Help - GbE speed and duplex

On Thu, 04 Nov 2004 16:11:52 -0600, L wrote:

> I'm back to black again :-(
>
> Are you saying:
> - data can be sent in both directions at the same time on GbE protocol, and
> - the bandwidth of GbE protocol is 2 Gbit/sec for full-duplex (sending data
> both ways at the same time) and 1 Gbit/sec for half-duplex?
>
> Thanks,
>
>
> T.

I am sorry, I am incorrect. I missed most of the GbE section in my CISCO
class, GbE now uses all 4 wire pairs (rather than just 2 as originally
designed) in a Cat5e wire or you can use Full-Duplex fiber optic (2 fibers).

GbE is a Full-Duplex protocol, but still only functions at 1Gigbit/sec.
And as 10GbE transfers at 10Gigbits/sec. (i.e. 1 or 10, respectfully,
gigs of data can be transferred per second.)

I'm am truly sorry about this mistake, and I thank you for ask because it
had me go back a read that section once more.


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Andrew Balmos (abalmos)
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On Thu, 04 Nov 2004 16:57:58 -0600, L wrote:

>
> Thank you so much for correcting it. I'm also learning daily even though I
> have been working in IT for so many years.
>
> I'm still a bit confused about the bandwith of GbE. Can GbE protocol send 1
> Gbps data to each direction **at the same time**, so we can get 2 Gbps data
> transfered (full-duplex) over the wire?
>
> Thanks,
>
> T.

No, Ethernet media (Cat5) have 4 twisted pairs in them, 10Base-T and
100Base-T use two of them and transfer at 125 Mbps. When they made GbE
they made a new media standard (Cat5e) and was able to reliably get
250Mbps out of each pair. They than used all 4 pairs to get a grand total
of 1000Mbps. So 1000Mbps of bandwidth can be used per second, thus you
have 1000Mbps for up and down combined.
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On Fri, 05 Nov 2004 00:14:50 +0100, Michael Heiming wrote:

> Nonsense again, a system has to theoretical cope with max. 2Gb/s
> on a single 1GB NIC in full-duplex mode. Which can outperform a
> standard 32bit PCI bus, you want to use 64bit slots/cards if you
> expect really heavy traffic.

I'm beging to sounds like a fool. I reread the chapter again and I mis
understood what it was saying the first time. In GbE Full-Duplex mode you
have a 1Gb/s up stream and a 1GB/s down stream.

Once again I am sorry. Thank you for the correction.

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On Thu, 04 Nov 2004 13:55:59 -0600, L wrote:

> Hi,
>
> Can some one please tell me:
>
> - does GbE mean each direction (half-duplex) can transfer 1 Gbit/sec, and
> full-duplex can transfer 2 Gbit/sec?
> - what wire speed (GByte/sec) is, and is it for half or full duplex?
>
> Thanks,
>
>
> T.

Ethernet can only send a packet one direction at a time (i.e. a packet can
not be coming to the NIC and leaving the NIC at the same time) if that
happens you have whats called a media collision in networking. So GbE
allows you to send 1 Gig of data per second, any amount of that 1 Gig can
be going either way.

Wire speed is that of how much data it can send per second. In this case 1
Gig.

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On Thu, 04 Nov 2004 14:48:11 -0600, L wrote:

> <sinp>
> Thanks.
>
> So, the definition of "wire speed" is not only for GbE. Both GbE and 10GbE
> have so called "wire speed", but they are 10 times different, correct?
>
> T.

Yes you are correct. All versions of enternet have a wire speed, and that
wire speed is the ammount of data that the wire can send per second. 10GbE
can send 10 Gigs of data a second.



--
Andrew Balmos (abalmos)
abalmos [/@t\] gmail [/dot\] _remove_this_ [/com\]

Hi,

Can some one please tell me:

- does GbE mean each direction (half-duplex) can transfer 1 Gbit/sec, and
full-duplex can transfer 2 Gbit/sec?
- what wire speed (GByte/sec) is, and is it for half or full duplex?

