Atlantic Data Networks

Spanning Tree Protocol

IEEE 802.1D

By Scott Bailey

Spanning Tree Protocol is a standard for LOOP AVOIDANCE on a network.  A loop in a local area network can bring the network down.  Therefore a strategy was designed to avoid this.

Prior to the development of the standard for Spanning Tree Protocol the second graphic would have resulted in a condition known as a “broadcast storm” in which all devices on the network that send broadcasts would send their broadcast out and a loop would occur.  The switches would basically be shut down.

Why do we want a loop in our network?

Fault tolerance is the primary reason to put redundant links in your network.  My initial drawing is probably not the best example because it looks like three switches, probably in the same network closet. A switchport could fail or a cable perhaps and you would isolate part of your network but a more interesting scenario is when you have multiple closets or even buildings connected by fiber optic cables.  Someone somewhere could break that fiber and strand a part of your network and it’s users on a virtual desert island.

If you review Graphic C below you will see a scenario where you might want those redundant links connecting your switches.  Enter Spanning Tree Protocol to allow you both redundant network links while still avoiding those dangerous network loops.

How does STP (Spanning Tree Protocol) achieve this miracle?  It uses an algorithm to calculate the possibility of looped links by determining a Root Bridge and the possible pathways back to the root.

The preferred link back to the Root Bridge is defined as in forwarding mode.  This is the path to the root of the network that will be used.  Any other port that may eventually lead to a connection to the Root Bridge is placed by the Spanning Tree Algorithm into a Standby mode which is referred to as blocking mode.  In the event the forwarding port fails due to cable or hardware failure, the blocking port becomes active and enters forwarding mode.  Thus, the redundant link can now work to eliminate some portion of your network from being “stranded.”

scottbailey100@gmail.com

Wish you would step back from that ledge my friend.

This is the opening line in a song by Third Eye Blind called “Jumper.” This song came to mind this morning as I have just survived one of THOSE weeks.  My job (NETWORK MANAGER) if you hadn’t guessed can often be really awesome.  I get to work with a lot of smart people, and yes some smart lawyers too.  I am able to work with some really cool technology and I have been able to follow my passion to design and build networks in every Federal Courthouse in my state.  Technology is constantly evolving and I am charged with keeping current with the newer equipment and seeing how we can apply it to help make our client base more productive.  I love that aspect of my work.

But then there are times . . .

Once those networks I have designed and built are in place then the four letter word called WORK kicks in.  You see the Judges and attorneys I work with are doing very important work.  I respect them tremendously.  They spend a lot of their time as court cases move through the system preparing Judicial Orders and responses to motions and Jury Instructions which document these cases as they move through our system.  A great deal of their work product exists as electronic data that is stored on file systems that are maintained by . . . your friendly network manager.

Networks and File servers are machines

That’s right all of that work product that the attorneys are producing is stored on equipment.  And equipment does occasionally malfunction.  And who is tasked with diagnosing the problem and correcting it when there is an equipment failure all the while trying to keep hundreds of people happily working away?  You guessed it.  I do have some really good folks working with me but the buck stops here.

Sleepless days and sleepless nights

I’ve been doing this a long time (twenty years in my current position alone.)  When you’ve been doing this type of work for a while you tend to notice when things are not working exactly right.  You sort of develop a sort of Spidey Sense about certain types of problems.  And when you have Terabytes of data representing the work product of thousands of hours of labor performed by hundreds of attorneys stored on equipment that you all of a sudden seems to be acting flakey . . . well you get the picture.  These are the times my job royally sucks! Because believe me if my data is in peril I am not a happy camper and I am not sleeping much.

“If we didn’t have the occasional problem we wouldn’t need a network manager.”

That is a quote from one of my bosses.  He is absolutely correct but I do take my responsibilities seriously and I do my best to provide a stable network that keeps our folks productive and with no service outages.  If they are working I am happy.  If they are not and it’s a failure of a system I designed, built or purchased then old Scotty is no fun to be around.

Life is good today

One of my favorite summertime songs is “Toes” by the Zac Brown band and the opening verse of the song goes like this.

“I got my toes in the water, ass in the sand
Not a worry in the world, a cold beer in my hand
Life is good today Life is good today”

So when you fix the problem that most people didn’t know they had and you see your systems humming along then life is good today.  I like these days better.  And remember . . . be nice to your network manager . . . especially if he looks nervous because he might just know something you don’t.

Happy WiFiing!

Any Questions feel free to email me at scottbailey100@gmail.com.

scottbailey100@gmail.com

Planning Prevents Poor Performance!

