45
>> outlet c.. Compact design, feel free to enjoy your internet surfing
>>
>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
>> parallel wiring
>>
>> e.. Connector: 3 x RJ45 female
>>
>> f.. 100% Brand New.
>>
>> It doesn't even seem possible to have more "network connections"
>> by just splicing more Ethernet wires together vs a dumb hub ????
>>
>> I could see if you were trying to split out the tip/ring (4/5) or
>> power (7/8)
>> but an Ethernet splitter ?????

LR
03-28-08, 11:44 AM
P.Schuman wrote:
> News Reader wrote:
>> I've had splitters like this in my tool box for the past decade, but
>> have not actually implemented them.
>
> ok - that pretty much answers the rest of your points
>
>> Mine, are male on one side, and two female on the other.
>>
>> Imagine that you plugged one into a wall jack at the location of a
>> workstation, and another in the closet where your switch resides.
>>
>> This would support two Ethernet or FastEthernet devices at the
>> workstation location (e.g.: host, and network attached printer).
>
> really - how ?
>
>> Each device would utilize two of the four pairs within the 8-wire
>> (e.g.: Cat 5e) cable.
>
> really - how ?
> considering that each Ethernet device normally expects pins 1/2 and 3/6
> to be used ?
> So, you would have to fabricate a custom cable for each of these
> connections at each end
> and then plug that cable into your cable-sharing RJ45 splitters..
> 1/2 = 1/2
> 3/6 = 3/4
>
> 1/2 = 5/6
> 3/6 = 7/8
>

You do not need to fabricate any custom cables, you just use a standard
straight through cable for each connection. The splitters are used in
pairs, one on each end of a single run of cable.
<http://www.homestead.co.uk/productcategorydetail.aspx?CategoryID=51338&onspecialoffer=False>

News Reader
03-28-08, 11:51 AM
You are overlooking the key point.

The splitter is remapping pin placements.

Pins 1,2,3, and 6 on one of the female jacks are mapped to 1,2,3 and 6
on the male end, as you would expect.

The other female jack maps its pins 1,2,3, 6 to the other two wire pairs
(pins 4,5,7 and 8) on the male end.

Best Regards,
News Reader

P.Schuman wrote:
> News Reader wrote:
>> I've had splitters like this in my tool box for the past decade, but
>> have not actually implemented them.
>
> ok - that pretty much answers the rest of your points
>
>> Mine, are male on one side, and two female on the other.
>>
>> Imagine that you plugged one into a wall jack at the location of a
>> workstation, and another in the closet where your switch resides.
>>
>> This would support two Ethernet or FastEthernet devices at the
>> workstation location (e.g.: host, and network attached printer).
>
> really - how ?
>
>> Each device would utilize two of the four pairs within the 8-wire
>> (e.g.: Cat 5e) cable.
>
> really - how ?
> considering that each Ethernet device normally expects pins 1/2 and 3/6
> to be used ?
> So, you would have to fabricate a custom cable for each of these
> connections at each end
> and then plug that cable into your cable-sharing RJ45 splitters..
> 1/2 = 1/2
> 3/6 = 3/4
>
> 1/2 = 5/6
> 3/6 = 7/8
>
>> This is however, not an appropriate thing to do from a performance
>> standpoint, and should not be standard practice.
>>
>> If you were utilizing GigEthernet, I believe all four pairs are used
>> to support a single device, and therefore splitting would not be an
>> option.
>>
>> Best Regards,
>> News Reader
>>
>> P.Schuman wrote:
>>> happen to run across this thread over on the Ethernet newsgroup -
>>>
>>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>>> over on ebay (search RJ45 spliiter) that look like the telco 1-line
>>> 2-line adapters,
>>> but yet this guy (and the ebay description) says these "splitters"
>>> .... Features:
>>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point
>>> for more conveniently use
>>>
>>> b.. Increase the number of RJ45 network connections on an RJ45
>>> outlet c.. Compact design, feel free to enjoy your internet surfing
>>>
>>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
>>> parallel wiring
>>>
>>> e.. Connector: 3 x RJ45 female
>>>
>>> f.. 100% Brand New.
>>>
>>> It doesn't even seem possible to have more "network connections"
>>> by just splicing more Ethernet wires together vs a dumb hub ????
>>>
>>> I could see if you were trying to split out the tip/ring (4/5) or
>>> power (7/8)
>>> but an Ethernet splitter ?????
>
>

DTC
03-28-08, 11:56 AM
P.Schuman wrote:
> happen to run across this thread over on the Ethernet newsgroup -
>
> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
> over on ebay (search RJ45 spliiter) that look like the telco 1-line 2-line
> adapters,
> but yet this guy (and the ebay description) says these "splitters" ....