Thanks,


T.
--

> > - does GbE mean each direction (half-duplex) can transfer 1 Gbit/sec,
and
> > full-duplex can transfer 2 Gbit/sec?
> > - what wire speed (GByte/sec) is, and is it for half or full duplex?
> >
> > Thanks,
> >
> >
> > T.
>
> Ethernet can only send a packet one direction at a time (i.e. a packet can
> not be coming to the NIC and leaving the NIC at the same time) if that
> happens you have whats called a media collision in networking. So GbE
> allows you to send 1 Gig of data per second, any amount of that 1 Gig can
> be going either way.
>
> Wire speed is that of how much data it can send per second. In this case 1
> Gig.
>

Thanks.

So, the definition of "wire speed" is not only for GbE. Both GbE and 10GbE
have so called "wire speed", but they are 10 times different, correct?

T.
--

> --
> Andrew Balmos (abalmos)
> abalmos [/@t\] gmail [/dot\] _remove_this_ [/com\]
>
>
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"Andrew Balmos (abalmos)" <please@see.sig> wrote in message
news:pan.2004.11.04.15.26.32.400841@see.sig...

> Ethernet can only send a packet one direction at a time (i.e. a packet can
> not be coming to the NIC and leaving the NIC at the same time) if that
> happens you have whats called a media collision in networking. So GbE
> allows you to send 1 Gig of data per second, any amount of that 1 Gig can
> be going either way.
>
> Wire speed is that of how much data it can send per second. In this case 1
> Gig.

Everything said above is completely incorrect. Full-duplex ethernet has
been around for a very long time. In fact, with GigE, all connections are
full duplex (to date nobody has bothered to implement half-duplex).

DS

"David Schwartz" <davids@webmaster.com> wrote in message
news:cme5u7$iea$1@nntp.webmaster.com...
>
> "Andrew Balmos (abalmos)" <please@see.sig> wrote in message
> news:pan.2004.11.04.15.26.32.400841@see.sig...
>
> > Ethernet can only send a packet one direction at a time (i.e. a packet
can
> > not be coming to the NIC and leaving the NIC at the same time) if that
> > happens you have whats called a media collision in networking. So GbE
> > allows you to send 1 Gig of data per second, any amount of that 1 Gig
can
> > be going either way.
> >
> > Wire speed is that of how much data it can send per second. In this case
1
> > Gig.
>
> Everything said above is completely incorrect. Full-duplex ethernet
has
> been around for a very long time. In fact, with GigE, all connections are
> full duplex (to date nobody has bothered to implement half-duplex).
>

I'm back to black again :-(

Are you saying:
- data can be sent in both directions at the same time on GbE protocol, and
- the bandwidth of GbE protocol is 2 Gbit/sec for full-duplex (sending data
both ways at the same time) and 1 Gbit/sec for half-duplex?

Thanks,


T.
--

In comp.os.linux.networking "Andrew Balmos (abalmos)" <please@see.sig>:
> On Thu, 04 Nov 2004 13:55:59 -0600, L wrote:

>> Hi,
>>
>> Can some one please tell me:
>>
>> - does GbE mean each direction (half-duplex) can transfer 1 Gbit/sec, and

Is there half-duplex for GB?

>> full-duplex can transfer 2 Gbit/sec?

Theoretical, you probably want disks that can cope with
read/write at that speed.

>> - what wire speed (GByte/sec) is, and is it for half or full duplex?

> Ethernet can only send a packet one direction at a time (i.e. a packet can
> not be coming to the NIC and leaving the NIC at the same time) if that
> happens you have whats called a media collision in networking. So GbE

You should seriously think about upgrading your LAN equipment to
this century, full-duplex is more or less standard, allowing to
send/receive at the same time.

--
Michael Heiming (X-PGP-Sig > GPG-Key ID: EDD27B94)
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