What is difference betwteen SFP/GBIC (mini GBIC)

In article , wld wrote: :I have no knowlege about 1000BASE-T,LX,LH,SX etc and SFP/mini GBIC. :What these terms stand for?

The 1000 stands for a data transfer rate (including all overheads) of 1000 megabits per second.

'Base' gives you information about the media (wires of some sort)

'-T' tells you which of the several competing 1000Base implimentations has been used. You need to research the details, though, as the '-T' by itself has no meaning (it's just part of the name).

You might, for example, see 10BaseT and that is different than 10BaseTX in implimentation.

LX, LH, SX are terms used in fibre optic communications, and designate the frequency and signalling standard to be used over the fibre line.

SX is commonly used within one building between closely adjacent buildings; the 'S' hints at "short distance". There is a specific frequency of light that is used for SX, and it expects a type of fibre known as "multimode" -- which is a type of fibre that can carry several signals simultaneously [in principle] but tends to disperse the signals relatively quickly.

LX uses a different frequency, and is more suitable for longer distances. The 'L' can be read as a hint for "long distance". LX

-can- be used over multimode, but the distances you can reach that way are not particularily good. LX is usually used over a "single mode" fibre (designed for one signal at a time] that is thinner than "multimode". There are two different thicknesses of single-mode fibre that can be used with LX. My recollection is that the official distance you can reach with LX does not depend upon the fibre size... but the

*practical*, real-life, "how far can you stretch it" distance is greater with the thinner single-mode fibre. Typically you can do an entire campus with LX.

LH uses a thinner single-mode fibre. The 'LH' hints at "long haul", and it is suitable for going several tens of kilometers. LH might be used for your cross-town links to your ISP. In practice, Cisco uses a single GBIC that has the functions of both LX and LH, so you will usually see LX/LH in connection with Cisco GBICs. There -are- LX GBICs on the market that are not able to do LH, so if you need the longer distances, don't try to go with cheap third-party GBICs without testing.

There is also an SZ you might see referenced. I do not know if it has made it to an official standard yet; but it is for "super long haul", for noticably longer distances yet. SZ might be used to carry data between cities.

GBIC is the "GigaBit Interface Connector", and it is a little device that knows how to translate SX, LX, LH, etc., and or other types of gigabit signals (such as over copper), into a common format. GBIC connectors plug into slots in switches/routers, and are thus ways of changing the interface capabilities of the switches/routers without having to get new boards or replacing the switches/routers. They are, in a sense, media convertors.

(Note: some third-party GBICs are as good or better than the one's Cisco sells, for a fraction of the price of Cisco's -- but some of the brands of cheap GBICs are not very good quality or will only work well under narrow conditions.)

SFP are similar in purpose to GBIC, but are noticably smaller (and thus you can put more of them into a small space). There are not as many varieties of SFP available as there are of GBIC. 'SFP' stands for "Small Form Pluggable".

I have only a couple of minor disagreements with the response.

"BASE," in 10BASE-T for example, means "baseband." This is to differentiate these standards from 10BROAD36, a scheme for implementing Ethernet, modulated over two RF carriers, over cable TV systems. (In that case, 36 stands for the 36 MHz total channel bandwidth required for transmit and receive frequency bands, each of which requires 18 MHz.) See Clause 11 of IEEE 802.3 for all the gory details on the 10BROAD36 physical layer.

Also parenthetically, 10BROAD36 is *not* what today's cable broadband Internet services typically provide.

"T" in the various designations means "twisted pair." This originally differentiated these Ethernets from the coax variety of baseband options (10BASE2 and 10BASE5). For Gigabit Ethernet, there's also a 1000BASE-CX for very short runs of shielded twisted pair copper (25 meters), whereas

1000BASE-T is only for unshielded twisted pair cables (100 meter limit, using a 4-lane bidirectional scheme which is considerably fancier than the older 1000BASE-CX standard).

In the fiber optic variants of Ethernet, "S" I believe stands of "short wavelength," meaning 850 nm, whereas "L" stands for "long wavelength," meaning 1300 nm. And there's E for 1550 nm light.

But it's true that short wavelength often translates to shorter distances, although the fiber diameter also plays a big role in link length limits. For instance, at 10 Gb/s, 850 nm will provide link limits over some 50 um multimode fiber cables equal to 1300 nm over 62.5 um fiber cores, using a 4-lane scheme. I also agree that the short wavelength light is not used in single-mode fiber.

Anyway, these designations are not entirely consistent across the various Ethernet standards. So if things start making sense, just wait for the next standard to show up.

Bert

10BaseTX

distance

distances,

hi SY Can you access the '

' . thw web have the Knowlege GBIC/SFP ..

:)

Ryan

wld Wrote:

hi Can you access the '

' .

thw web have the Knowlege GBIC/SFP ..

:)

Ryan

wld Wrote: