Logical Network Segmentation - VLANs

Unmanaged Edge and Managed Layer 2 Edge switches are being used in hardened environments such as industrial, transportation, oil fields and Intelligent Transportation Systems (ITS).  These manufactures have seriously engineered those switches for sustainability in rugged environments.  Similar to the enterprise application, the switches are being used for high-speed connectivity between end nodes at the data link layer.  

Unlike an Unmanaged Edge switch, the Layer 2 switch uses bridging technology to segment the local area networks (LANs) at the data link layer level and intelligently control the flow of data traffic in an organized way.  A multiport switch typically learns about the Media Access Control (MAC) addresses on each of its ports, stores those MAC addresses in the MAC address table and then transparently passes Layer 2 data frames destined to those ports.  When a switch receives a message sent from an end node (host) the switch checks its MAC address table for the destination address. The switch ensures that the unicast frames destined for MAC addresses that lay on a port can only receive the frames and not forward them to all of the other ports.  Therefore, the Layer 2 switch transfers the appropriate data frames to the appropriate network devices efficiently and helps to increase network bandwidth.  The Layer 2 switch creates a separate collision domain (segment) per switch port and each port provides dedicated bandwidth.  Whereas, an unmanaged edge switch or hub has a single collision domain (segment) that allows data frames to be sent to all of the ports except the port that originally received it.  In addition, the Layer 2 switch offers many advance features for network redundancy, logical LANs segmentation, and security. In this blog, I am going to talk about network logical LANs segmentation and introduction to Inter-VLANs network design consideration.

By default, the Layer 2 functions as single network segmentation typically designed as a broadcast domain network.  Within this network design, every broadcast packet transmitted is seen by every device on the network regardless of whether the device needs to receive that data or not.  It works for a small home and office network but is not recommended for medium to large size networks of multi-level devices types, reliability and security applications. The figure below shows how basic Layer 2 switch works in this particular design.  Host A sent a broadcast package into the network that all of the devices within the same network segment receive.

  

The key benefit of using LAN segmentation within Layer 2 switch networks is to create more and smaller LANs to reduce network collision and broadcast storms in the same segment. Virtual LAN (VLAN) is a method of logically segmenting a network by grouping network devices into different sub-networks.  One of the advance features in Layer 2 switches allows us to group switch ports to sub-group without the limitation of physical location. This logical segmentation increases security and broadcast management.  In a VLAN, broadcasts and any other type of communication data are VLAN specific to the same VLAN.  Members of VLAN A will not receive broadcast or send data to a member of VLAN B.  The figure below shows the logical segmentation on the Layer 2 switch network design by using VLANs.

  

VLANs can span multiple switches by using VLAN trunking protocol (Cisco ISL or IEEE 802.1Q) on each switch in the network.  Figure below shows the logical segmentation on multiple Layer 2 switches.

Since VLANs are separate network segments, members in a VLAN require a router or Layer 3 switch to communicate to other members in different VLANs.  Layer 3 switches are routers with fast forwarding done via hardware instead of software like router does. IP forwarding typically involves a route lookup in the routing table.  Similar to bridges, switch routers create separate collision domains on each segment connected to the router, but unlike bridges or switches, routers do not forward broadcast traffic by default.  Therefore, routers create separate collision domains and also separate broadcast domains on each segment.  Figure below shows the VLANs network with a Layer 3 switch or router.  Now all members of different VLANs can communicate to each other via the routing table.

In conclusion, this typical network design is being used mostly in Intelligent Transportation Systems.  More and more legacy hardware and software are being used in transportation. Components such as ATMS software, signalized traffic controllers, vehicle detection, video surveillance, and dynamic message signs with real-time traveler information etc. are a few examples.  These ITS technologies depend on  reliable network communication systems for real-time data communication between Traffic Management Center (TMC) software and field legacy network devices to increase efficiently and improve air quality by reducing traffic congestion,  travel time, and fuel consumption.  ITS network communication systems are designed to meet performance, reliability, scalability, availability, and security standards.

