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1 Gbps LAN Card - Speed

I have 1 Gbps LAN Card. My query is does the LAN card supports 1Gbps Rx & I Gbps TX at the same time or it support 1 Gbps combined for RX & TX
1 Solution
(GbE or 1 GigE) is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second, as defined by the IEEE 802.3-2008 standard. Half-duplex gigabit links connected through hubs are allowed by the specification but in the marketplace full-duplex with switches are normal.
SrikantRajeevAuthor Commented:
This is not the answer i am looking for.
I am using 1 Gbps in Full duplex mode.
WIll i get 1 Gbps RX & 1 Gbps thorughput or it will be the combination of 1Gbps for both RX & TX
Technically you could get 1 GIG up and one GIG down at the same time, per the spec. The signaling rate permits 1 GBPS in and out, and there is a seperate physical link for each. Using real world cabling and protocols you will be hard pressed to ever see more than 800Mbps under the best of conditions, and I suppose if you use lower quality cabling and longer lengths input and output could slightly interfere at higher bandwidths.

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Full-duplex Ethernet connections work by making simultaneous use of two physical pairs of twisted cable (which are inside the jacket), wherein one pair is used for receiving packets and one pair is used for sending packets (two pairs per direction for some types of Ethernet), to a directly-connected device. This effectively makes the cable itself a collision-free environment and doubles the maximum data capacity that can be supported by the connection.
So it's a combination of;
Ref: http://en.wikipedia.org/wiki/Duplex_(telecommunications)#Full-duplex
depends on your card switch and cable
If it says Gigabit Full Duplex in the specs and if you're connected to a network device that is also Gigabit Full Duplex (note that most ALL gigabit devices are half duplex) AND if you are using high quality Cat6 cabling between the two, then yes you should be able to get 1Gb TX and 1GB RX.

Any change in the factors I listed above and performance will decrease.
Gigabit Ethernet uses all four wire pairs simultaneously.  If you don't have all four pairs (8 wires) terminated properly, you will never make a link.

angel_fire2701's comment only applies to 10BASE-T and 100BASE-T, where transmit is on pins 1&2, receive is on 3&6.

1000BASE-T is bidirectional on all pairs.

In theory, 1000BASE-T would = 1000Mbps = 125MB/sec.  No hard drive would be able to sustain this speed, so you'd be looking at server-to-server or to a storage array.

Even with this, you have packet loss, latency, and overhead from the operating system.  Windows takes a lot of overhead to generate TCP/IP packets, so you'll never approach maximum speed without something like a TCP offload engine...a processor dedicated to generating your packets.

TCP also utilizes error checking and re-transmits.  So, a percentage of your packets (hopefully a small percentage) will not contain any new data...just resending data for which it did not receive an acknowledgment.

As an example, I transferred a 9.3GB file between two servers with single GbE NICs.  The receiving server had 4x10K rpm SCSI RAID10.  The sending server was 6x7.2K rpm SATA-1.5 in RAID6.

It ranged between 82-90 MB/sec.  Finished in about 2 minutes.  Not bad, considering the theoretical limit is 125MB/sec.

Potential bottlenecks: overhead, disk read speed, disk write speed, cache size.

Both NICs were plugged into the same switch stack, which has plenty of capacity.  But if you are hopping to more switches and/or traversing a router, you have additional latency to contend with.
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