What he doesn't tell you is that you need TWO of these things.
One at the wall plate and one at the back room hub.

You're better off simply dropping in a small $20 hub at the wall
plate location.

P.Schuman
03-28-08, 12:04 PM
AH HAH -
YES.... IF the description mentions that the pins are re-mapped,
then we have a solution -
BUT only if deployed in pairs.
I used to use them for piggyback of Phone + Ethernet + IBM 3270
on a single 8-wire RJ45 jack installed to each cubicle.

The original thread was basically using ONE of these "splitters"
to just walk up to any RJ45 jack, plug in - and now have TWO jacks and TWO
computers connected.
OR - using a "splitter" to run an Ethernet cable between several computers,
and basically T-connect them - as in the old coax days.

BTW - most of the eBay listings I clicked on made no mention of any
re-mapping,
so they might just be parallel RJ45's or ?? who knows what.

News Reader wrote:
> You are overlooking the key point.
>
> The splitter is remapping pin placements.
>
> Pins 1,2,3, and 6 on one of the female jacks are mapped to 1,2,3 and 6
> on the male end, as you would expect.
>
> The other female jack maps its pins 1,2,3, 6 to the other two wire
> pairs (pins 4,5,7 and 8) on the male end.
>
> Best Regards,
> News Reader
>
> P.Schuman wrote:
>> News Reader wrote:
>>> I've had splitters like this in my tool box for the past decade, but
>>> have not actually implemented them.
>>
>> ok - that pretty much answers the rest of your points
>>
>>> Mine, are male on one side, and two female on the other.
>>>
>>> Imagine that you plugged one into a wall jack at the location of a
>>> workstation, and another in the closet where your switch resides.
>>>
>>> This would support two Ethernet or FastEthernet devices at the
>>> workstation location (e.g.: host, and network attached printer).
>>
>> really - how ?
>>
>>> Each device would utilize two of the four pairs within the 8-wire
>>> (e.g.: Cat 5e) cable.
>>
>> really - how ?
>> considering that each Ethernet device normally expects pins 1/2
>> and 3/6 to be used ?
>> So, you would have to fabricate a custom cable for each of these
>> connections at each end
>> and then plug that cable into your cable-sharing RJ45 splitters..
>> 1/2 = 1/2
>> 3/6 = 3/4
>>
>> 1/2 = 5/6
>> 3/6 = 7/8
>>
>>> This is however, not an appropriate thing to do from a performance
>>> standpoint, and should not be standard practice.
>>>
>>> If you were utilizing GigEthernet, I believe all four pairs are used
>>> to support a single device, and therefore splitting would not be an
>>> option.
>>>
>>> Best Regards,
>>> News Reader
>>>
>>> P.Schuman wrote:
>>>> happen to run across this thread over on the Ethernet newsgroup -
>>>>
>>>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>>>> over on ebay (search RJ45 spliiter) that look like the telco 1-line
>>>> 2-line adapters,
>>>> but yet this guy (and the ebay description) says these "splitters"
>>>> .... Features:
>>>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily,
>>>> point for more conveniently use
>>>>
>>>> b.. Increase the number of RJ45 network connections on an RJ45
>>>> outlet c.. Compact design, feel free to enjoy your internet surfing
>>>>
>>>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
>>>> parallel wiring
>>>>
>>>> e.. Connector: 3 x RJ45 female
>>>>
>>>> f.. 100% Brand New.
>>>>
>>>> It doesn't even seem possible to have more "network connections"
>>>> by just splicing more Ethernet wires together vs a dumb hub ????
>>>>
>>>> I could see if you were trying to split out the tip/ring (4/5) or
>>>> power (7/8)
>>>> but an Ethernet splitter ?????

News Reader
03-28-08, 12:17 PM
The seller is not necessarily trying to deceive anyone.

Many products are promoted based on features, without any reference to
how to implement the functionality.

The eBay post was probably like most news posts, incomplete.

