Improve IMS - Don't Replace ItWednesday, July 26, 2006
In my July 10 commentary, I expressed my concerns with IMS along with the hope that others within the wireless industry were aware of these issues and addressing them. As it turns out, a group of companies led by Verizon Wireless was way ahead of me. This week, Verizon will announce an IMS/MMD initiative that has been developed to enhance these standards, making them more open and operator friendly.
Please notice that I said, "ENHANCE IMS/MMD," not throw it away and start over again. The companies working on this initiative understand that IMS/MMD is a great foundation on which to build next-generation infrastructure. The proposed enhancements and extensions are intended to be over and above the existing IMS/MMD standards and, as such, the group will be submitting this initiative to both the 3GPP, 3GPP2 and others for adoption.
This group includes Cisco Systems, Lucent Technologies, Motorola, Nortel, Qualcomm and, of course, Verizon Wireless. The official unveiling of what is being called "Advances to IP Multimedia Subsystem" or A-IMS, will take place Thursday, July 27. Once this project is made public, I expect to see many more companies including wireless network operators, equipment vendors and others to lend their support. The effort put into these enhancements to IMS so far has led to an important initiative and it is hoped that network operators, regardless of the technologies they have deployed, will quickly see its value to the wireless community and support this project.
In discussions with other network operators and equipment vendors, Verizon and the other partners in this project have received positive feedback and encouragement to move forward. I expect that once more wireless and even wired companies have had a chance to review the initiative, they, too, will voice their support for A-IMS and help move it forward in the standards bodies.
While these enhancements were initially designed for the Verizon CDMA2000 1xEV-DO network, it was soon realized that they were applicable to other network technologies as well. When adopted by the standards bodies, they will have an impact on both IMS and MMD in that the revisions to the architectures will add a new level of compatibility to the standards, assuring network operators that IMS and MMD components from multiple vendors will interoperate within their networks and assist them in providing connectivity to other networks and services.
The group also realizes that there are many IMS deployments already underway in wired and wireless communities around the world. The proposed enhancements can be incorporated into these existing systems without having to remove IMS and replace it with A-IMS. Adding A-IMS on top of IMS will help ensure better compatibility between networks and more operator flexibility in handling applications along with Quality of Service (QoS), accounting functions, mobility demands, security and packet flow optimization (PFO).
The enhancements developed by this group include the ability to manage interactions between SIP and non-SIP applications in the same architecture as well as provisions for better policy controls.
Some of the most substantial enhancements are in the area of security, and the goal is to enable network operators to manage and enforce their own security requirements. This includes confirming that any endpoints that touch the network are compliant to the software policy before they are granted access to the network and providing for ongoing confirmation as well as intrusion and anti-malware detection. The results are higher security for applications and services touching the network from the outside as well as higher security within to protect against attacks by devices on the network. A-IMS also provides for a Security Operations Center (SOC) in addition to the standard Network Operations Center (NOC) so each operator can mount a real-time response to any security threats from inside or outside its network.
These security enhancements are some of the most important additions to IMS/MMD since threats to networks of all kinds are increasing each year, and those who want to wreak havoc with networks are becoming more sophisticated. As a result of the inclusion of A-IMS, network operators will be able to take full advantage of the increased connectivity offered by an IP back-end and still be assured of complete control over their networks.
The A-IMS Architecture
If you have looked at a complete IMS block diagram, your first impression was probably about the same as mine: It certainly appears to be a complex system for a technology that will provide so much benefit by simplifying back-end infrastructure. When I reviewed the diagram below, it became apparent that A-IMS is designed to provide all of the current IMS functionality along with the recommended additions. In the process, the overall system has been simplified and tightened, and the number of network touch points to other networks and services has been greatly reduced.
Some will find their eyes glazing over when looking at this diagram, but others familiar with a comparable IMS diagram will understand the changes and their value.
Figure 1: Architecture Overview
In this diagram, you will see that there are a number of differences between A-IMS and IMS. A-IMS is a more simplified architecture, even with the enhancements, and it includes the following elements:
Application Manager (AM)A-IMS has a SIP management element known as an Application Manager. It is similar to the Call Session Control Functions (P-CSCF, S-CSCF, I-CSCF) and PSTN routing (BGCF-Breakout Gateway Control Function) defined in MMD/IMS.
Services Data Manager (SDM)The Services Data Manager is similar to an HSS (Home Subscriber Server), and is capable of being the data repository for both SIP and non-SIP services. The SDM is also the recipient of accounting data from the various elements.
Bearer Manager (BM)A-IMS provides for control at the bearer layer. The proposed A-IMS architecture provides a balanced approach, with service control being managed at both the SIP layer and the IP layer of the network. The Bearer Manager's main roles are policy enforcement point for QoS, accounting, Packet Flow Optimization (PFO), mobility and access policies, security enforcement point, (including firewalls and intrusion detection) and as a mobility anchor point (Home Agent).
Security Manager (SM)A-IMS introduces the concept of a security manager. It provides a "cockpit" for the network, monitoring all network activity and performing correlation and computations of baseline usage. The Security Manager detects anomalies based on programmed algorithms, and then controls network elements to respond to threats. It is the heart of the Security Operations Center (SOC), the parallel of the NOC (Network Operations Center) but for security. The A-IMS approach is intended to provide the carrier with the best of all alternatives. It contains all of the specific functionality that is outlined in the MMD standards, and it drives new enhancements that will allow carriers to offer additional revenue generating services on their network and enhance the user experience for their subscribers.
Policy Manager (PM)A-IMS builds upon the policy functions in IMS/MMD, strengthening its role into the manager of the full set of services provided by the underlying IP network. The PM provides unified management services of not only QoS and accounting, but also Packet Flow Optimization, mobility and access controls. The PM also links the conditions in the network to the behavior of applications that run on the network. This allows the operator to truly manage the way in which the network ultimately supports the applications it supports. To accommodate the realities of system migration, the Policy Manager is flexible enough to implement device-specific or Application-Specific interfaces.
The IMS and MMD standards have been under development for some time and the results ratified by the 3GPP and 3GPP2 are certainly a major step forward into the future when IP is the common core of all networks. These standards provide a great deal of flexibility when it comes to delivering content and services to customers and seamlessly providing cross-network connections. However, as I noted in my previous commentary, there are some issues with just how wireless-friendly the standards are.
I believe Verizon and its partners have made a set of good standards better, with more flexibility in a real-world environment where SIP and non-SIP applications will have to co-exist. A-IMS provides a clear path for enabling network operators to fully control what is carried over their networks and still be able to accommodate the interconnections that will meet the objectives of IP connectivity.
It is vital to the success of both wired and wireless communications that network operators are able to control every aspect of their network, and it is equally as vital for them to be able to provide access to and from their networks in a secure and open manner. At the end of the day, each network operator is responsible to its customers. It is in the business of providing consistent, secure communications links for voice and data services, and it is responsible for protecting its customers from threats to its network from outside and from within. A-IMS is the right blend of existing standards augmented with enhancements that renders IMS more wireless-friendly and gives operators better control over their networks and services -- their own services and services being provided by others over their networks.
I plan to actively support the adoption of A-IMS as a set of enhancements to IMS and MMD. I believe that the wired and wireless communities will also recognize the value of A-IMS and I encourage them support its adoption. Verizon and its vendors have identified problems and provided solutions in a manner that will result in an even better IP experience for all with multiple vendor solutions and a truly open set of standards.
Andrew M. Seybold