Basic questions about NGNs

I get questions on telecom, mobile and Internet topics from students in different parts of the world and I try to reply to them all as best I can.  One kind of question that comes up repeatedly has to do with "Next Generation Networks" or NGNs - what are they?  why are they based on packet technology?  how do they support multi-services? etc.  

Recently I answered a whole string of such questions for a Masters student in the UK.  Here are my answers:

Hi  ... ,

For most kinds of communication, packet networks are more flexible and more efficient.  And, as a practical matter, the Internet (a packet network) has become a globally pervasive platform, which indeed can be used to support almost any kind of communication.  Most everything is migrating to the Internet because the Internet is pervasive and Internet technology is by far the highest volume and lowest cost of any communications technology.  So it's natural that any envisioned NGN would be built on packet technology.

The term NGN is a bit loaded, as it normally refers to a telco-centric view of how the Internet should evolve.  My views on that are here:

   http://www.tmcnet.com/ngnmag/columns/articles/126646-ngn-itu-misses-boat.htm

For the latest on how many AS numbers have been assigned see:

   http://www.cidr-report.org/as2.0/autnums.html

For the latest on how many AS numbers are currently advertising routes on the Internet backbone, see:

   http://www.cidr-report.org/as2.0/

The only issue with carrying a variety of services over a common platform is whether you need different relative levels of service (QoS) to support different higher level services like telephony, video, web browsing, etc.  The telco view is that a sophisticated range of priorities are essential (and that the telco should be able to differentially bill based on the higher level service that is being carried).  However, no one has figured out a commercially viable way to deliver QoS over the public Internet.  Also, if there is any requirement for QoS at all, it is for very simple differentiation at just those few points where there are bandwidth shortages.

The richest set of details on what an NGN is envisioned to be is presented in the standards of the 3GPP (the body that provides standards for GSM, HSPA, LTE and other wireless networks).  See: 

   http://en.wikipedia.org/wiki/IP_Multimedia_Subsystem

   http://en.wikipedia.org/wiki/System_Architecture_Evolution

and if you want to read the actual 3GPP specs, you might start here:

   http://www.3gpp.org/ftp/Specs/archive/23_series/23.402/23402-a21.zip

You'll have to dig through documentation on the 3GPP's IMS and SAE if you want to understand their plans for their NGN.  I don't expect any NGN to gain much traction compared to the open Internet and I personally have moved from a business where I supplied products to telco equipment vendors into a new business, netBlazr, where we are revolutionizing the delivery of fixed Internet connectivity in urban areas. So I'm not so interested in NGN any more.  :)

MPLS is an IP-centric protocol layer just below the IP layer which allows Internet Service Providers with multiple routes to define "virtual circuits" between points in the core network.  It's a way to hide (i.e. simplify) an otherwise complex network of IP routers and to channel certain kinds of traffic over specific virtual circuits.  This can be used to guarantee enough headroom for certain kinds of traffic and for other network management purposes.  For example, if you want to give priority to voice traffic, you could route all voice-related IP sessions over a different path (different at the MPLS level) and you could guarantee enough bandwidth on that path so voice traffic was never over-subscribed (i.e. never ran out of bandwidth).  When there was little or no voice traffic, other MPLS virtual circuits running over the same links could use the idle bandwidth, but when voice traffic increases, the voice circuit would get it's predetermined bandwidth.

Indeed, MPLS works by assigning labels (which are inserted between the link layer protocol header and the IP header).  Here's a view of how MPLS & QoS are envisioned to work:

   http://www.huawei.com/products/datacomm/catalog.do?id=2515

This is simpler than the ITU/3GPP view of NGN, but still likely more complex than what most network operators are deploying.  On the other hand, I don't have direct field experience operating a backbone network, so i can't give you the real details.  My impression is that Internet backbone operators use MPLS but only for very simple pre-defined bandwidth allocations between major backbone routers.

I hope this helps,

Brough Turner

 

Comments

[Brad Fallon]

A very comprehensive post. The information are all relevant and significant to today's computer age technology. Internet I agree is the widest form of communication and the cheapest source of information. There will be an increase number of users in the future.

[rental elf]

Nice article, thanks for the information.