LTE is a 4G Mobile Specification for Multimedia.
It has come a long way since the first generation in 79!
The Data and Voice Networks were completely separated since their creation.
The mobile networks were at the very beginning and the first commercially automated cellular network (the 1G) was launched in Japan by NTT in 1979, initially in the metropolitan area of Tokyo.
In the 80s, the Data Networks were using Packet Switching technology like X.25 and the Voice Networks were using Circuit switching Networks with PABX.
At the end of the 80s, the Data and Voice Networks started their convergence.
UUCP was a popular protocol to interconnect UNIX systems. It was not a piece of cake to manage and was basically an asynchronous communication. The Internet was mostly used by universities and the research community. I remember requesting the forms to get access to the Internet for my company and I recall that you had to sign a form admitting that you would not use the Internet for any commercial purpose!
UUCP was a popular protocol to interconnect UNIX systems. It was not a piece of cake to manage and was basically an asynchronous communication. The Internet was mostly used by universities and the research community. I remember requesting the forms to get access to the Internet for my company and I recall that you had to sign a form admitting that you would not use the Internet for any commercial purpose!
With the 90s, slowly digital lines replaced the Circuit switched analog technology. ISDN became the best of the Switched Circuit for Telephony and expensive Network access and also used as backup for leased lines.
At this time there was a battle for the technology that will permit to support Data, Voice, Video and any Real-Time Traffic. As X.25 could not support this convergence, many people were introducing ATM as the solution.
At this time there was a battle for the technology that will permit to support Data, Voice, Video and any Real-Time Traffic. As X.25 could not support this convergence, many people were introducing ATM as the solution.
The network infrastructure with the minimum speed of 155 Mbps for the trunks lines and more required by ATM was not yet widely available. Same problem with the ATM switches which were still very expensive devices as the ASIC to work with the 53 bytes cells were not yet widely available components.
Waiting for ATM wide availability, Frame-Relay, a lightweight version of X.25 was the interim solution to fill the gap with X.25. Frame-Relay was the first network that was really able to support both Data and Voice traffic. Voice Over Frame Relay became very popular thanks to FRF.12 fragmentation. CISCO was a very active member of both ATM Forum and Frame-Relay Forum.
At this time, no one or very few would have bet on VoIP! The ATM scientists were sure to be in the right track for the future of the converged Networks and the VoIP supporters were not considered as really serious people. The IBM choice was to replace Token-Ring with ATM 25Mbps for the LAN access. IBM was also promoting SNA LU6.2 with APPN for peer-to-peer applications. This was the last IBM attempts to sell SNA as the solution for Networking. After this they just followed everybody with TCP/IP.
The first "modern" network technology on digital 2G (second generation) cellular technology was launched in 1991 in Finland on the GSM standard.
Also at the same time IPv4 addresses were mostly consumed and many people were looking for the IPv4 successor. CLNS from the OSI protocols with its NSAP address up to 20 bytes, 160 bits long was the best candidate. Digital adopted OSI for DECNET Phase V. ISIS, its routing protocol, the OSI version of OSPF became very popular with the ISPs, as it was an integrated routing protocol capable to build concurrently CLNS and IP routing tables. Novell ported ISIS to announce IPX routes and SAP services and called this protocol NLSP.
The IETF was still working on IPv6 at this time and RFC2460 was only published in 1998. In the meantime, NAT was keeping the Internet business growing.
In 1998 I was very proud to teach the 5 days CISCO ATM Training, CATM. It was so much fun but at the end of each session I was talking with some students convinced that the future would be Gigabit Ethernet and IP! They were feeling that ATM was too complex and LANE will not scale. They were right but ATM with its UNI, PNNI, LANE, NHRP and all the rest was such a pleasure for a geek that I was also very enthusiast about it! In the next room, a colleague was teaching the IPv6 course and for me IPv6 was pure Science Fiction!
It is also at the end of the 90s that Cisco introduced TAG Switching that became MPLS after standardization. Most Service Providers started to study the migration to a new MPLS backbone, as MPLS-VPN was great to share a PE with many customers instead of having a dedicated router for each customer.
It is only in 2001, that 3G (Third Generation) was launched and again in Japan by NTT DoCoMo on the WCDMA standard. 3G was the first standard allowing to surf the Internet from a mobile phone and have an access to multimedia content.
No one was using ATM for Voice, Video and Data as planned but ATM was still popular at the Service Providers. The Service Providers had two layers of Networks. A WAN backbone allowing them to configure ATM, Frame-Relay or even X.25 links for customer access or some higher speed links to build their MPLS backbone.
But also at this time, people were starting to realize that ATM was greater on the paper than in the real life! ATM was hitting its first big scalability issues. Some big LANE sites were collapsing under the traffic, as the BUS was not able to replicate the Broadcast and the Multicast.