Best Regards,
News Reader

P.Schuman wrote:
> AH HAH -
> YES.... IF the description mentions that the pins are re-mapped,
> then we have a solution -
> BUT only if deployed in pairs.
> I used to use them for piggyback of Phone + Ethernet + IBM 3270
> on a single 8-wire RJ45 jack installed to each cubicle.
>
> The original thread was basically using ONE of these "splitters"
> to just walk up to any RJ45 jack, plug in - and now have TWO jacks and TWO
> computers connected.
> OR - using a "splitter" to run an Ethernet cable between several computers,
> and basically T-connect them - as in the old coax days.
>
> BTW - most of the eBay listings I clicked on made no mention of any
> re-mapping,
> so they might just be parallel RJ45's or ?? who knows what.
>
> News Reader wrote:
>> You are overlooking the key point.
>>
>> The splitter is remapping pin placements.
>>
>> Pins 1,2,3, and 6 on one of the female jacks are mapped to 1,2,3 and 6
>> on the male end, as you would expect.
>>
>> The other female jack maps its pins 1,2,3, 6 to the other two wire
>> pairs (pins 4,5,7 and 8) on the male end.
>>
>> Best Regards,
>> News Reader
>>
>> P.Schuman wrote:
>>> News Reader wrote:
>>>> I've had splitters like this in my tool box for the past decade, but
>>>> have not actually implemented them.
>>> ok - that pretty much answers the rest of your points
>>>
>>>> Mine, are male on one side, and two female on the other.
>>>>
>>>> Imagine that you plugged one into a wall jack at the location of a
>>>> workstation, and another in the closet where your switch resides.
>>>>
>>>> This would support two Ethernet or FastEthernet devices at the
>>>> workstation location (e.g.: host, and network attached printer).
>>> really - how ?
>>>
>>>> Each device would utilize two of the four pairs within the 8-wire
>>>> (e.g.: Cat 5e) cable.
>>> really - how ?
>>> considering that each Ethernet device normally expects pins 1/2
>>> and 3/6 to be used ?
>>> So, you would have to fabricate a custom cable for each of these
>>> connections at each end
>>> and then plug that cable into your cable-sharing RJ45 splitters..
>>> 1/2 = 1/2
>>> 3/6 = 3/4
>>>
>>> 1/2 = 5/6
>>> 3/6 = 7/8
>>>
>>>> This is however, not an appropriate thing to do from a performance
>>>> standpoint, and should not be standard practice.
>>>>
>>>> If you were utilizing GigEthernet, I believe all four pairs are used
>>>> to support a single device, and therefore splitting would not be an
>>>> option.
>>>>
>>>> Best Regards,
>>>> News Reader
>>>>
>>>> P.Schuman wrote:
>>>>> happen to run across this thread over on the Ethernet newsgroup -
>>>>>
>>>>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>>>>> over on ebay (search RJ45 spliiter) that look like the telco 1-line
>>>>> 2-line adapters,
>>>>> but yet this guy (and the ebay description) says these "splitters"
>>>>> .... Features:
>>>>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily,
>>>>> point for more conveniently use
>>>>>
>>>>> b.. Increase the number of RJ45 network connections on an RJ45
>>>>> outlet c.. Compact design, feel free to enjoy your internet surfing
>>>>>
>>>>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
>>>>> parallel wiring
>>>>>
>>>>> e.. Connector: 3 x RJ45 female
>>>>>
>>>>> f.. 100% Brand New.
>>>>>
>>>>> It doesn't even seem possible to have more "network connections"
>>>>> by just splicing more Ethernet wires together vs a dumb hub ????
>>>>>
>>>>> I could see if you were trying to split out the tip/ring (4/5) or
>>>>> power (7/8)
>>>>> but an Ethernet splitter ?????
>
>

gfretwell@aol.com
03-28-08, 01:51 PM
On Fri, 28 Mar 2008 12:09:53 -0400, News Reader <user@domain.null>
wrote:

>I've had splitters like this in my tool box for the past decade, but
>have not actually implemented them.
>
>Mine, are male on one side, and two female on the other.
>
>Imagine that you plugged one into a wall jack at the location of a
>workstation, and another in the closet where your switch resides.
>
>This would support two Ethernet or FastEthernet devices at the
>workstation location (e.g.: host, and network attached printer).
>
>Each device would utilize two of the four pairs within the 8-wire (e.g.:
>Cat 5e) cable.
>
>This is however, not an appropriate thing to do from a performance
>standpoint, and should not be standard practice.
>
>If you were utilizing GigEthernet, I believe all four pairs are used to
>support a single device, and therefore splitting would not be an option.
>
>
>Best Regards,
>News Reader
>
>P.Schuman wrote:
>> happen to run across this thread over on the Ethernet newsgroup -
>>
>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>> over on ebay (search RJ45 spliiter) that look like the telco 1-line 2-line
>> adapters,
>> but yet this guy (and the ebay description) says these "splitters" ....
>>
>> Features:
>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point for
>> more conveniently use
>>
>> b.. Increase the number of RJ45 network connections on an RJ45 outlet
>>
>> c.. Compact design, feel free to enjoy your internet surfing
>>
>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter, parallel
>> wiring
>>
>> e.. Connector: 3 x RJ45 female
>>
>> f.. 100% Brand New.
>>
>> It doesn't even seem possible to have more "network connections"
>> by just splicing more Ethernet wires together vs a dumb hub ????
>>
>> I could see if you were trying to split out the tip/ring (4/5) or power
>> (7/8)
>> but an Ethernet splitter ?????
>>

News has the right answer. These splitters break out the 4 pairs into
two sets of two. There is no problem with this in the ethernet
standard (cat 5 can support 2 ethernet lans if they are 10/100)
Don't do this with POTS phones unless you can live with the errors
when the phone rings.
It will not work with gigabit LAN, that needs all 4 pairs.

