Very Small Aperture Terminal (VSAT) is overwhelmingly the most prevalent mechanism for satellite communications. While most elements of this document cover all forms of satellite communications, for convenience, the term VSAT will be used throughout.
The advantages of VSAT communications are now widely accepted and understood. At a high level the main reasons for this have not changed for many years. However customer management requirements have been increasing rapidly propelled by developments in terrestrial network management.
Additionally the requirements for higher bandwidths combined with increased space segment scarcity have driven manufacturers to develop and implement more and more sophisticated systems to squeeze every bit per hertz, but these have created some of the most complicated management issues in any networking technology.
This is compounded by the generally poor acceptance by most (with certain exceptions, such as iDirect) VSAT vendors have the need to provide adequate management and upstream management interfaces.
VSAT Technology Background
Very Small Aperture Terminal (VSAT) has been in use for over 10 years for a wide variety of applications such as corporate networks, rural telecoms, distance learning, disaster recovery, ship-board communications the list goes on. VSAT technology has enjoyed steady growth, making it one of the most enduring networking technologies. Industry figures show that this growth is set to continue and accelerate.
This popularity is primarily due to:
- Last mile solution
- Suitability for disaster recovery
- Speed and cost of deployment
True global coverage (i.e. no dependence on the quality of local infrastructure) However, if one has, or is thinking of, deploying VSAT, there are a number of unique characteristics that need to be considered, particularly with reference to Network Management.
Virtually every enterprise or organization in the world depends on a computer network: from a simple small business sharing documents and gaining access to the Internet, or global banking ventures transferring billions of dollars a day. Any organization that relies on its network to do business should have some type of Network Management in place. Organizations that rely in some way on VSAT networks generally need a much higher level of Network Management than most.
Network Management is the process of monitoring and controlling a network to increase efficiency and productivity. It is done by gathering, processing and interpreting data about a network, and then performing fault-finding and IT planning on the basis of that information. It also covers change control, security, access and management of all other aspects of network usage.
With networks being essential to the day-to-day operations of all staff, customers and business partners, demand on network performance has never been greater. Network Management ensures that high availability and fast network speeds are being met, or can alert staff to developing issues before they affect the business. The cost of having no, or ineffective, network management can spell disaster for an organisation. Prolonged or frequent network downtime can result in loss of reputation, productivity, revenue or even a decrease in financial performance .
Traditional Network Management
Considerations for VSAT Technology
Nothing that has been discussed so far is particularly revolutionary or ground breaking for terrestrial networks. However is it still something that is typically very badly done by many organizations. This is usually because Network Management is not given enough profile or importance within a company. Most organizations have a dedicated (or a team of) Database Administrators (DBAs). How many organizations have an equivalent number of dedicated Network Administrators to manage and look after the network? Very few, but what use is a beautifully maintained database if no-one can get to it? Having spent several years performing both these roles in the past, I would certainly rate looking after a set of database clusters as easier than managing a typical (multi-technology, multi-provider, multi-equipment, rapidly changing) large network.
The simple fact that there are literally hundreds of Network Management Systems designed for terrestrial networks compared to only a handful of database administration tools provides some idea of the size of the problem. These tools are designed to work on LANS and terrestrial WANS, typically characterized by:
- Low latency. Response times that are less than 100 ms
- Symmetric bandwidth. Upstream bandwidth is the same as downstream bandwidth. There are a few notable exceptions to this such as ADSL
- Discrete failures. A link is generally working or not working; there are generally no partial failures (congestion is user generated and is therefore not a failure of the link)
- Accessible equipment. Network equipment is generally easy to access
- In band or out of band management. Management traffic can be carried either on the network it is monitoring or on a separate network
These tools will not be referred to as terrestrial network management tools, and their vendors will boast support for any IP network, which is true as far as it goes. If all we are looking for is simple red/green icons and a couple of pre-generated graphs then these tools may be enough.
Network Management + VSAT Technology
VSAT Network Management is caught in the middle between opposing forces:
- Rapidly increasing customer demand for online, real time and historical reporting with huge levels of detail, SLA Reporting, QoS Monitoring and many other complex requirements
- Greater and greater sophistication and complexity within the VSAT technologies that make even simple monitoring difficult
- VSAT technologies which are still primarily designed to be standalone and managed only using vendor proprietary tools (although this is changing with some manufactures like iDirect now actively supporting upstream integration and access by other management systems)
This presents a perfect storm scenario, customers are demanding more, the technology advancement is making it harder just to stand still and manufacturer support, in many cases, is limited or worse. We will deal with each of these areas of complexity in turn.
Increasing Customer Requirements
Ten years ago most clients were happy to be told whether their circuit was up or down. Five years ago they would have liked to know total traffic volumes, latency and maybe EbNo/SNR. Two years ago the range of metrics they wanted to report on had expanded greatly, now incorporating packet loss, jitter and starting to breakdown traffic into more detailed component parts. They were no longer satisfied with one set of reports for the VSAT part and another set for their terrestrial parts, they wanted full end-to-end monitoring. However, in quite a few cases, when reporting was presented in an effective way an interesting thing started to happen.