   

Davenport wants to improve traffic light timing, reduce workers’ time

Davenport wants to improve traffic light timing, reduce workers’ time

Life on the Road

I know many people think that life on the road is a series of fun adventures and great food but, surprisingly, it rarely measures up to those aspirations. It is mostly a series of hotel rooms, repetitive meals, and lots of windshield time. The best times on the road are usually unexpected and can happen when the day-in day-out drudgery is wearing thin. One of the most dazzling sights I have ever seen on the road took place at the least expected time. It was mid-January and the weather had been tough over the previous two days with a combination of snow, freezing rain, and then a severe cold snap. It was the second day of that cold snap and I was just hitting the road early in the morning. I was driving on a narrow two lane back- country highway as the sun was breaking out of the clouds and sitting low on the horizon. As I crested a hill the trees closed in on both sides of the road and were covered with ice from the previous inclement weather. The sun struck the ice crystals in those trees and the trees looked like they were made of diamonds. It was dazzlingly bright as the light played in millions of directions at once. The reflections created a sunlit tunnel as they shot across the highway and I was immersed in a bath of brilliance that astonished and awed me. It was a glorious beginning to the day and I still carry that vision with me with the expectation and hope that I will see something like that once again. That being said, life on the road can be an adventure and in many cases it can be a treasured experience. Traveling through the Midwest is a chance to see some of the most beautiful scenery in the world. The diversity of the terrain and seasonal climate combine to create visions of beauty from the subtle to the extravagant. From a hilly field covered in a snowy quilt for its winter’s nap, to the fiery brilliance of a fall- painted forest, and the ever present multi-hued greens of summer the sights are there to be seen by those who chose to look. The elation of seeing eagles swooping over rivers and lakes, herds of deer grazing on the edge of the woods, wild turkeys feeding in the winter corn fields and the annual migrations of the geese and ducks add to the scenery in an extraordinary way. So when the road is getting long and I am missing my family at home I tend to think about some of the scenes I have been privileged to have viewed and it makes me smile and keep moving. The friendship of the clients I meet also plays a big part in keeping me motivated and focused while I travel. With that in mind here is the current list of conferences and trade shows that gbaSI will be attending or exhibiting at in the near future. I hope to see you at one of these events so if you will be attending any of these shows send me an email ( dpershall@gbasi.com ) or call (309-428-3993) to let me know.

Inventory / Audits

Have you ever had a problem with your communication network and had absolutely no idea what to do to correct the issue or even how to start?  Intermittent loss of signal, persistent static on the lines, or just poor performance?   All of these issues are symptomatic of network maintenance and/or operational issues.

Most agencies depend upon the technical skills and abilities of a small group of dedicated individuals to maintain and operate their communications systems.  This is great as long as these individuals are available and working for the agency but inevitably, these experienced technicians retire or move on to new opportunities.  There goes your network understanding and history out the door!!  It is truly amazing that the complex communications systems that exist in most organizations function as well as they do considering the lack of system documentation that is in place.

The first step in getting a handle on correcting network performance issues is having a true understanding of how your network is configured, what systems and devices make up your network, and how everything is connected and programmed.   While documenting your network is not a new idea, it is an idea that’s time has come.  New mapping technologies and multiple softwares are now available that make creating and maintaining the complex communication infrastructure datasets affordable.  These GIS softwares allow you to map your physical network, document how connections are made, record device information and configurations, and prepare reports that are actually usable and informative to the communication managers and technicians.

gbaSI specializes in working with you to assemble and build the critical documentation and datasets you need to successfully manage and operate your communication infrastructure.  Network construction plans sets, cable routing information, connection and splice diagrams, device information, communication system elements, and a whole lot more are mapped and included in the GIS datasets that will be available to you at the touch of a mouse.

Give us a call so we can help you make your technology talk!

gbaSI offers ON-SITE IMSA Certification

Why is IMSA certification and renewal important? This is a question often asked by IMSA’s certified body. It is often a misconception that working in the field every-day is proof enough that an individual is current in their field of expertise. In the public safety field, keeping pedestrians and motorists safe is critical, and IMSA certification / renewal is pertinent to the continued success and safety of your day-to-day job. Safety starts with you; the individual setting up the work zone, in the bucket truck, working in a cabinet, installing fire alarms, striping roads or posting signage. Being current in your field will help ensure the well-being of motorists, pedestrians and you. 

Maintaining mandatory training and continuing education requirements is always a chore! It requires employees to be away from day to day duties for their departments, getting required team members to offsite training classes, and usually includes travel expenses. IMSA certification is required of most Cities, States and Municipality Public Works employees and must be renewed every three years. Unfortunately, most IMSA training courses are only offered at Regional and National Conferences, which can be costly to attend as well as being out of State, which prohibits some Public Works Departments from attending. What is the most efficient way for you to get this critical training to your team members? 

gba Systems Integrators will now bring IMSA training to YOU! 

gbaSI will assist you in developing a customized program of certification, renewal of certification, CEU or retake/challenge tests that you require. Within a day or two of receiving that information, gbaSI will send you a formal quote for the cost of your program.

gbaSI will also work with you to contact surrounding cities or contractors to partner in your certification program. By bringing more students to any class, costs can be shared and necessary training can be obtained for less! Check us out at www.gbasi.com to contact a team member about your personalized certification program!