BTW I am doing this at my house and it works fine. (no packet errors)

lawrence.jones@siemens.com
03-28-08, 02:05 PM
News Reader <user@domain.null> wrote:
>
> Mine, are male on one side, and two female on the other.

The ones I see on eBay are female on both sides.

> Imagine that you plugged one into a wall jack at the location of a
> workstation, and another in the closet where your switch resides.

That would be true if they split the pairs, but the descriptions of the
ones on eBay all say "parallel wiring", which implies that they don't.
I can't imagine that they are of any practical use whatsoever for
Ethernet.

-Larry Jones

You don't get to be Mom if you can't fix everything just right. -- Calvin

Robert Redelmeier
03-28-08, 02:13 PM
In comp.dcom.cabling P.Schuman <pschuman_no_spam_me@interserv.com> wrote in part:
> The original thread was basically using ONE of these "splitters"
> to just walk up to any RJ45 jack, plug in - and now have TWO
> jacks and TWO computers connected. OR - using a "splitter" to
> run an Ethernet cable between several computers, and basically
> T-connect them - as in the old coax days.

Yes, I remember a passive circuit for 10baseT that might
work under lucky conditions (short run, short patches).
No guarantees of any kind (including router port-burnout).
I doubt it would work at 100, and hubs are too cheap for
passive to be worth the risk.

-- Robert

News Reader
03-28-08, 03:40 PM
The genders really aren't relevant, as long as the four pairs are fanned
out correctly. The version I have is usable when you are accessing the
cable run via a wall jack. If I had access to the raw end of the cable,
then I would want the genders per the product the guy is selling.

Your interpretation of his use of the term "parallel wiring" may be
correct. However, it may also be that the seller has a poor
understanding of the english language, or even the functionality of the
product he is selling.

I'm not condoning the use of splitters, I'm only suggesting that a
legitimate product exists, that maybe the product he is selling is an
example of the legit product, and that maybe he has represented its use
incorrectly.

I'd be interested in reading the seller's e-bay description, if somebody
wanted to post it here.

Best Regards,
News Reader

lawrence.jones@siemens.com wrote:
> News Reader <user@domain.null> wrote:
>> Mine, are male on one side, and two female on the other.
>
> The ones I see on eBay are female on both sides.
>
>> Imagine that you plugged one into a wall jack at the location of a
>> workstation, and another in the closet where your switch resides.
>
> That would be true if they split the pairs, but the descriptions of the
> ones on eBay all say "parallel wiring", which implies that they don't.
> I can't imagine that they are of any practical use whatsoever for
> Ethernet.
>
> -Larry Jones
>
> You don't get to be Mom if you can't fix everything just right. -- Calvin

lawrence.jones@siemens.com
03-28-08, 03:47 PM
gfretwell@aol.com wrote:
>
> Don't do this with POTS phones unless you can live with the errors
> when the phone rings.

Since 10Base-T and 100Base-TX were both designed to coexist with phone
lines in the same cable, that shouldn't be a problem.

-Larry Jones

Start tying the sheets together. We'll go out the window. -- Calvin

News Reader
03-28-08, 04:05 PM
The product I have had in my toolbox for the past decade can be found at:

http://www.hubbellpremisewiring.com/catalog/model_BR851D.htm

I have not reviewed the info at this link, and have not confirmed what
Category they are.

They are probably Cat 3 (suitable for Ethernet only).

Maybe they have a Cat 5e version suitable for FastEthernet, but you
would have to research that for yourself.

