The objective of this article is meant to be for someone who has not done Optical Networking or Optical Engineering and this is why we put together this article from today's Conference
23 September 2016 15.00Hrs G.M.T
Let get started by asking this question. how many of us reading this article have deployed Optical links or engineered one or have designed optical networks or let re-phrase like this, how many of us have designed or engineered an optical transmission link( SDH/WDM)? or a multiple-node optical transport network? ok! like we said this article was designed for someone who have fairly or no prior knowledge of Optical Networking.
We here you say hmmmm. ok not to worry. now we speak from the provider side or provider services, how many of us are considering to lease a wavelength or multiple wavelengths in the next 6-12 months for providing connectivity? one, two ok Thank! you.
Now in reference to this article with a focus on dark fibre or sometimes called in outer regions as grey fibre. How many of you are considering to lease a dark fibre or wavelength services in upcoming months?, Ok excellent! so ok assuming we have our audience reading this article coming from IP networking background and we will just have to level set for those of you who have not been dealing with optical networking.Most of the time if you are dealing with data networking, the router, MPLS switches, layer 2 and above, usually what you see is a grey cloud, you have the edge device CE, you have the core (P) and the edge core demarcation.(PE).
Typically, this can be across countries so you don't necessarily have to care about the underlying physical infrastructure. All we care about is the logical connectivity between the routers and switches. One often needs to know if the routers have a 10g, 40g, 100gig interfaces and how many of this interfaces are available.But depending on applications obviously, you do care sometimes. This is what we see in textbooks from juniper or Cisco.
For optical networking, however, the physical actual fibre map is an important element for optical link or optical network engineering . So what we see and important in any optical networking design is that we always need to know, how the actual underlying topology is being connected;the fibre distance and fibre characteristics to design an optical networks assuming you are planning for an optical networks, optical links, where there is a ring type topology, where there is a mesh type topology, where there is a point-to-point or point to multi-point. topology. these is always an important consideration.
In optical transmission layer, one needs to know exactly the underlying fibre topology, the fibre details and characteristics so that the optical layer and equipment can be dimensioned accordingly.
So let walk through on how an optical network and link can be designed.
In this article, we will look at this from the physics and physical engineering point of view and also from a networking point-of view so that we can see a bigger picture.
A little bit about our background as well, We are fortunate to and have an opportunity to design all networks in this field for the Tier-1's Whether is in the US, North America, Asia Pacific and now Africa.
Let start from the basics which is a point-to-point and answer some common questions for any optical link/network planning. Since we are dealing with fibre optical networks, the condition of the fibre, the length of the fibre, the characteristics of the fibre are very important information before you start designing any optical engineering network of links. For example, the length, obviously you need to know the distance, is it going to be from rack to rack within a data centre.Is it going to be from data centre to data centre e.g TI tO T2 or E1 TO E2,. i.e the fibre distance or fibre topology map for the design or is it going to be from city to city.
Secondly, how many fibre strands do you have? from the extreme case running to vendors of service provider. The only lease or by-fibre is one strand at a time. We mean not fibre pair but one and they want you to do high capacity transmission over a single fibre stand. A low cost provider will like to do that where the business case justifies it. Do you also get a multiple fibre strands sometimes in cases of North America where the providers are so fibre rich. You have multiple fibre in that case you might not need WDM.Right! because each fibre pair can actually be put 10gig capacity, 100 gig capacity and that might be enough where dark fibre is so cheap or so abundant between some locations, countries or some cities.
So after you have understand the connectivity from this point to that point. How many fibre can you get, lease, rent, borrow?
Thirdly is the type of fibre string. Obviously, if you talk about metro, regional or long haul meaning spanning a hundred or thousand of kilometres.In all the cases, it is likely to be single-mode fibre.This is the type of fibre used for long distance transmision whereas multi-mode fibre is more like cross shelf between rack types. Also there are multiple fibre types as well(SMF). standard common fibre (SMF) types are G652 (SMF-28) G653(DSF) G655(NZDSF). In japan, there are some fibres using G653 which are quite very challenging in the way you design that link.There are some techniques which you can use with seebeck equipment over DSF fibre depending on the distance and the condition of the fibre
e.g coning'S SMF-28 is commonly used in todays networks.
Fourthly, the condition of the fibre strand meaning do the strands have a lot of knots in it, connections, a lot of space, air space due to eigen or microbend factor. This affect the overall loss between point A to point B. Why do we care about high loss fibre? This is because the loss is directly proportional to amplifier in the link ie. amplifiers might be required if the fibre loss is very high therefore you will have to buy more equipment to transmit from point A to Point B if the loss is too high. Also the age of the fibre. is it underground or area fibre. These are all very important as it poses varying challenges because the design for a fibre in japan is different from India and Illinois, Chicago. Also germane is the number of splices or connections on the fibre.