I did drop the fifth P in this old slogan for the benefit of the faint of heart.  When you are planning a Wi-Fi implementation it will serve you well to spend some time considering many topics to assure your staff and customers are not frustrated and you wind up having to spend a lot of extra money later to correct what could have been done properly on the front end of the project.  Let’s talk about what happens in the planning phase.

Begin with the end in mind.

What are your goals?  How many square feet are we trying to cover?  How many BYOD’s (Bring Your Own Device) are we attempting to service?  How secure do we want this network?  Are we going to “hide” it from the public?  Are we going to allow “guests” to access our new Wi-Fi?  Once we talk about these things we can get an idea about how we want to map out the new network.

A proper plan WILL include a Site Survey.

I use a professional Site Survey tool set that includes a mapping software and a custom Wireless Network Access card that accounts for interfering radio waves and will help you to do the best placement of your access points.  A blueprint of the facility is loaded into the software and you begin your Survey and indicate where you are on the blueprint so that it can assist you to in developing your plan.  Wall surface materials are taken in to account as well as obstructions such as metal filing cabinets, refrigerators and other appliances.  Competing radio signals are recorded and you can also plan for what channels and what frequency band is best for a particular part of your building.

We still need cable installed.

Some folks might think why do we need cable?  Isn’t this a “Wireless” network.  While you can extend your radio signals in a mesh network implementation you will not get the same performance that you can have with a hard wire connecting each Wi-Fi Access Point back to the network.

Hardware and power considerations.

Not only do you need to make decisions about what hardware will be involved in the project.  You will need Access Points and a network switch.  Are you going to add power to service the Access Points or will you deliver power via a Power Over Ethernet switch or with a power injector?

Let’s get this down to numbers

We are going to need to budget for the following items.

• Site Survey and plan development
• Cable installation
• Switches and Access Points (factoring in power)
• Network installation and configuration

With all of that being planned for you will still need to make decisions about how you want to secure your network and I’ll go that in my next blog entry

 

Best of luck to you in your project!

Happy WiFiing!

Any Questions feel free to email me at scottbailey100@gmail.com.

scottbailey100@gmail.com

A heck of a Mesh we’re in!

Ok so I’ve written ad nauseam about the beloved radio signal and how it travels and I may even have mentioned “the bad boys of radio,” as defined by Alex Hills in his book.  But now it’s time to solve the problem of having spotty Wi-Fi performance in part of your home or office.

 

Define the issue

Where are we having the breakdown in Wi-Fi service?  Is it between floors or at one end of the house?  What is in between your Wi-Fi router and the area where we get the “less than optimal” service?  How many walls?  (A sheet rock wall with no wallpaper will degrade your signal by about 3 dBm.)  This is not enough in itself to cause a major breakdown in coverage.  However, if we cover that wall with a metallic wallpaper the radio waves can be reflected and not penetrate straight through the walls.  Further, if we start adding more walls and more distance the signal will be degraded and at some point it may drop below the -70 dBm we need for reliable internet connectivity.  Add in some kitchen appliances or an elevator and we really begin to have a problem.

What’s up with the Mesh?

In the early days of Wi-Fi networks there was typically one copper (cat 6) wire connecting an access point back to the core of the network wherein the router would be located to connect to other resources such as the Internet.  With the development of the first Campus Wide Wi-Fi network (at Carnegie Mellon University in Pittsburg) there were spaces where it was not feasible to install a cable.  The solution?  A “mesh” network wherein the Wi-Fi signal is extended by another radio picking up the signal and repeating it to extend the range of usable wireless signal.  These repeaters are also called Wi-fi Range Extenders.  (Being an old cable jockey myself I love the reliability, security and performance of a piece of copper transmitting my signal but there are times when you just can’t get the wire where you want the performance.)

Wi-Fi to the rescue

There are many options to choose from to extend your Wi-Fi but one of the most convenient and better reviewed options is the TP-Link AC1750.  It does not require any counter or table top space and you can plug it into an outlet.  You can get it for about $100.00 and you can order one here.

https://www.amazon.com/TP-LINK-Extender-Gigabit-Ethernet-RE450/dp/B010S6SG3S?ie=UTF8&ascsubtag=WC17848&linkCode=xm2&tag=thewire06-20

Location Location Location!

I once met the owner of a very successful business and a grand opening of his 14^th store called “Party Town.”  He told me he’d been poor three times and he’d been rich three times and there were three secrets to being successful in business.  Location . . . Location . . . and Location.  To be successful in correcting your Wi-Fi weakness you will need to implement the same strategy as “Mr. Party Town.”  You will need to assess where your signal begins to degrade and place your range extender there.  It will need a strong enough signal from the primary Router/Access Point to be able to pick up a clear signal and boost it to the location where you are suffering from the bad service.  Hallways are good.  They are normally in the center of a house and may minimize the reduction in dBm as there should be few walls to cause signal degradation.

