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TRANSMIT CHARACTERISTIC OF 1000BASE-SX SFP

These items is described on ITU-T standard : 802.3-2005

UNDERSTANDING LAUNCHED OPTICAL POWER WITHOUT INPUT TO TRANSMITTER

This is term that is used in Passive Optical Network Technology (PON). PON devices consist of : OLT and ONU/ONU. Downstream is direction from OLT to ONU/ONT, while upstream is direction from ONU/ONT to OLT.

Launched optical power without input to transmitter is different from mean launched optical power.

The mean launched power at OLT and ONU/ONT is the average power of a pseudo-random data sequence coupled into the fibre by the transmitter. It is given as a range to allow for some cost optimization and to cover all allowances for operation under standard operating conditions, transmitter connector degradation, measurement tolerances, and ageing effects.

In operating state, the lower figure is the minimum power which shall be provided and the higher one is the power which shall never be exceeded.

NOTE - The measurement of the launched power at the ONU/ONT optical interface shall take into account the bursty nature of the upstream traffic transmitted by the ONU/ONT.

In the upstream direction, the ONU transmitter shall launch no power into the fibre in all slots which are not assigned to that ONU. The ONU shall also launch no power during the Guard time of slots that are assigned to it, with the exception of the last Tx Enable bits which may be used for laser pre bias, and the Tx Disable bits immediately following the assigned cell, during which the output falls to zero. The launched power level during laser pre-bias must be less than 0.1 of the one level.

www.mblast.com/files/companies/89960/Document/gpon_pmd_white_v01.doc

Optical Power Bidget Calculation

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Solution

Optical power budget is term used to describe total amount of light energy amplitude available over a certain link path. The budget can be determined by subtracting the Receiver Sensitivity from the Optical Output Power. The optical budget serves as a useful estimation to determine if sufficient optical output power remains on the receiver side of an optical link. The optical power budget also refers to the allocation of available optical power (transmitted into a given fiber by a given source) among various loss-producing mechanisms.

The loss is caused by various factors. Typical losses are caused by fiber attenuation (per km), slice attenuation (per slice), and connector attenuation (per connector pair).

[Suggestions]

1. Power Budget = (Output / Launch Power) - (Receiver Sensitivity)
2. Worse case Optical Power Budget = (Min TX power) - (Max RX sensitivity) - (LED aging factor) - (insertion loss)

We'll use the following values to illustrate:
Min Tx Power = -9.5 dBm
Max Rx Sensitivity = -20 dBm
Estimated LED aging = 1 dB
Estimated Insertion loss = 1 dB

3. Therefore:
Optical Power Budget = (-9.5 dBm) - (-20 dBm)
Maximum Allowable Loss = 10.5 dB

4. Worst case OPB = Power Budget - Total Optical Power Loss =>
10.5 dB - 1dB (for LED aging) - 1dB (for insertion loss) - 1 dB (for per connector pair) - 2dB (safety factor) = 5 dB

5. Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

The Optical Power Budget is based on a theoretical calculation, and is for reference only. We still strongly recommend that you perform on-site testing to verify the result. On the data sheet, the supported fiber transmission distances are stated on each switch, with fiber port orSFP fiber modules. The customer can select the desired model without performing the power budget calculation.

http://www.moxa.com/support/faq/faq_detail.aspx?f_id=1239

Optical Power Bidget Calculation

Location: Home >> Support >> Technical FAQs >> Question 1239

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Technical FAQs

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Question	How do I calculate the Optical Power Budget?
Question Type	Application
Updated	Feb 27,2008
Hits	797
Products	SFP-1G Series, EDS-510A Series, EDS-726 Series, EDS-518A Series, EDS-516A Series, EDS-505A/508A Series, EDS-405A/408A Series, EDS-316 Series, EDS-309 Series, EDS-P308 Series, EDS-305-M12 Series, EDS-305/308 Series, EDS-205/208 Series, ED6008, EDS-405, EDS-50/505, OS5008, EDS-728 Series, PT-7

Solution

Optical power budget is term used to describe total amount of light energy amplitude available over a certain link path. The budget can be determined by subtracting the Receiver Sensitivity from the Optical Output Power. The optical budget serves as a useful estimation to determine if sufficient optical output power remains on the receiver side of an optical link. The optical power budget also refers to the allocation of available optical power (transmitted into a given fiber by a given source) among various loss-producing mechanisms.