Soon it became obvious that ATM would not work with the Multi-Gigabits networks and VoIP was now considered as the solution for converged networks. ATM was slowly replaced everywhere by all-IP networks with POS or faster and faster Ethernet links running 10Mbps, 100Mbps, 1Gbps, 10Gbps and now 100Gbps!
In the very early 2k, John Chambers predicted than in about 10 years, the people would not pay for the Voice traffic anymore. This is exactly what happened in France with the ADSL and later the Fiber. Most people pay a flat rate for the Internet Access, the Television and the unlimited Telephone over IP, now including the mobile.
IPv6 became a reality at the end of the 90s. Mobility Support for IPv6 (rfc3775, June 2004) enhanced the IPv4 version and permitted to an IPv6 node to roam across any IPv6 subnets without changing its address. The Mobile Node always seems to be connected to its home link while the user is actually visiting many subnets. This is the condition to keep the transport connections up and not restart the application when you move!
With more and more connected people, the smartphones, the improved support of Mobility and more… IPv6 became the key for the Next Generation of Mobile Networks. 4G and Long Term Evolution (LTE) rely on IPv6 to provide enough addresses and to support the mobility.
LTE is a 4G Mobile Specification for Multimedia application designed to provide Multi-Megabit Bandwidth, more efficient use of the radio networks, latency reduction and improve mobility.
LTE aims at providing:
- Up to 300 Mbit/s in the downlink
- 75 Mbit/s in the uplink
- one-way latency less than 5 ms between terminal and base station
- handover in less than 1 RTT
- reduced cost in network deployment
In the heart of LTE is Mobile Support for IPv6 and more precisely Proxy Mobile IPv6 (rfc5213). A proxy mobility agent performs signaling on behalf of a mobile device (MN) attached to the network.
Two new network functions are defined in PMIPv6:
- The Local Mobility Anchor (LMA)
– Provides the home agent function within a PMIPv6 domain, being the topological anchor point for the mobile node’s care-of address.
- The Mobile Access Gateway (MAG)
– A function of an access router responsible for triggering the mobility-related signaling on behalf of the attached mobile device.
LTE Initialization is following:
- The MN enters the PMIPv6 domain and attach to an access-link.
- The MAG verifies the MN Identity and Authorizations.
- If OK, the MAG helps the MN to get all the configuration: address, default gateway,…
- The MN considers the PMIPv6 domain as a link
- The MN sends a RS (Router Solicitation) to the MAG.
- For updating the LMA about the MN location, the MAG sends a PBU (Proxy Binding Update) to the MN’s LMA.
- The LMA sends a PBA (Proxy Binding Acknowledgement) including the MN home network prefixes. It creates the Binding Cache entry and sets up its endpoint of the bi-directional tunnel to the MAG.
- The MAG sends a RA: Router Advertisement to the MN. The MAG can emulate the MN’s Home Link
- The MN can be configured using SLAAC or DHCPv6
- Then the MAG keeps an eye on the Mobile Node and trigger the mobility-related signaling on behalf of the Mobile Node. It is as simple as that!
PBA/PBU Signaling must be protected with IPSec! Data Protection is Optional
Cisco, today, offers a mobile gateway on its 7600 series routers by way of the Service and Application Module for IP (SAMI). But they will not be LTE gateway capable until LTE specific software is available for it. Whatever the case is, Cisco calls themselves LTE Ready, though their SAMI is incomplete solution.
Fred BOVY, CCIE #3013
fred@fredbovy.com
About the author:
Fred Bovy, CCIE # 3013, is a CISCO Instructor and Networking Expert consultant with more than 20 years of experience. For the past 10 years, Fred has been working on IPv6 and Service Provider issues. As an IPv6 IOS dev-test Engineer for Cisco, Fred developed a strong expertise with features like 6PE, 6VPE, Netflow for IPv6 and SEND, and performed dev-testing for all these features. Fred wrote the test plans and the TCL Scripts for automating the features testing, and has a deep, code-level understanding of IPv6. In the classroom, Fred inspires his students by bringing in his extensive experience with designing, optimizing and troubleshooting IPv6 for Service Providers and Enterprises.
fred@fredbovy.com
About the author:
Fred Bovy, CCIE # 3013, is a CISCO Instructor and Networking Expert consultant with more than 20 years of experience. For the past 10 years, Fred has been working on IPv6 and Service Provider issues. As an IPv6 IOS dev-test Engineer for Cisco, Fred developed a strong expertise with features like 6PE, 6VPE, Netflow for IPv6 and SEND, and performed dev-testing for all these features. Fred wrote the test plans and the TCL Scripts for automating the features testing, and has a deep, code-level understanding of IPv6. In the classroom, Fred inspires his students by bringing in his extensive experience with designing, optimizing and troubleshooting IPv6 for Service Providers and Enterprises.
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