Re: Packet delivery on a Ethernet Wire

So if 1G 1000BASE-T, pairs are bidirectional, full duplex, does that mean
each singe wire in the pair group is doing either transmit or recieve. In
that case I can understand there will be no collision, as each single wire
will be either transmitting or receiving.

But if a single wire in the pair group is doing both transmitting and
receiving, you have frames going in both directions on a single wire. Its
like cars coming in both directions in a single lane. In this case you will
expect collisions.

Please can someone clarify .....

On 1G 1000BASE-T, pairs are bidirectional, full duplex.
(Like your POTS phone line, you can talk while you listen)
No collisions.

On Sun, Jul 31, 2011 at 9:47 PM, Joe Astorino <joeastorino1982_at_gmail.com>wrote:

> If all 4 pairs are used in 1000Base-T I wonder how POE also rolls into
> that...
>
>
> On Sun, Jul 31, 2011 at 1:55 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:
>
>> On 1G 1000BASE-T, pairs are bidirectional, full duplex.
>> (Like your POTS phone line, you can talk while you listen)
>> No collisions.
>> Signal treatment is beyong my current understanding, but it uses 5 levels
>> in each pair!
>> Amazing...
>>
>>
>> Irfan Sid @ 31/07/2011 11:32 -0300 dixit:
>>
>>>
>>> On 1 Gig link pin 4,5, 7 and 8 are bi-directional meaning the same wire
>>> will be used for Tx and Rx?
>>> And for 10/100 those pins are not used at all, so 10/100 is serial
>>> rather then parrallel.
>>> Does that mean that odd collison is possible on both since they are
>>> bidirectional packet streams??
>>>
>>>
>>> http://pinouts.ws/rj-45-**pinout.html<http://pinouts.ws/rj-45-pinout.html>
>>>
>>>
>>> http://pinouts.ru/Net/**Ethernet10BaseT_pinout.shtml<http://pinouts.ru/Net/Ethernet10BaseT_pinout.shtml>
>>>
>>>
>>>
>>>
>>> On Sun, Jul 31, 2011 at 2:50 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar<mailto:
>>> tron_at_huapi.ba.ar>> wrote:
>>>
>>> I stand corrected, in 1000BASE-T there are 4 bidirectional signal
>>> paths,
>>> so it's basically a parallel interface.
>>>
>>> Sorry about that.
>>> -Carlos
>>>
>>> Aaron Riemer @ 31/07/2011 05:36 -0300 dixit:
>>>
>>> Yep. However just doing some reading it looks like Gigabit copper
>>> (1000BaseT) uses all four pairs and this link seems to suggest
>>> that data is
>>> sent in parallel.
>>> http://www.cisco.com/en/US/__**tech/tk389/tk214/tech___**
>>> digest09186a0080091a86.html<http://www.cisco.com/en/US/__tech/tk389/tk214/tech___digest09186a0080091a86.html>
>>> <http://www.cisco.com/en/US/**tech/tk389/tk214/tech_**
>>> digest09186a0080091a86.html<http://www.cisco.com/en/US/tech/tk389/tk214/tech_digest09186a0080091a86.html>
>>> >
>>>
>>> "1000BASE-T works by using all four of the Category 5 pairs to
>>> achieve 1000
>>> Mbps operation over the installed Category 5 copper cabling.
>>> 1000 Mbps data
>>> rates are achieved by sending and receiving a 250 Mbps data
>>> stream over each
>>> of the four pairs simultaneously (4 X 250 Mbps = 1 Gbps)."
>>>
>>>
>>>
>>> Cheers,
>>>
>>> -Aaron.
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: nobody_at_groupstudy.com <mailto:nobody_at_groupstudy.com>
>>> [mailto:nobody_at_groupstudy.com <mailto:nobody_at_groupstudy.com>**]
>>> On
>>>
>>> Behalf Of
>>> Irfan Sid
>>> Sent: Sunday, 31 July 2011 1:02 PM
>>> To: Aaron Riemer
>>> Cc: Carlos G Mendioroz; Cisco certification; Cisco certification
>>> Subject: Re: Packet delivery on a Ethernet Wire
>>>
>>> So does that mean that in copper wire, you have two paths ie
>>> full duplex,
>>> one for transmit and one for recieve. One pair of the copper will
>>> be
>>> dedicated to tansmit and one to recieve. Each path transmitting
>>> serially.
>>>
