Is It the Telco’s “Next Generation Network”?

Telcos around the world have been moving towards something they call “Next Generation Network” (NGN) for some time. Is that the same thing as the Third Internet? Well, there is certainly a lot of overlap, but no, NGN is something quite different.

Historically, telephone networks have been based on a variety of technologies, mostly circuit switched, with call setup handled by SS7 (Signaling System 7).  The core of the networks might be digital, but almost the entire last mile (the part of the telco system reaching from the local telco office into your homes and businesses) is still mostly analog over copper today. The new FTTH service is finally digital (for both voice and data). There was some effort at upgrading the last mile to digital with ISDN (Integrated Services Digital Networks), but some terrible decisions regarding tariffs (the cost of services) pretty much killed ISDN in most countries, including the U.S.

I have just signed up for FTTH service at my home in Cebu, Philippines, for 5Mbps. The cost is about the same as the former ADSL service (about PHP 1700 per month) but with better bandwidth and service quality.

The ITU (International Telecommunication Union), an agency of the United Nations that has historically overseen telephone systems worldwide, defines NGN as packet-switched networks able to provide services, including telecommunications, over broadband, with Quality of Service enabled transport technologies, and in which service-related functions are independent from underlying transport-related technologies. It offers unrestricted access by users to different telecommunication service providers. It supports generalized mobility which will allow consistent and ubiquitous service to users.

In practice, telco NGN has several main aspects:

In telco core networks, there is a consolidation (or convergence) of legacy transport networks based on X.25 and Frame Relay into the data networks based on TCP/IP (for a long time mostly TCP/IPv4, but recently more and more TCP/IPv6). It also involves moving from circuit switched (mostly analog) voice technology (the Public Switched Telephone Network, or PSTN) to Voice over Internet Protocol (VoIP). So far, the move to VoIP is mostly internal to the telcos. What is in your house, company and even cellphone today is mostly good old POTS (Plain Old Telephone Service) – if you are using the primary “phone” app provided by the vendor and supported by your telco. These typically require a SIM, and have an E.164 (numeric) telephone number, like +1-904-555-1212. Real VoIP uses SIP URIs, like sip:lhughes@sixscape.com. There are many alternatives to the POTS service on mobile devices today, including VoIP, WhatsApp, Skype, etc. Most of these are proprietary systems that can’t directly connect to ITU compliant subscribers, or even other apps, except via gateways (there is usually a change for using a gateway to the POTS system).

In the “last mile”, NGN involves migration from legacy networks with split voice and data networks to Digital Subscriber Line (or ideally Fiber To The Home) making it possible to finally remove the legacy voice switching infrastructure. DSL is still mostly on deployed top of legacy copper wires between the home and the nearest DSLAM. One variant (mostly used in home accounts) is ADSL (Asymmetric DSL), which has different download and upload speeds – a typical deployment might be 4 Mbps down and 512Kbps up. The other variant (mostly in business accounts), SDSL (Symmetric DSL) has the same upload and download speeds (e.g. 4 Mbps each). Recently more and more telcos have been deploying FTTH (Fiber To The Home), replacing the old copper wires with optical fiber cables. These can still be asymmetric (lower upload speed), but often are symmetric (matched upload and download speeds).

In cable access networks, NGN involves migration of constant bit rate voice to Packet Cable standards that provide VoIP and other SIP based services. These are provided over DOCSIS (Data Over Cable Service Interface Specification) as the cable data layer standard. DOCSIS 3.0 does include good support for IPv6, though it requires major upgrades to existing infrastructure. There is also a “DOCSIS 2.0 + IPv6” standard which supports IPv6 even over the older DOCSIS 2.0 framework, typically requiring only a firmware upgrade in equipment. That will likely get rolled out before DOCSIS 3.0 can be (DOCSIS 3.0 requires hardware upgrades).