Best Regards,
News Reader

News Reader wrote:
> I've had splitters like this in my tool box for the past decade, but
> have not actually implemented them.
>
> Mine, are male on one side, and two female on the other.
>
> Imagine that you plugged one into a wall jack at the location of a
> workstation, and another in the closet where your switch resides.
>
> This would support two Ethernet or FastEthernet devices at the
> workstation location (e.g.: host, and network attached printer).
>
> Each device would utilize two of the four pairs within the 8-wire (e.g.:
> Cat 5e) cable.
>
> This is however, not an appropriate thing to do from a performance
> standpoint, and should not be standard practice.
>
> If you were utilizing GigEthernet, I believe all four pairs are used to
> support a single device, and therefore splitting would not be an option.
>
>
> Best Regards,
> News Reader
>
> P.Schuman wrote:
>> happen to run across this thread over on the Ethernet newsgroup -
>>
>> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
>> over on ebay (search RJ45 spliiter) that look like the telco 1-line
>> 2-line adapters,
>> but yet this guy (and the ebay description) says these "splitters" ....
>>
>> Features:
>> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point
>> for more conveniently use
>>
>> b.. Increase the number of RJ45 network connections on an RJ45 outlet
>>
>> c.. Compact design, feel free to enjoy your internet surfing
>>
>> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter,
>> parallel wiring
>>
>> e.. Connector: 3 x RJ45 female
>>
>> f.. 100% Brand New.
>>
>> It doesn't even seem possible to have more "network connections"
>> by just splicing more Ethernet wires together vs a dumb hub ????
>>
>> I could see if you were trying to split out the tip/ring (4/5) or
>> power (7/8)
>> but an Ethernet splitter ?????
>>

Dmitri
03-28-08, 04:12 PM
P.Schuman wrote:

> happen to run across this thread over on the Ethernet newsgroup -

> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
> over on ebay (search RJ45 spliiter) that look like the telco 1-line
> 2-line
> adapters,

These things exist.
Here is a sample pin layout:
http://www.cabling-design.com/references/pinouts/split.shtml
Not recommended but will work on 2-pair varieties of Ethernet - 10BASE-T
and 100BASE-TX. Will not work on Gigabit Ethernet or higher though. And
no, they don't create two Ethernet network ports, they just simply create
two two-pair patch cords if you will under the sheath of a single four
wire category cable

> I could see if you were trying to split out the tip/ring (4/5) or power
> (7/8) but an Ethernet splitter ?????




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News Reader
03-28-08, 06:03 PM
Possible and advisable are two different things.

A telephone ringing signal is an 88v 20Hz A.C. signal superimposed on
48v nominal D.C. supervisory voltage.

Hardly low voltage, and not appropriate for sharing a Cat 5e cable run
with data.

Readers should observe gfretwell's caution.

Best Regards,
News Reader

lawrence.jones@siemens.com wrote:
> gfretwell@aol.com wrote:
>> Don't do this with POTS phones unless you can live with the errors
>> when the phone rings.
>
> Since 10Base-T and 100Base-TX were both designed to coexist with phone
> lines in the same cable, that shouldn't be a problem.
>
> -Larry Jones
>
> Start tying the sheets together. We'll go out the window. -- Calvin

News Reader
03-28-08, 06:09 PM
Might want to check your system clock.

Your last post came in about an hour early.

:>)

Best Regards,
News Reader

gfretwell@aol.com wrote:
> On Fri, 28 Mar 2008 16:47:40 -0400, lawrence.jones@siemens.com wrote:
>
>>> Don't do this with POTS phones unless you can live with the errors
>>> when the phone rings.
>> Since 10Base-T and 100Base-TX were both designed to coexist with phone
>> lines in the same cable, that shouldn't be a problem.
>
>
> Maybe BICSI has changed their opinion but that was what I heard when I
> was in school. I know it works but it is not recomended

gfretwell@aol.com
03-28-08, 06:51 PM
On Fri, 28 Mar 2008 16:47:40 -0400, lawrence.jones@siemens.com wrote:

>> Don't do this with POTS phones unless you can live with the errors
>> when the phone rings.
>
>Since 10Base-T and 100Base-TX were both designed to coexist with phone
>lines in the same cable, that shouldn't be a problem.


Maybe BICSI has changed their opinion but that was what I heard when I
was in school. I know it works but it is not recomended

Adair Winter
03-28-08, 07:09 PM
"P.Schuman" <pschuman_no_spam_me@interserv.com> wrote in message
> happen to run across this thread over on the Ethernet newsgroup -
>
> Some guy found a RJ45 splitter (2-RJ45 jacks to 1-RJ45 jack)
> over on ebay (search RJ45 spliiter) that look like the telco 1-line 2-line
> adapters,
> but yet this guy (and the ebay description) says these "splitters" ....
>
> Features:
> a.. Convert a single RJ45 outlet to two RJ45 sockets easily, point for
> more conveniently use
>
> b.. Increase the number of RJ45 network connections on an RJ45 outlet
>
> c.. Compact design, feel free to enjoy your internet surfing
>
> d.. Expand one RJ 45 outlet into two 8 wire RJ-45 T adapter, parallel
> wiring
>
> e.. Connector: 3 x RJ45 female
>
> f.. 100% Brand New.
>
> It doesn't even seem possible to have more "network connections"
> by just splicing more Ethernet wires together vs a dumb hub ????
>
> I could see if you were trying to split out the tip/ring (4/5) or power
> (7/8)
> but an Ethernet splitter ?????