Lastly, is your expectation on the bandwidth that you will transport over this fibre link meaning the End of Life (EOL)transmission capacity. This answers the question, how big should "the pipe" be? Do you need 10Gb/s? 40Gb/s or 100 Gb/s or multiple 100Gb/s per wavelength. How many wavelength(s) or "highway lanes" do you need. The End of Life means the life cycle of the network. what is your expectation? right!depending on the capacity you need. Vendors like NGT or whoever will have to design the network accordingly by picking different level blocks to put together the design for you. You want an optimized for the first course, that one approach or optimize for flexibility, that another approach .
For us we deal with the spectrum of customers to the single fibre strand.
The Only one may be HL of 10Gig or NGT want 96 channel 100gig? they won. No questions to ask. we know how to use the capacity. we know that we will grow with that, infact you have to tell us if this platform can upgrade to 200 per wavelength as well. so we have a whole spectrum of requirement. This is very important.
Today as at the writing of this article, we can clearly inform you that terabit link capacity is not uncommon to connect data centres in metro networks e,g in tokyo, japan , hong kong etc. Customers directly buy say give us 500gig between these two point or give us 600gig between theses two points.Very very not uncommon, in order words it very common especially in the datacentre interconnections (DCI)
One of the key thing about fibre is attenuation or loss measured in decibels. As we have the fibre relaunch from point A to point B, the power coming from the laser will reduce due to the scaling of the light and due to the loss when we travel a distance. So depending on the condition of the fibre, depending on the length, typical fibre loss could be 0.20dB/km - 0.35dB/km. although in some regions fibre loss may be as high as 0.5dB/km. It may be the dark fibre, ageing or all of the connectors.so when we average the loss over the length , 0.5 dB/km to 0.6dB/Km can be obtainable.
From the link perspective,The number one basic link budget engineering are fibre loss, spice loss,connector loss and safety margin. This should be far less that power budjet. When we launch at power level from point A to Point B to a lower level by transmitting and receiving power over the fibre link we get loss, after all most of the optical networks last for 5, 10 or 15 years.
On top of that is another concept to know which is the concept of transmission window. e.g for 800 ,1310 and 1550 wavelength in manometer(nm). This is referred to the band of the transmission window and each transmission window obviously has different profile because of the fibre.
NGT is a Nigerian Based company. we offer services on optical products and we have customer in Asia-pacific where we deliver software-defined networking infrastructure solutions, enabling global service & content providers to scale their networks and their businesses in Data Centres interconnections. we also have customer in the service provider space that deploy WDM solutions.
NGT systems, some of our audience may not have the chance to visit us both in conferences and workshops, If your have specific questions about NGT optical products and about our networking products, feel free to stop at our online chat room with one of our representatives and drop us a mail at corporatesales@ngittech.com.ng to tell you more about the company. right now,
23 September 2016 15.00Hrs G.M.T
Let get started by asking this question. how many of us reading this article have deployed Optical links or engineered one or have designed optical networks or let re-phrase like this, how many of us have designed or engineered an optical transmission link( SDH/WDM)? or a multiple-node optical transport network? ok! like we said this article was designed for someone who have fairly or no prior knowledge of Optical Networking.
We here you say hmmmm. ok not to worry. now we speak from the provider side or provider services, how many of us are considering to lease a wavelength or multiple wavelengths in the next 6-12 months for providing connectivity? one, two ok Thank! you.
Now in reference to this article with a focus on dark fibre or sometimes called in outer regions as grey fibre. How many of you are considering to lease a dark fibre or wavelength services in upcoming months?, Ok excellent! so ok assuming we have our audience reading this article coming from IP networking background and we will just have to level set for those of you who have not been dealing with optical networking.Most of the time if you are dealing with data networking, the router, MPLS switches, layer 2 and above, usually what you see is a grey cloud, you have the edge device CE, you have the core (P) and the edge core demarcation.(PE).
Typically, this can be across countries so you don't necessarily have to care about the underlying physical infrastructure. All we care about is the logical connectivity between the routers and switches. One often needs to know if the routers have a 10g, 40g, 100gig interfaces and how many of this interfaces are available.But depending on applications obviously, you do care sometimes. This is what we see in textbooks from juniper or Cisco.
For optical networking, however, the physical actual fibre map is an important element for optical link or optical network engineering . So what we see and important in any optical networking design is that we always need to know, how the actual underlying topology is being connected;the fibre distance and fibre characteristics to design an optical networks assuming you are planning for an optical networks, optical links, where there is a ring type topology, where there is a mesh type topology, where there is a point-to-point or point to multi-point. topology. these is always an important consideration.
In optical transmission layer, one needs to know exactly the underlying fibre topology, the fibre details and characteristics so that the optical layer and equipment can be dimensioned accordingly.
So let walk through on how an optical network and link can be designed.
In this article, we will look at this from the physics and physical engineering point of view and also from a networking point-of view so that we can see a bigger picture.
A little bit about our background as well, We are fortunate to and have an opportunity to design all networks in this field for the Tier-1's Whether is in the US, North America, Asia Pacific and now Africa.