The first “Internet over telco wireless service” in early 2G networks was WAP (Wireless Application Protocol). A “WAP browser” did not understand standard HTML, but a bizarre variant called WML. 2.5G systems improved on WAP with GPRS (General Packet Radio Service), with theoretical data rates of 56 to 114 Kbits/sec. GPRS included “always on” Internet access, Multimedia Messaging Service (MMS), and Point-to-Point service. It increased the speed of SMS to about 30 messages/sec. Even Filipinos can’t text that fast. As with WAP, only IPv4 was supported. EDGE (Enhanced Data rates for GSM Evolution) was the next step. EDGE service provided up to 2 Mbit/sec to a stationary or walking user, and 348 Kbit/sec in a moving vehicle. IPv6 service has been demonstrated over EDGE, but is not widely deployed. HSPA (High Speed Packet Access) has two protocols: HSDPA (High Speed Downlink Packet Access) with theoretical speeds of up to 14 Mbit/sec service, and HSUPA (High Speed Uplink Packet Access) with up to 5.8 Mbit/sec service. Real performance was again somewhat lower, but better than with EDGE. HSPA had good support for IPv6. and primarily (but as of recent versions of the 3GPP specification, no longer exclusively) based on IPv6.  3G was still based on two parallel infrastructures (circuit switched and packet switched). LTE is packet switched only (“All IP”). There are many deployments of LTE. Earlier versions of the specification clearly described LTE with IPv6 mandatory and IPv4 support optional. It has now been reworded to make most aspects “IPv4v6” (dual-stack). The reality is most LTE deployment today are IPv4 only. However, recently many U.S. telcos began providing IPv6 on their dataplans (some are over 90%). A few are even going IPv6-only (no IPv4 service). This can be done on phones with 464XLAT that allow legacy (IPv4-only) apps to work. Virtually all Android phones since KitKat support this. iOS phones since 10.3 will work with IPv6-only. Telcos began using the name “4G” to mean basic LTE over IPv4 with higher speeds.

 

 

So, clearly the Telco’s NGN is moving more and more towards IPv6 in the near future, but current deployments are still mostly IPv4. However, NGN is just as clearly not the Third Internet described here. You might say that NGN (once it reaches 5G) will be just another one of the major applications hosted on the Second Internet, along with Web, E-mail, instant messaging, etc.

There will be much more to the Third Internet than just telephony, including most broadcast entertainment, exciting new possibilities for non-telephonic communication paradigms (fully decentralized instant messaging, and peer-to-peer collaboration), smart building sensor and control systems, and ubiquitous connectivity in essentially all consumer electronics, including MP3 players, electronic book readers, cameras and personal health monitoring. It will also impact automotive design. See www.car-to-car.org for some exciting new concepts in “cooperative Intelligent Transport Systems” that depend heavily on IPv6 concepts such as Networks in Motion (NEMO, RFC 3963) and ad-hoc networks. In fact, only IPv6 is being used in their designs, although it is a slightly modified version of IPv6 that is missing some common functionality such as Duplicate Address Detection. Their modified IPv6 runs on top of a new, somewhat unusual Link Layer called the C2C Communication Network, which itself is built on top of IEEE 802.11p, also known as WAVE (Wireless Access in Vehicular Environments).

5G systems (now being designed) continued the transition to all IP and even higher speed wireless transports. They use an all-IP infrastructure for both wired and wireless. The specification for 5G claims peak downlink rates of at least 1 Gbit/second, and uplink of at least 500 Mbit/sec. 5G requires a “flat” IP infrastructure (no NAT), which can only be accomplished with IPv6. IPv4 address space depletion has already happened before 5G can be deployed, so IPv4 is not even an option. IPTV is a key part of 5G, which requires fully functional multicast, scalable to very large customer bases. That also requires IPv6.

The last gasp for traditional telephony is LTE (Long Term Evolution).

3G systems introduced HSPA (High Speed Packet Access), which consisted of two protocols, HSDPA

2.75G systems introduced EDGE (Enhanced Data Rates for GSM Evolution), also known as EGPRS Protocol). WAP 1.0 was released in April 1998. WAP 1.1 followed in 1999, followed by WAP 1.2 in June 2000. The Short Messaging System (SMS) was introduced. Only IPv4 was supported. Speed and capabilities were somewhat underwhelming.

A major part of NGN is IMS (the IP Multimedia Subsystem). To understand IMS, I highly recommend the book “The 3G IP Multimedia Subsystem (IMS) – Merging the Internet and the Cellular Worlds”, by Gonzalo Camarillo and Miguel A. Gaccia-Martin. This was published by John Wiley & Sons, in 2004. This book says that IMS (which is the future of all telephony) was designed to work only over IPv6, using DHCPv6, DNS over IPv6, ENUM, and SIP/RTP over IPv6. IMS is so IPv6 specific, that some of the primary concerns are how legacy IPv4-only SIP based user agents (hardphones and softphones) will communicate with the IPv6 core. One approach is to use dual-stack SIP proxies that can in effect translate between SIP over IPv4 and SIP over IPv6. Translation of the media component (RTP) is a bit trickier, and will be handled by Network Address Translation between IPv4 and IPv6. Newer IPv6 compliant user agents will be able to interoperate directly with the IMS core, without any gateways, and solve many problems. They are beginning to appear. I am using some hardphones from a great little company in Korea called Moimstone today. IPv6 was not widely enough deployed when 4G was released, so providers began using the name “4G” to basically mean “faster 3G”. The revolutionary changes in IMS were deferred until 5G.