The only way this could actually work is if you used one on both ends and
each socket was wired to use seperate pairs. Since 10/100 ethernet only
really uses 2 of the 4 pairs in a cable in theroy this would work. but again
you have to have one on each end. It will not work on gigabit ethernet.

Adair

gfretwell@aol.com
03-28-08, 08:08 PM
On Fri, 28 Mar 2008 19:09:07 -0400, News Reader <user@domain.null>
wrote:

>Might want to check your system clock.
>
>Your last post came in about an hour early.

It says 2007 eastern

gfretwell@aol.com
03-28-08, 08:09 PM
On Fri, 28 Mar 2008 19:09:07 -0400, News Reader <user@domain.null>
wrote:

>Might want to check your system clock.
>
>Your last post came in about an hour early.
>
>:>)
>
>Best Regards,
>News Reader

I turned off the DST bit, see if that helps

News Reader
03-28-08, 08:17 PM
The time indicated for your post (in the date column) says 9:08 PM,
which is offset an hour from the time you have indicated below (2007
hrs., i.e.: 8:07 PM).

Best Regards,
News Reader

gfretwell@aol.com wrote:
> On Fri, 28 Mar 2008 19:09:07 -0400, News Reader <user@domain.null>
> wrote:
>
>> Might want to check your system clock.
>>
>> Your last post came in about an hour early.
>
> It says 2007 eastern

News Reader
03-28-08, 08:19 PM
The time indicated for your post (in the date column) says 9:09 PM,
still an hour ahead.

Best Regards,
News Reader

gfretwell@aol.com wrote:
> On Fri, 28 Mar 2008 19:09:07 -0400, News Reader <user@domain.null>
> wrote:
>
>> Might want to check your system clock.
>>
>> Your last post came in about an hour early.
>>
>> :>)
>>
>> Best Regards,
>> News Reader
>
> I turned off the DST bit, see if that helps

lawrence.jones@siemens.com
03-28-08, 08:28 PM
gfretwell@aol.com wrote:
>
> Maybe BICSI has changed their opinion but that was what I heard when I
> was in school. I know it works but it is not recomended

No, it's not recommended (which I probably should have mentioned), but
it was designed to work.

-Larry Jones

It's going to be a long year. -- Calvin

lawrence.jones@siemens.com
03-28-08, 09:08 PM
News Reader <user@domain.null> wrote:
>
> Possible and advisable are two different things.

Absolutely.

> A telephone ringing signal is an 88v 20Hz A.C. signal superimposed on
> 48v nominal D.C. supervisory voltage.
>
> Hardly low voltage, and not appropriate for sharing a Cat 5e cable run
> with data.

The former is true, the latter is debatable. Cat5 cable is used for
phone wiring, so the voltage is not a problem for it (in fact, most Cat5
cable is rated for 300V). The IEEE 802.3 spec for twisted pair ethernet
requires devices to provide at least 1500V of isolation, so it's not a
problem for the attached devices, either. And the baseband signal is up
in the MHz range, so the receiver won't even see a 20Hz signal. Like I
said, twisted pair ethernet was specifically designed to coexist with
ordinary phone circuits in the same cable, although that's not
recommended for structured wiring systems.

-Larry Jones

No one can prove I did that!! -- Calvin

lawrence.jones@siemens.com
03-28-08, 09:28 PM
News Reader <user@domain.null> wrote:
>
> Your interpretation of his use of the term "parallel wiring" may be
> correct. However, it may also be that the seller has a poor
> understanding of the english language, or even the functionality of the
> product he is selling.

I suspect that both are true.

> I'm not condoning the use of splitters, I'm only suggesting that a
> legitimate product exists, that maybe the product he is selling is an
> example of the legit product, and that maybe he has represented its use
> incorrectly.

I'm sure it's some kind of legitimate product, but there aren't enough
details in the descriptions to know what the legitimate uses are!

> I'd be interested in reading the seller's e-bay description, if somebody
> wanted to post it here.

