Investment & Security: Key Challenges to Industrial Ethernet Systems

By Larry Winchester, Ethernet Direct

The world economic situation is causing many companies to reduce costs. This puts pressure on everyone to cut down wherever possible. Industrial switches have always had a much higher price than their commercial counterparts. If you however need the characteristics of an Industrial switch but want to reduce the cost, then the following guidelines will be important. The saying “You get what you pay” has some subtleties that should be considered when comparing Industrial Switches as initial savings may turn into major costs. Many companies confuse or hide important issues or over emphasize others with lower value. This causes confusion or misunderstandings for many first time buyers that may not know the effects of these differences on performance and reliability.

Here are five key areas that you should be careful to understand when choosing an Ethernet Switch.

SNMP Management. Many companies confuse users by claiming their switches to be managed ones. Terms such as Smart, Web Managed, Lean Managed, Light Managed, or just Managed can create confusion between many vendor to vendor comparisons. A managed switch complies with a set of standards defined by the IETF (Internet Engineering Task Force), and it is what all commercial switches use to define a managed switch. Some Industrial Switch vendors will however use a subset of these defined standards and allow SNMP (Simple Network Management Protocol) protocol to access information from the switch. SNMP, like Modbus in the industrial space, is an established protocol. Having the ability to support SNMP calls does not however make the switch managed. This is a method some switch vendors confuse potential purchasers by listing SNMP support but not the full managed specification of SNMP v1, v2, or v3.

Web managed switches for the most part do not support SNMP communications but rely on the web-server built in to the switch to allow management. This can be an effective way to remotely configure and manage the switch but it falls short in providing detailed information to most network management packages. Most suppliers have web managed switches but some may create the illusions that theses are indeed fully managed. The key here is to look to see if SNMP v1, v2 or v3 is listed. The key is to understand that if a fully managed switch is required, to be sure that it is fully managed. Most network experts will recommend fully managed switches for real time or mission critical applications.

As an added benefit, Ethernet Direct switches are compatible with world renowned IntraVUE network management software which automatically discovers, displays and documents the TCP/IP devices of the network. As Ethernet networks bridge the front office with the factory floor, it promises to reduce the complexities and improve responsiveness by interfacing directly to production equipment, creating a common network infrastructure that transcends the office onto the plant floor.

Proper CPU performance and Memory size. Costs can also be reduced by using less memory or a less powerful CPU in the switch. CPU and memory limitations are why some switches cannot be fully managed as they are not capable of processing the SNMP data. Some low end switches used in high traffic or real time applications in the process may be overloaded and problems may occur at these times. Processors may also reset in order to prevent a full lock-up and thus, switches may have intermittent drop-outs.

Memory size affects the number of MAC addresses that a switch can remember. Not having enough memory can cause issues with the MAC and aging tables, and then cause issues. Some vendors, in an attempt to overcome small memory sizes, use “hashing algorithms”, assuming the MAC address would be spread out and can truncate or compress these numbers. This however has caused problems in industrial networks. As Ethernet devices from vendors are relatively new, you may install a series of devices in which the MAC addresses are in sequence. This can create issues as the switch may not be able to distinguish between several devices. Remember, at the Layer two level, the switches only see the MAC address. Be sure when comparing switches that you know the memory size by looking at the MAC address table size and memory buffer. It would not be a wise investment if a switch could not handle the traffic or number of devices as most Ethernet networks will expand in time.

Environmentally Tough. The need for Industrial Switches is mostly defined by the environment they will be subjected to. The harsh environment with vibration, heat, humidity, dirt and electrical noise degrading the life of components is a major cause of these early failures. Temperature range is one of the important areas but not the only one. Industrial switches should be industrial and for this reason plastic cases that can break off of the DIN rail when cables are attached should be questionable. In some cases, the temperature specifications exceed the connected device by a great deal. Many vendors offer versions of the product with wider temperature ranges, so be sure if you need them that you select them. Redundant power inputs with wide voltage tolerance are also an important feature to consider. Power is one of the areas that most frequently will have an outage or fluctuation. Make sure when comparing switches that you consider switches with redundant inputs as having a greater chance to withstand a power problem and thus better than switches that have only one source. A contact closure for a loss of signal or power is also very important when choosing unmanaged switches.

Truly open systems. Many newer switches, including the emergence of Gigabit switches, will use SFPs to obtain flexibility. Small Form-Factor Pluggable transceivers (SFP) provide the ability of a switch to accept a variety of Fiber optic options. In some applications the uses of SFPs have eliminated the need for modular switches that have a very high cost. A good example is the Ethernet Direct HMG-448G that is an all gigabit switch with 4 SFPs and 4 10/100/1000 TX ports. However, be sure to understand if the switch supports an open SFP policy. The switch will accept any vendors’ SFP. Several major companies lock you in to using only their SFP. This has the effect of a non-competitive cost area that can be greater than the cost of the switch itself. This also limits the flexibility to only the options available from the vendor. Since most vendors do not manufacture their SFPs, this is a hidden cost that should be recognized and factored in for the total cost of the switch.

Support by the vendor. Support is a final area that may not be directly associated with the price of the switch but, clearly if you are searching for help, can cost you time, and, time is money. Not everyone is a General Motors or Exxon and thus may not get all the attention when only purchasing a few switches. Make sure you have a direct line to the technical support of the company. Many switches are sold through distributors that can sell everything from push buttons to power plants. Be sure that if you have a question you can get a quick response from someone knowledgeable. There is no worse situation than to be passed around an organization and then finally being told the person who can help is out of the office, and can only return your call tomorrow. The time to respond to a problem if the individual is not resident on the plant floor will mean additional down time. During this time, the process or machinery may also be down awaiting resolution or replacement. 
An efficient web site with easy-to-find products, prices and technical support will be the model for all companies. Monitored 24 hours a day by technically competent people, the website will allow you to get an answer when you need it. Easy-to-find facts and prices will make it effortless for you to know what you are getting and how much will it cost. On its website, Ethernet Direct offers Live Chat program, which allows you to get answers right away to your questions regarding products, quotations, or technical issues. There are Ethernet Direct global partners who are on call 24 hours a day to provide real time full support. Ethernet Direct also offers Educational Link on the website, which is a free-membership library full of educational materials on Industrial Ethernet.
If you follow the guidelines above and become more knowledgeable about the subtle differences, you will become a more informed consumer. Ethernet Direct is breaking the traditional model and believes that you do not have to pay a lot for quality Industrial switches. It will also be important to use the appropriate resource to address basic networking or device connection problems. This will reduce the need to tie up valuable IT / Networking specialists on these local device or connection problems.

Author Biography
Larry Winchester is the CEO of Ethernet Direct U.S.A. He comes from a background of process-control and PLC system. With 30 years of experience in industrial automation and networking, Larry Winchester is well-knowledged in product know-how, design implementation, and market trends. Ethernet Direct is well-positioned to fulfill customers’ needs and markets’ demands by providing a great variety of tailor-made products and services. By choosing Ethernet Direct, you have chosen excellence & long-term commitment.

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