Bucking the trend for wanting more and wanting it cheaper, many organisations started to realise how important this data was to them, and were prepared to pay additional fees to get to it. Clearly this was not (and still is not) universal, but the trend had started.
Today the trend is for clients to want the level of reporting they had on a per circuit basis, but to have this replicated down to Virtual Circuits or Service Classes. For example, where they used to have single metrics per circuit for Jitter, Latency, Packet Loss, they now want these separately for their VoIP traffic class, their Sensor and Telemetry traffic class, their Citrix traffic class and so on. It goes without saying that they want all this information and functionality web-based, in real time (plus the ability to go back months or years for historical reporting) and from anywhere in the world. Oh, and they would like to be notified proactively to their smart phone about anything affecting service, not just outages, but congestion, VoIP chop, overheating equipment and much more!
Increasing Technology Sophistication
The nature of VSAT communications necessarily implies a certain amount of technical sophistication. To get a packet through a shared frequency band from one point on the Earth to another, via a satellite and back again, requires no small amount of complexity. But it is the drive for higher performance, lower latency and greater and greater bandwidth efficiency to match industry growth with increasingly scarce space segment that has driven most of the technical developments and complexity. Automatic power control, advanced acceleration and compression, dynamic QoS and CIR changes and Adaptive Coding and Modulation are well known examples of these developments, and every one brings with it great management complexity.
This complexity extends far beyond being able to simply measure and store additional data series. Many of these techniques fundamentally change the nominal values of several other metrics, so what may be perfectly healthy circuit/network performance one second may be very poor the next. Keeping track of tens or hundreds of metrics, and how they compare to nominal ranges, which are themselves constantly changing, is a nearly unique challenge to satellite communications, and one totally beyond any terrestrial management system.
There is another dimension to the technology sophistication, and this is the rate of change. To determine what is required today, how to achieve it and then implement it is one thing, but by the time this has been achieved the newly presented technological advances also need managing.
This can easily become a never ending catch up process, and is one of the biggest reasons organizations elect not to try to build (or start to build and then abandon) all this management for themselves. The cost and resource required to get up to date and keep up to date with advancing technology driven at ever increasing rates by bandwidth scarcity is a huge undertaking and impossible to do cost effectively for individual organizations.
The final great challenge with VSAT technologies is the lack of both a friendly and efficient management interface and a lack of management standards. Many organizations believe that by adding a standard management stack e.g. SNMP (Simple Network Management Protocol) their management responsibilities have been met (and some of these are implemented very badly). The real question should be is this the right management interface?
For example, a very common requirement is to get data that can only be obtained from the remote device (e.g. transmit and receive traffic, temperate, buffer fill levels, etc). In a typical management scenario there could be 15 of these metrics we want to collect every 60 seconds. Each of these would likely be a 4 byte counter. However under SNMP typical packets sizes are around 70 bytes, requiring 70*15=1050 bytes per minute (140 bps) both upstream and downstream per circuit.
This is as compared to a theoretical minimum limit of 8 bps, or even lower if only changes are transmitted. An addition 130bps per circuit may not seem like a lot but on large networks this can very quickly become significant (126 kbps on a 1000 circuit network).
It is widely accepted that since SNMP has been a defacto standard for management of terrestrial networks and components, it is a perfect solution for all networks. However, with the very high cost of satellite bandwidth this is rarely the case for satellite networks.
The second problematic situation is where a useable system exists but is not standards-based in terms of Network Management.
This usually means that an efficient and comprehensive integration is possible, but requires very complex and customized integration into a Management System. In practice these systems are usually possible to integrate into standard network management systems since they generally only support standards based integration. The final situation it that neither option is available i.e. neither a useable or standards-based management interface. Fortunately on modern VSAT systems this is rare, although it still exists, but there are still many legacy systems in use and it will be many years before these are retired completely.
These issues are VSAT specific, however there are very few pure VSAT networks. Most networks are hybrids, using a wide range of technologies including ATM, Frame Relay, ISDN, VPN, MPLS, Ethernet as well as standard networking equipment such as routers, switches, hubs, firewalls and servers. The Management System for such a network must be able to handle all of these properly and accurately, in addition to all the special considerations made for the VSAT element.
As has been discussed previously, end-to-end management is becoming a critical requirement for most customers, and the ability to both intelligently manage the VSAT component, while cleanly integrating with management systems for other components and providing full end-to-end class based monitoring is the ultimate challenge. But such can also provide great opportunities for time saving, automation, customer satisfaction and generating additional revenues.
About the author
In 2004, Guy Adams was named the U.K.s Network Professional of the Year in recognition for his work for SatManage and its clients. He has overseen the development of a satellite network management system now used in many of the worlds largest and most prestigious organisations. His groundbreaking data correlation, visual displays and trouble ticketing automation form the basis of SatManage, a comprehensive satellite network management suite. Guy is the Chief Technical Officer for Parallels SatManage product.