>>> On Fibre its the same, you have two fibre's one for transmit and
>>> one for
>>> receive and data is transmitted serially on them.
>>>
>>> Is this correct?
>>>
>>> On Thu, Jul 28, 2011 at 6:07 AM, Aaron Riemer
>>> <ariemer_at_amnet.net.au <mailto:ariemer_at_amnet.net.au>> wrote:
>>>
>>> My apologies. I must have misread.
>>>
>>> http://en.wikipedia.org/wiki/_**_Data_transmission<http://en.wikipedia.org/wiki/__Data_transmission>
>>> <http://en.wikipedia.org/wiki/**Data_transmission<http://en.wikipedia.org/wiki/Data_transmission>
>>> >
>>>
>>> Thanks for clearing that up.
>>>
>>> Cheers,
>>>
>>> -Aaron.
>>>
>>> -----Original Message-----
>>> From: nobody_at_groupstudy.com <mailto:nobody_at_groupstudy.com>
>>> [mailto:nobody_at_groupstudy.com
>>>
>>> <mailto:nobody_at_groupstudy.com>**] On Behalf Of
>>> Carlos G Mendioroz
>>> Sent: Thursday, 28 July 2011 12:27 AM
>>> To: Aaron Riemer
>>> Cc: 'Irfan Sid'; 'Cisco certification'; 'Cisco certification'
>>> Subject: Re: Packet delivery on a Ethernet Wire
>>>
>>> Aaron,
>>> copper has "pairs" because you use one wire as a reference
>>> to the other.
>>> But there is only one signal path (each way), and it works
>>> serially.
>>> -Carlos
>>>
>>> Aaron Riemer @ 27/7/2011 4:09 -0300 dixit:
>>>
>>> Hi Irfan,
>>>
>>> I believe with copper Ethernet (100BaseTX for example)
>>> since there are
>>> copper "pairs" the data is sent in parallel. I would
>>> assume the only way
>>> parallel data transmission would work with fibre is if a
>>> different band
>>>
>>> of
>>>
>>> light is used (CWDM for example).
>>>
>>> Queuing on the router/switch only affects packets within
>>> the router
>>>
>>> itself
>>>
>>> and has no bearing on packets along the wire (unless
>>> they are dropped).
>>>
>>> Tools such as compression / LFI / DSCP marking are
>>> examples of the
>>>
>>> router
>>>
>>> manipulating the packets in some way before transmission
>>> out an
>>>
>>> interface.
>>>
>>> Cheers,
>>>
>>> -Aaron.
>>>
>>>
>>> -----Original Message-----
>>> From: nobody_at_groupstudy.com
>>> <mailto:nobody_at_groupstudy.com>
>>> [mailto:nobody_at_groupstudy.com
>>>
>>> <mailto:nobody_at_groupstudy.com>**] On Behalf Of
>>> Irfan Sid
>>> Sent: Wednesday, 27 July 2011 1:48 PM
>>> To: Cisco certification; Cisco certification
>>> Subject: Packet delivery on a Ethernet Wire
>>>
>>> This maybe a stupid question would appreciate if someone
>>> can clearify:
>>>
>>> Are Ethernet packets delivered serially on the physcial
>>> medium ie copper
>>>
>>> or
>>>
>>> fibre - one after another in one single file or line if
>>> you will. Or are
>>> they delivered in parallel ie. two or more packets can be
>>> in
>>>
>>> transmission
>>>
>>> along each other in parallel.
>>>
>>> Also when you enable queueing on Router/switch. Does
>>> this only effect
>>>
>>> the
>>>
>>> behaviour of how the router treats the packet on the
>>> inbound or outbound
>>> interface or does it also effect the behaviour of the
>>> packet when it is
>>> actually in transit on the wire itself.
>>>
>>>
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>>> --
>>> Carlos G Mendioroz <tron_at_huapi.ba.ar
>>> <mailto:tron_at_huapi.ba.ar>> LW7 EQI Argentina
>>>
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>>>
>>>
>>> -- Carlos G Mendioroz <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar
>>> >>
>>> LW7 EQI Argentina
>>>
>>>
>>>
>> --
>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>
>>
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>
>
> --
> Regards,
>
> Joe Astorino
> CCIE #24347
> Blog: http://astorinonetworks.com
>
> "He not busy being born is busy dying" - Dylan

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Received on Mon Aug 01 2011 - 10:02:24 ART