There are lots of them by a variety of sellers, although the pictures
and descriptions (in somewhat fractured English) are very similar. Here
are a couple of examples:

<http://cgi.ebay.com/CAT5-RJ45-Network-Splitter-Extender-Jointer-Plug-K25_W0QQitemZ260224301803QQihZ016QQcategoryZ67279QQssPageNameZWDVWQQrdZ1QQcmdZViewItem>
<http://cgi.ebay.com/RJ45-Splitter-1x2-Network-Ethernet-A04Connecter-adapter_W0QQitemZ230235431981QQihZ013QQcategoryZ48680QQssPageNameZWDVWQQrdZ1QQcmdZViewItem>

-Larry Jones

I've got PLENTY of common sense! I just choose to ignore it. -- Calvin

gfretwell@aol.com
03-28-08, 11:30 PM
On Fri, 28 Mar 2008 21:19:32 -0400, News Reader <user@domain.null>
wrote:

>The time indicated for your post (in the date column) says 9:09 PM,
>still an hour ahead.
>
>Best Regards,
>News Reader
>
>gfretwell@aol.com wrote:
>> On Fri, 28 Mar 2008 19:09:07 -0400, News Reader <user@domain.null>
>> wrote:
>>
>>> Might want to check your system clock.
>>>
>>> Your last post came in about an hour early.
>>>
>>> :>)
>>>
>>> Best Regards,
>>> News Reader
>>
>> I turned off the DST bit, see if that helps

I'm baffled, I only know of one clock, the one in the lower right of
the screen. I don't know why it shows up as 909 in the header

Agent said 809 on the title bar when I looked at it

DTC
03-29-08, 12:01 AM
News Reader wrote:
> A telephone ringing signal is an 88v 20Hz A.C. signal superimposed on
> 48v nominal D.C. supervisory voltage.

True

> not appropriate for sharing a Cat 5e cable run with data.

False - We have several 200 foot runs of buried CAT5 that carry
100 Meg data, digital phone TDM, analog POTS lines, and T1.

News Reader
03-29-08, 11:00 AM
The point is not whether the "cable" can withstand high voltage.

The point is that Ethernet is a low voltage, low current implementation.

The issue is induction, and induction results from current, not voltage.

If you think a high current, low frequency signal cannot impact the
receiver, you are incorrect.

If you were correct, we would not observe the minimum separation
distances from EMI sources that we do, when installing network cabling.

We keep data cabling away from AC wiring (i.e.: 60 Hz), and if we have
to cross paths with AC, we ensure that we are perpendicular to the AC
wiring, and never parallel to it, due to the effects of induction.

Best Regards,
News Reader


lawrence.jones@siemens.com wrote:
> News Reader <user@domain.null> wrote:
>> Possible and advisable are two different things.
>
> Absolutely.
>
>> A telephone ringing signal is an 88v 20Hz A.C. signal superimposed on
>> 48v nominal D.C. supervisory voltage.
>>
>> Hardly low voltage, and not appropriate for sharing a Cat 5e cable run
>> with data.
>
> The former is true, the latter is debatable. Cat5 cable is used for
> phone wiring, so the voltage is not a problem for it (in fact, most Cat5
> cable is rated for 300V). The IEEE 802.3 spec for twisted pair ethernet
> requires devices to provide at least 1500V of isolation, so it's not a
> problem for the attached devices, either. And the baseband signal is up
> in the MHz range, so the receiver won't even see a 20Hz signal. Like I
> said, twisted pair ethernet was specifically designed to coexist with
> ordinary phone circuits in the same cable, although that's not
> recommended for structured wiring systems.
>
> -Larry Jones
>
> No one can prove I did that!! -- Calvin

News Reader
03-29-08, 11:10 AM
Pretty sad when the seller can't provide enough detail (pin outs) for
you to determine what it is you are buying.

I provided a link in one of my earlier posts for a product that exists
from a reputable company (Hubbell).

Best Regards,
News Reader

lawrence.jones@siemens.com wrote:
> News Reader <user@domain.null> wrote:
>> Your interpretation of his use of the term "parallel wiring" may be
>> correct. However, it may also be that the seller has a poor
>> understanding of the english language, or even the functionality of the
>> product he is selling.
>
> I suspect that both are true.
>
>> I'm not condoning the use of splitters, I'm only suggesting that a
>> legitimate product exists, that maybe the product he is selling is an
>> example of the legit product, and that maybe he has represented its use
>> incorrectly.
>
> I'm sure it's some kind of legitimate product, but there aren't enough
> details in the descriptions to know what the legitimate uses are!
>
>> I'd be interested in reading the seller's e-bay description, if somebody
>> wanted to post it here.
>
> There are lots of them by a variety of sellers, although the pictures
> and descriptions (in somewhat fractured English) are very similar. Here
> are a couple of examples:
>
> <http://cgi.ebay.com/CAT5-RJ45-Network-Splitter-Extender-Jointer-Plug-K25_W0QQitemZ260224301803QQihZ016QQcategoryZ67279QQssPageNameZWDVWQQrdZ1QQcmdZViewItem>
> <http://cgi.ebay.com/RJ45-Splitter-1x2-Network-Ethernet-A04Connecter-adapter_W0QQitemZ230235431981QQihZ013QQcategoryZ48680QQssPageNameZWDVWQQrdZ1QQcmdZViewItem>
>
> -Larry Jones
>
> I've got PLENTY of common sense! I just choose to ignore it. -- Calvin

Robert Redelmeier
03-29-08, 01:01 PM
In comp.dcom.cabling News Reader <user@domain.null> wrote in part:
> If you think a high current, low frequency signal cannot
> impact the receiver, you are incorrect.