The loss is caused by various factors. Typical losses are caused by fiber attenuation (per km), slice attenuation (per slice), and connector attenuation (per connector pair).

[Suggestions]

1. Power Budget = (Output / Launch Power) - (Receiver Sensitivity)
2. Worse case Optical Power Budget = (Min TX power) - (Max RX sensitivity) - (LED aging factor) - (insertion loss)

We'll use the following values to illustrate:
Min Tx Power = -9.5 dBm
Max Rx Sensitivity = -20 dBm
Estimated LED aging = 1 dB
Estimated Insertion loss = 1 dB

3. Therefore:
Optical Power Budget = (-9.5 dBm) - (-20 dBm)
Maximum Allowable Loss = 10.5 dB

4. Worst case OPB = Power Budget - Total Optical Power Loss =>
10.5 dB - 1dB (for LED aging) - 1dB (for insertion loss) - 1 dB (for per connector pair) - 2dB (safety factor) = 5 dB

5. Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

The Optical Power Budget is based on a theoretical calculation, and is for reference only. We still strongly recommend that you perform on-site testing to verify the result. On the data sheet, the supported fiber transmission distances are stated on each switch, with fiber port orSFP fiber modules. The customer can select the desired model without performing the power budget calculation.

Mengenal G.SHDSL

Type of standard for DSL* capable of speeds of 2.3mbps, or up to 4.6mbps in some cases, for both upload and download speeds. (1)

G.SHDL is the acronym of Giga Single-pair High bit rate Digital Subscriber Line (2)

G.SHDSL is a new international standard for single-pair, high-speed DSL, as defined in the ITU-T Standard G.991.2. Unlike asymmetric DSL, which was designed for residential applications in which more bandwidth is delivered downstream (to the house) than is available upstream (to the Internet), G.SHDSL is symmetrical - offering 2.3M bit/sec in both directions.

This makes G.SHDSL better-suited for business applications, which require higher-speed bandwidth in both directions.

G.SHDSL combines the positive aspects of existing copper-based, high-speed communications with the benefits of increased data rates, longer reach and less noise.

*DSL = Digital line subscriber


(1) http://www.computerhope.com/jargon/g/gshdsl.htm
(2) http://www.acronymdb.com/acronym/G.SHDSL

MLM dan SLM

Kalau multimode dan singlemode adalah pembagian jenis kabel fiber optik, MLM dan SLM adalah jenis spektrum sinyal optik yang dipancarkan.

MLM = Multi longitudinal mode
SLM = Singe longitudinal mode

Figure 1 - MLM Laser Spectral Output

Figure 2 - SLM Laser Spectral Output

Multi-mode and Single-mode optical fiber

There are two general categories of optical fiber: single-mode and multimode


Figure 2. Single-Mode and Multimode Fibers


Multi-mode optical fiber (multimode fiber or MM fiber or fibre) is a type of optical fiber mostly used for communication over shorter distances, such as within a building or on a campus. Typical multimode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters—more than sufficient for the majority of premises applications.

Multimode fiber was the first type of fiber to be commercialized. It has a much larger core than single-mode fiber, allowing hundreds of modes of light to propagate through the fiber simultaneously. Additionally, the larger core diameter of multimode fiber facilitates the use of lower-cost optical transmitters (such as light emitting diodes [LEDs] or vertical cavity surface emitting lasers [VCSELs]) and connectors.

Single-mode fiber, on the other hand, has a much smaller core that allows only one mode of light at a time to propagate through the core. While it might appear that multimode fibers have higher capacity, in fact the opposite is true. Singlemode fibers are designed to maintain spatial and spectral integrity of each optical signal over longer distances, allowing more information to be transmitted.

Its tremendous information-carrying capacity and low intrinsic loss have made single-mode fiber the ideal transmission medium for a multitude of applications. Single-mode fiber is typically used for longer-distance and higher-bandwidth applications (see Figure 3). Multimode fiber is used primarily in systems with short transmission distances (under 2 km), such as premises communications, private data networks, and parallel optic applications.

While fiber optic cable itself has become cheaper over time - a equivalent length of copper cable cost less per foot but not in capacity. Fiber optic cable connectors and the equipment needed to install them are still more expensive than their copper counterparts.

Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

Single Modem fiber is used in many applications where data is sent at multi-frequency (WDM Wave-Division-Multiplexing) so only one cable is needed - (single-mode on one single fiber)

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type.

Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm.

jump to single mode fiber page

Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron range for the light carry component (in the US the most common size is 62.5um). Most applications in which Multi-mode fiber is used, 2 fibers are used (WDM is not normally used on multi-mode fiber). POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fiber gives you high bandwidth at high speeds (10 to 100MBS - Gigabit to 275m to 2km) over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission so designers now call for single mode fiber in new applications using Gigabit and beyond.

The use of fiber-optics was generally not available until 1970 when Corning Glass Works was able to produce a fiber with a loss of 20 dB/km. It was recognized that optical fiber would be feasible for telecommunication transmission only if glass could be developed so pure that attenuation would be 20dB/km or less. That is, 1% of the light would remain after traveling 1 km. Today's optical fiber attenuation ranges from 0.5dB/km to 1000dB/km depending on the optical fiber used. Attenuation limits are based on intended application.

sumber :

http://www.iec.org/online/tutorials/fiber_optic/topic02.asp

http://en.wikipedia.org/wiki/Multi-mode_fiber

http://www.arcelect.com/fibercable.htm

IP Multicast to MAC Address Mapping

Map Multicast MAC address to IP Multicast Addresses

In the course of reading through the BSCI authorize self-study guide, I’ve come across a multicast example where the author talks about the concepts behind the multicast IP to MAC address mapping.

• In order to achieve the translation between a Layer 3 IP multicast address and Layer 2 multicast MAC address, the low-order 23 bits of the IP address (Layer 3) is mapped into the low-order 23 bits of the MAC address (Layer 2).
• The high order 4 bits of the Layer 3 IP address is fixed to 1110 to indicate the Class D address space between 224.0.0.0 through 239.255.255.255
  • Ethernet MAC addresses start with 01:00:5E, allowing for a range from 01:00:5E:00:00:00 through 01:00:5E:7F:FF:FF.
• With 32 total bits present in an IP address and 4 high order bits of it set at 1110, we are left with 28 bits of unique IP addresses we can use (32 - 4 = 28).
• But remember, 23 low-order bits out of the 28 available bits are mapped to the MAC address, giving us 5 remaining bits of overlap.
• With the 5 bits of extra overlap, there are 32 (2⁵ = 32) IP multicast address that map to one MAC multicast address.

The problem is, the book does not explain or show how it solved the mapping. So I went about researching how it was done. If you happened to be studying for BSCI, I am referring to the section of the BSCI: Authorized Self-Study Guide, by Teare and Paquet, that starts on page 598 - 600.

The following is an example of how we arrive with those 32 IP addresses that map to a single MAC address:

For reference, use the following conversion chart for converting hex to binary and vice versa

Let’s start by using the example MAC address given in the book :

01:00:5e:0a:00:01

1. Convert the hexadecimal MAC address 01:00:5e:0a:00:01 to binary
   • 0000 0001 : 0000 0000 : 0101 1110 : 0000 1010 : 0000 0000 : 0000 001
   • Here’s a breakdown of the conversion bit by bit:
     
