Broadband Network Architecture – Access Network Models

There are many broadband services Service Providers offer to their customers today. As a network engineer you need to know the most common services and their advantages, disadvantages, design characteristics and so on.

To have a great understanding of SP Networks, you can check my Live SP Workshop  and also my new published “Service Provider Networks Design and Perspective” Book.  The Book covers the SP network Technologies with also explaining in detail a factious SP network.  Click here

In this post, I will introduce these services and if I can see interest from the readers, I will explain the design aspects and deployment models of each one of them.


So if you are reading this post right now and interested to know more, put your comments in the comment box below.


Note : I am going to explain broadband services in this post, not baseband, we are in 2017 right !


Access network infrastructure link the backbone network to the customers.


There are two groups of broadband access technologies. Fixed broadband technologies and Mobile Broadband technologies.


You can find many Mobile Broadband articles on the website.


access network infrastructure

Figure 1: Access Network Technologies and the associated infrastructures 


I will explain these technologies and then I will cover how physical locations can be connected in Fixed Broadband and Mobile Broadband infrastructure.


Fixed Broadband 


Fixed broadband refers to those technologies where the end user must remain at the same location to use the broadband service.


Access network is associated with the specific physical location.


Fixed broadband can be provided by wireline , wireless or satellite technologies.


  • Wireline Fixed Broadband 

Wireline fixed broadband service can be received in many ways as well.


         1.    DSL Fixed Wireline Broadband


Traditional xDSL (ADSL, VDSL etc.) service is one way of having fixed wireline broadband service. Today in many continent most common access network technology is DSL.


DSL deployment

Figure 2: DSL deployment and the components 


In DSL access, traditional copper line of the telephone network equipped with digital subscriber line technology.


DSLAM is used at the Service Provider network and customer modem connection is terminated at the DSLAM.


      2. Cable Fixed Wireline Broadband


Second fixed wireline broadband access technology is Cable Broadband. Broadband service is received through cable access by upgrading traditional cable television network.


Customers can receive both broadband Internet service as well as TV service over the same cable.


Figure 3: Cable Broadband simplified architecture 

   3.     Fiber Fixed Wireline Broadband


Third and last fixed broadband access technology is Fiber. You probably heard FTTx before. There are many deployment options of FTTX access for sure.


You may have heard FTTH (Fiber to the home) , FTTP (Fiber to the Premise) , FTTB (Fiber to the Building)  and so on.



Figure  4: Different FTTx Deployment Options 


Fiber access infrastructure is different from DSL and Cable in many ways.


With Fiber to the Home, from the fiber termination device of the Service Provider up to the modem in the customer home, entire access network is fiber.This is the fastest option customer can get.


As you might know finer has much less attenuation and loss compare to copper and coaxial cable.


Much higher data rates can be achievable through fiber. (In theory you can send 300.000km/s over fiber, because the limit is speed of light).


Between customer and the street cabinet can be copper based and DSLAM can be located at the street.


DSLAM to the fiber termination device which is located at the Service Provider Telephone Exchange (In U.S it is generally called as CO (Central Office) )  can be fiber.


This is another way of deploying FTTx service and called Fiber to the Premises/Cabinet or Curb.


In the above figure, third deployment model which is Fiber to the Building is shown.


In this deployment option, fiber is brought up to the building and between DSLAM and the customer modem, connection is copper based.


  • Wireless Fixed Broadband 


Most common technology for the fixed wireless is WIMAX (Worldwide Interoperability for Microwave Access).


Microwave access is much cheaper compare to fiber access for the wireless access operators.


Fiber access infrastructure can be leased from the fiber infrastructure providers by the wireless operator (This is very common among the Mobile Service Providers) or wireless operator can deploy it’s own fiber infrastructure.


In both methods, capital expenditure is higher compare to wireless based access systems.


Thus, today most common wireless backhaul is deployed via microwave as you can see from the below picture as well.



Figure 5:  Wireless backhaul and dominance of Microwave 



With WIMAX, access speed can reach up to 1Gbps and the customer connection speeds depends on the distance from the wireless base station.


  • Satellite Fixed Broadband 


Satellite connections generally used in rural areas where there is no other access network options available.


By the way, when you work in the Network Operator or Service Provider environment, especially if you are doing any kind of capacity planning work (Transport , Access or IP network) , you always hear urban , sub-urban, metro and rural areas.


These are related the number of people per square kilometre.


If the area is so crowded (Generally 4000 people/ sq km) it is called metro, after metro, urban, then sub-urban , least crowded places are called as rural areas.


Satellite connection has much higher latency compare to other fixed broadband access technologies.


Speed increases by reducing latency, increasing bandwidth doesn’t mean faster connection. 


This is another long discussion probably we should make.


When people increase their bandwidth , they tend to say we have faster connection. Thats completely wrong.