Well, technically ULF is seen at the receiver, but it is
too slow and neutralized by balanced signalling to make
any difference in the detection process.

> If you were correct, we would not observe the minimum
> separation distances from EMI sources that we do, when
> installing network cabling.

There are many other reasons for separation. First and foremost
is the dreaded electrical inspector who will often insist upon
it (for electrical "safety") and her word is law. Second, some
AC loads get very HF noisy (arc welders, certain motors and X-ray
machines are frequently cited) and inject high freq noise onto AC.
This noise can be troublesome.

> We keep data cabling away from AC wiring (i.e.: 60 Hz), and
> if we have to cross paths with AC, we ensure that we are
> perpendicular to the AC wiring, and never parallel to it,
> due to the effects of induction.

A clean AC draw (incandescent lighting) may produce some 60
Hz induction, but it is harmless and easily rejected by the
receiver. Similarly the telephone ring 88V, 20Hz, unless
you have an antique phone with contacts on the bell armature.
Even then the protocols are robust and will retransmit.

> Best Regards, News Reader

Please refrain from top-posting. The convention is
quote-and-respond which makes following threads and
side-comments easier.

-- Robert

News Reader
03-29-08, 01:15 PM
Robert Redelmeier wrote:
> In comp.dcom.cabling News Reader <user@domain.null> wrote in part:
>> If you think a high current, low frequency signal cannot
>> impact the receiver, you are incorrect.
>
> Well, technically ULF is seen at the receiver, but it is
> too slow and neutralized by balanced signalling to make
> any difference in the detection process.
>
>> If you were correct, we would not observe the minimum
>> separation distances from EMI sources that we do, when
>> installing network cabling.
>
> There are many other reasons for separation. First and foremost
> is the dreaded electrical inspector who will often insist upon
> it (for electrical "safety") and her word is law. Second, some
> AC loads get very HF noisy (arc welders, certain motors and X-ray
> machines are frequently cited) and inject high freq noise onto AC.
> This noise can be troublesome.
>
>> We keep data cabling away from AC wiring (i.e.: 60 Hz), and
>> if we have to cross paths with AC, we ensure that we are
>> perpendicular to the AC wiring, and never parallel to it,
>> due to the effects of induction.
>
> A clean AC draw (incandescent lighting) may produce some 60
> Hz induction, but it is harmless and easily rejected by the
> receiver. Similarly the telephone ring 88V, 20Hz, unless
> you have an antique phone with contacts on the bell armature.
> Even then the protocols are robust and will retransmit.
>
>> Best Regards, News Reader
>

I'll yield to your superior knowledge of the subject matter, and adjust
my top-posting behavior.

> Please refrain from top-posting. The convention is
> quote-and-respond which makes following threads and
> side-comments easier.
>
> -- Robert
>

Best Regards,
News Reader

glen herrmannsfeldt
03-29-08, 04:36 PM
News Reader wrote:

(snip)

> The issue is induction, and induction results from current, not voltage.

> If you think a high current, low frequency signal cannot impact the
> receiver, you are incorrect.

V=L di/dt. It depends on current and frequency. Low di/dt also
results in low inductive coupling.

> If you were correct, we would not observe the minimum separation
> distances from EMI sources that we do, when installing network cabling.

I believe ethernet can work with common mode 240VAC on the line.
(Be careful around it, though.) I was going to test it someday but
still haven't done it.

> We keep data cabling away from AC wiring (i.e.: 60 Hz), and if we have
> to cross paths with AC, we ensure that we are perpendicular to the AC
> wiring, and never parallel to it, due to the effects of induction.

Differential signaling is pretty good at keeping the signals apart.
Except for the case of arc welders (mentioned here in the past)
it is rarely a problem.

-- glen

BRMiusMAXimus
09-22-08, 03:15 PM
I thought this site might shed some light on things. It seems to use the same terminology that was talked about the thread, but in fact performs differently than one might expect.

http://www.blackbox.co.uk/solutions/pdf/90088.pdf

thanks,
Ben