Let start from the basics which is a point-to-point and answer some common questions for any optical link/network planning. Since we are dealing with fibre optical networks, the condition of the fibre, the length of the fibre, the characteristics of the fibre are very important information before you start designing any optical engineering network of links. For example, the length, obviously you need to know the distance, is it going to be from rack to rack within a data centre.Is it going to be from data centre to data centre e.g TI tO T2 or E1 TO E2,. i.e the fibre distance or fibre topology map for the design or is it going to be from city to city.
Secondly, how many fibre strands do you have? from the extreme case running to vendors of service provider. The only lease or by-fibre is one strand at a time. We mean not fibre pair but one and they want you to do high capacity transmission over a single fibre stand. A low cost provider will like to do that where the business case justifies it. Do you also get a multiple fibre strands sometimes in cases of North America where the providers are so fibre rich. You have multiple fibre in that case you might not need WDM.Right! because each fibre pair can actually be put 10gig capacity, 100 gig capacity and that might be enough where dark fibre is so cheap or so abundant between some locations, countries or some cities.
So after you have understand the connectivity from this point to that point. How many fibre can you get, lease, rent, borrow?
Thirdly is the type of fibre string. Obviously, if you talk about metro, regional or long haul meaning spanning a hundred or thousand of kilometres.In all the cases, it is likely to be single-mode fibre.This is the type of fibre used for long distance transmision whereas multi-mode fibre is more like cross shelf between rack types. Also there are multiple fibre types as well(SMF). standard common fibre (SMF) types are G652 (SMF-28) G653(DSF) G655(NZDSF). In japan, there are some fibres using G653 which are quite very challenging in the way you design that link.There are some techniques which you can use with seebeck equipment over DSF fibre depending on the distance and the condition of the fibre
e.g coning'S SMF-28 is commonly used in todays networks.
Fourthly, the condition of the fibre strand meaning do the strands have a lot of knots in it, connections, a lot of space, air space due to eigen or microbend factor. This affect the overall loss between point A to point B. Why do we care about high loss fibre? This is because the loss is directly proportional to amplifier in the link ie. amplifiers might be required if the fibre loss is very high therefore you will have to buy more equipment to transmit from point A to Point B if the loss is too high. Also the age of the fibre. is it underground or area fibre. These are all very important as it poses varying challenges because the design for a fibre in japan is different from India and Illinois, Chicago. Also germane is the number of splices or connections on the fibre.
Lastly, is your expectation on the bandwidth that you will transport over this fibre link meaning the End of Life (EOL)transmission capacity. This answers the question, how big should "the pipe" be? Do you need 10Gb/s? 40Gb/s or 100 Gb/s or multiple 100Gb/s per wavelength. How many wavelength(s) or "highway lanes" do you need. The End of Life means the life cycle of the network. what is your expectation? right!depending on the capacity you need. Vendors like NGT or whoever will have to design the network accordingly by picking different level blocks to put together the design for you. You want an optimized for the first course, that one approach or optimize for flexibility, that another approach .
For us we deal with the spectrum of customers to the single fibre strand.
The Only one may be HL of 10Gig or NGT want 96 channel 100gig? they won. No questions to ask. we know how to use the capacity. we know that we will grow with that, infact you have to tell us if this platform can upgrade to 200 per wavelength as well. so we have a whole spectrum of requirement. This is very important.
Today as at the writing of this article, we can clearly inform you that terabit link capacity is not uncommon to connect data centres in metro networks e,g in tokyo, japan , hong kong etc. Customers directly buy say give us 500gig between these two point or give us 600gig between theses two points.Very very not uncommon, in order words it very common especially in the datacentre interconnections (DCI)
One of the key thing about fibre is attenuation or loss measured in decibels. As we have the fibre relaunch from point A to point B, the power coming from the laser will reduce due to the scaling of the light and due to the loss when we travel a distance. So depending on the condition of the fibre, depending on the length, typical fibre loss could be 0.20dB/km - 0.35dB/km. although in some regions fibre loss may be as high as 0.5dB/km. It may be the dark fibre, ageing or all of the connectors.so when we average the loss over the length , 0.5 dB/km to 0.6dB/Km can be obtainable.
From the link perspective,The number one basic link budget engineering are fibre loss, spice loss,connector loss and safety margin. This should be far less that power budjet. When we launch at power level from point A to Point B to a lower level by transmitting and receiving power over the fibre link we get loss, after all most of the optical networks last for 5, 10 or 15 years.
On top of that is another concept to know which is the concept of transmission window. e.g for 800 ,1310 and 1550 wavelength in manometer(nm). This is referred to the band of the transmission window and each transmission window obviously has different profile because of the fibre.
NGT is a Nigerian Based company. we offer services on optical products and we have customer in Asia-pacific where we deliver software-defined networking infrastructure solutions, enabling global service & content providers to scale their networks and their businesses in Data Centres interconnections. we also have customer in the service provider space that deploy WDM solutions.
NGT systems, some of our audience may not have the chance to visit us both in conferences and workshops, If your have specific questions about NGT optical products and about our networking products, feel free to stop at our online chat room with one of our representatives and drop us a mail at corporatesales@ngittech.com.ng to tell you more about the company. right now,