2. Isolate the 23 low-order binary bits from the converted MAC address:
   • 0000 0001 : 0000 0000 : 0101 1110 : 0000 1010 : 0000 0000 : 0000 0001
3. Take the low order 23 bits from step 2 and plug it into the low-order 23 bits of the IP address (do this in binary):
   • 1110 xxxx : x000 1010 : 0000 0000 : 0000 0000
     • 1110 - First 4 high-order bits of the IP address for the multicast address space (224.x.x.x).
     • xxxx x - 5 remaining bits after the 23bits of the IP address is mapped to the MAC address plus the 4 high order bits 1110. This is equal to 32 total IP addresses.
4. Convert the binary equivalent of the IP addresses to decimal, replacing the x variables with all the values to get all 32 possible IP addresses:
   • 1110 0000 : 0000 1010 : 0000 0000 : 0000 0001 = 224.10.0.1
   • 1110 0001 : 0000 1010 : 0000 0000 : 0000 0001 = 225.10.0.1
   • 1110 0010 : 0000 1010 : 0000 0000 : 0000 0001 = 226.10.0.1
   • 1110 0011 : 0000 1010 : 0000 0000 : 0000 0001 = 227.10.0.1
   • 1110 0100 : 0000 1010 : 0000 0000 : 0000 0001 = 228.10.0.1
   • 1110 0101 : 0000 1010 : 0000 0000 : 0000 0001 = 229.10.0.1
   • 1110 0110 : 0000 1010 : 0000 0000 : 0000 0001 = 230.10.0.1
   • 1110 0111 : 0000 1010 : 0000 0000 : 0000 0001 = 231.10.0.1
   • 1110 1000 : 0000 1010 : 0000 0000 : 0000 0001 = 232.10.0.1
   • 1110 1001 : 0000 1010 : 0000 0000 : 0000 0001 = 233.10.0.1
   • 1110 1010 : 0000 1010 : 0000 0000 : 0000 0001 = 234.10.0.1
   • 1110 1011 : 0000 1010 : 0000 0000 : 0000 0001 = 235.10.0.1
   • 1110 1100 : 0000 1010 : 0000 0000 : 0000 0001 = 236.10.0.1
   • 1110 1101 : 0000 1010 : 0000 0000 : 0000 0001 = 237.10.0.1
   • 1110 1110 : 0000 1010 : 0000 0000 : 0000 0001 = 238.10.0.1
   • 1110 1111 : 0000 1010 : 0000 0000 : 0000 0001 = 239.10.0.1
   • 1110 0000 : 1000 1010 : 0000 0000 : 0000 0001 = 224.10.0.1
   • 1110 0001 : 1000 1010 : 0000 0000 : 0000 0001 = 225.138.0.1
   • 1110 0010 : 1000 1010 : 0000 0000 : 0000 0001 = 226.138.0.1
   • 1110 0011 : 1000 1010 : 0000 0000 : 0000 0001 = 227.138.0.1
   • 1110 0100 : 1000 1010 : 0000 0000 : 0000 0001 = 228.138.0.1
   • 1110 0101 : 1000 1010 : 0000 0000 : 0000 0001 = 229.138.0.1
   • 1110 0110 : 1000 1010 : 0000 0000 : 0000 0001 = 230.138.0.1
   • 1110 0111 : 1000 1010 : 0000 0000 : 0000 0001 = 231.138.0.1
   • 1110 1000 : 1000 1010 : 0000 0000 : 0000 0001 = 232.138.0.1
   • 1110 1001 : 1000 1010 : 0000 0000 : 0000 0001 = 233.138.0.1
   • 1110 1010 : 1000 1010 : 0000 0000 : 0000 0001 = 234.138.0.1
   • 1110 1011 : 1000 1010 : 0000 0000 : 0000 0001 = 235.138.0.1
   • 1110 1100 : 1000 1010 : 0000 0000 : 0000 0001 = 236.138.0.1
   • 1110 1101 : 1000 1010 : 0000 0000 : 0000 0001 = 237.138.0.1
   • 1110 1110 : 1000 1010 : 0000 0000 : 0000 0001 = 238.138.0.1
   • 1110 1111 : 1000 1010 : 0000 0000 : 0000 0001 = 239.138.0.1
5. All the 32 IP addresses on step 4 map to MAC address 01:00:5e:0a:00:01

Convert IP Multicast Address to Multicast MAC Address

Conversely, a multicast IP address can be converted to its equivalent MAC address. Once you’ve figured out how to convert from Layer 2 MAC to Layer 3 IP, doing the reverse is easy.

To start, we can pick any address from the 32 IP addresses we converted above. Let’s pick a random one like 227.138.0.1

1. First convert the address 227.138.0.1 to binary:
   • 11100011 : 10001010 : 00000000 : 00000001
   • We’re only concerned with the red colored portion which represents the low-order 23bits of the IP address.
     
   • Notice that we are dropping the high order bit of the second octet.
     
2. Convert those 23 bits to hexadecimal:
   • 0A:00:01
3. We already know that the first 3-bytes (24 bits) of the MAC address is 01:00:5E. This was established earlier in the article. Simply append the result on step 2 to the first 3-bytes and you have your MAC address:
   • 01:00:5E:0A:00:01
   • *You can pick any of the 32 Ip addresses we have on the list above and you will always get 01:00:5E:0A:00:01 as your MAC address following the steps just mentioned.

To summarize:

• 1^st octet - Notice that the first octet is left alone.
• 2^nd octet - You only need to convert the last 7 bits to hex. The second octet in decimal is 138. But if you drop the highest order bit, it becomes a decimal 10 or hex 0A.
• 3^rd octet - Convert it directly to hex.
• 4^th octet - Convert it directly to hex.

taken from : http://routemyworld.com/2009/03/04/ip-multicast-to-mac-address-mapping/

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