When you have shortcut (so lower latency ) you have a faster connection.



satellite connection

Figure 6: Satellite connection 


Last but not least, satellite connection almost always more expensive for the same speed, compare to other fixed broadband access technologies.


Mobile Broadband 


Mobile broadband refers to those technologies where the end user can use the broadband service while on the move and from any physical location.


Two main mobile broadband technologies in 2017 very common, these are 3G and 4G.


These technologies provide different service speeds to the customers and the Service Provider access and the backbone infrastructure is designed in a completely different way.


3G and 4G speeds

Figure 7: Different mobile broadband connection speeds


As I told you in the beginning, we have many mobile broadband technology posts in the website and you can watch Mobile Broadband Technologies webinar which I did with one of the mobile broadband experts worldwide earlier this year.


Fixed broadband technologies due to technical and financial aspects, tend to be prevalent in highly populated areas (Metro, Urban ) and mobile broadband technologies are more prevalent in less densely populated places. (Rural areas).


If you liked this post, share it on social media and put a comment in the comment box below so I know that there is an interest for these technologies among my readers.




23 Replies to “Broadband Network Architecture – Access Network Models”

  1. Nice article, can you pleastell me how Cable Fixed Wireline Broadbande tell me how
    customers can receive both Internet service as well as TV service over the same coax cable. which coupler is distinguish the wavelength.

  2. Educating piece, Would appreciate you discuss each in more details the type and best broadband service that is most commonly subscribed for voice / video and data traffic in an enterprise environment

  3. Hi Orhan
    We follow you from Turkey with pleasure.
    Mobile backhaul networks are growing day to day in the World but A few people give tecnical feedback as you.In next years Microwave and GSM networks will dominate to internet access.
    We will wait for you more Mobile network design solutions .Thank you

    1. Hi. Glad to hear that there are followers in Turkey too. Agree with Microwave , especially I see it with many MSPs.With 5G, we will see more interesting things but financial aspects of Microwave vs. Fiber for mobile backhaul probably will always be there.

      Anyway, I will write more posts on the broadband (fixed/mobile) , fiber infrastructure , cross-borders, submarine/subsea , international networks, peering , remote peering and so on 🙂

  4. I am interested because we are embarking upon building a new Enterprise Services IPoDWDM network to support FTTX. Explaining the details in understand whether to extend services for FTTX on the existing Unified MPLS network or build a new network from scratch.

    1. Hi, I would write a differences between Seamless and Unified MPLS. But very high level, Seamless MPLS involves extending IP/MPLS to the access , Unified MPLS involves MPLS data plane up to the access network but on the access or aggregation network it uses MPLS-TP instead of IP/MPLS.

      There are so many differences between IP/MPLS and MPLS-TP.

      Recently I write an article on MPLS-TP basics which I covered some of those differences.

      Extending MPLS to the access is about scaling and fewer touch points during a service provisioning along with couple other reasons. I covered many deployment models in my CCDE In-Depth workbook, which I highly recommend to any network engineer.


  5. Sir, nice post lots of information. It would be great if you provide more detail on 4G broadband. That’s my field of interest. Thank you once again sir

    1. Hi Omkar. Will do , but meanwhile have a look at the Mobile broadband category at the right side of the blog page. Also from the Resources check free webinar for the same topic.

  6. Dear

    Usually between the access node (DSLAM or GPON OLT) and the Edge Aggregation BRAS we use MPLS Metro to backhaul the L2 VPN between DSLAM/OLT to BRAS. And then BRAS will connect to IP/MPLS Core as CE to reach to Voice Core (NGN/IMS) or Internet Core. My question is, which one is the better option between the below in term of the MPLS design:
    1) Option 1: Keep separate domain between MPLS Metro and MPLS Core (different BGP AS, different IGP)
    2) Option 2: Integrate both MPLS Metro and MPLS Core as single domain either with Single IP/MPLS control plane or Seamless MPLS

    1. Very classical design, almost all SPs for the DSL backhaul use the same.

      In terms of MPLS, there are much more alternative design options. Did you get the CCDE In-Depth workbook ?

      I highly recommend it as I covered MPLS in the access variations in it. You can get the PDF from the website or hardcopy from Amazon. There is no best design , your two options have pros and cons.

      1. Thanks for the feedback. No I don’t have yet this book ccde in depth workbook. Can you advice me how to get/buy the softcopy of it?


  7. Excellent post Orhan,

    It would be interesting to dig more into DSL Fixed Wireline Broadband, Cable Fixed Wireline Broadband and Mobile Broadband, especially their architectures and access methods.


  8. excellent information Orhan.

    It would be nice to understand how we can optimize IP/MPLS network on a small Service Provider network that serves a population of less than a million and 18,300 square km area.

  9. Thank You Orhan,, Good article to gather the scattered pieces with each other.

    Waiting for the SP session in next July for more details and interaction

  10. Thank You Orhan,, Good article to gather the scattered pieces with each other.

    Waiting for the SP session in next July for more details and interaction

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