Perfection Exists in the Great Reward

I need to take a moment to point out that like computers and other things if you use a wall plug type Wi-Fi extender you will on occasion need to “reboot” it by unplugging it from the wall and plugging it back in.  The table top units are less prone to need to be power cycled so if it’s going to be a problem to reboot the unit here is a link to a pretty highly reviewed table top style competing unit.

https://www.amazon.com/dp/B00KTLG9AK?ref_=pfb_102i2m9hgngl68ki2e3e14n9n44n&tag=hydfbook0e-20&ascsubtag=pfb-P01-V01-O3-B110

The Linksys AC1200 is a little cheaper but has the down side of needing table top or counter space and an external power supply has to be plugged in somewhere.

Best of luck to you in your project!

Happy WiFiing!

Any Questions feel free to email me at scottbailey100@gmail.com.

scottbailey100@gmail.com

I get good Wi-Fi service on the ground floor but my second floor service is for #%$?

This is a very common problem and there are multiple strategies to combat it.  But let’s take a minute to try to find out why.

Radio Waves are funny critters

In a nutshell Wireless Networking (as defined by IEEE 802.11 standards) uses radio waves.  Radio waves have to travel from your portable device to your router for the whole thing to work right?  Well radio waves have certain characteristics.  They travel in straight lines from their point of origin out in a sort of orbital fashion.  Visually think of a ceiling fan. The radio waves travel out from the center of the fan (antenna) in all directions.  In a perfect world the waves would make a circle and the further from the center the signal will degrade until at some point it dies completely.

Let’s take a look at the good old Linksys WRT54G.  This thing is like the Honda Accord of Wi-Fi Routers.  They have sold millions.  Have you ever gone to connect your phone to a wireless network in a new place and seen the network called LINKSYS?  It could very likely have been one of these.

 

On top of the unit you see two antennas pointing directly up.  Now remembering how the signal travels, the optimum service levels will be achieved in a circle horizontal to the direction of those.  Thus, (and here’s the A HAH moment) the best service provided by this unit will be on the floor where it is placed.  The folks on the second floor are likely screwed.  The signal will travel some vertically but it will not be as robust as it will be on a horizontal plane with the direction of those antennas.

Next up.  How do we FIX this kind of problem.

 

Any Questions feel free to email me at scottbailey100@gmail.com.

2.4GHz or 5GHz Wi-Fi. . . . What difference does it make to me?

There are so many options to choose from when adding wireless access to the Internet at your home or business.  Which one is the best one?  The correct answer . . . is YES.  In other words each has it’s place and depending on your needs either could be right for you.

Isn’t 5GHz more than twice as fast as 2.4GHz?

No it’s not.  These numbers refer to the frequency at which the waves modulate from peak to trough.  This is not referring to a throughput speed.  Think back to Sixth Grade science class when you had to draw sound waves.  A base singer in the choir doesn’t necessarily sing slower than a soprano. (What a mess Queen’s Bohemian Rhapsody would be then!)

What’s so good about 5GHz Wi-Fi then?

802.11a band routers operate at 5Gh.  802.11ac and 802.11n can operate at both frequencies.  What’s so good about 5GHz?  You have 23 channels at this frequency so interference between competing neighbor access points is likely to happen less often.  (2.4 GHz devices only offer 11 channels and only 1, 6 and 11 do not bleed over on to each other.)  Also, there are less household devices competing in the 5GHz space.  (Microwaves, garage door openers and cordless telephones all can interfere with 2.4GHz Wi-Fi signals.)

Why wouldn’t I just go with the 5GHz then?

Here is the negative aspect of the newer, less crowded 5GHz radio devices.  The higher frequency of the waves at 5GHz means they tend to degrade faster than the lower frequency waves.  Thus, your signal range is reduced.  Also, these higher frequency signals are more subject to being degraded by obstructions, such as walls and doors.

Which is better?  Are you trying to use only one device to cover a fairly large space?  You need to stick with a 2.4GHz router.  If you are dealing with a smaller space and there are microwave ovens and cordless telephones in it?  Go with the 5GHz router.  Or be like me.  The last router I purchased was an 802.11n band router.  The kids’ room was farther away than my office.  I put the lads’ equipment on the 2.4GHz frequency thus reserving the entire 5GHz radio for me.  😉

Later I’ll be discussing how you can handle covering a larger space with a “meshed” Wi-Fi network.

If you have any questions you can contact me at scottbailey100@gmail.com.  Happy Wi-Fiing!

scottbailey100@gmail.com

What’s up with my Wi-Fi?

So your home Wi-Fi doesn’t seem to be up to snuff.  Here are several things you can look at to see about making it better.

 

Wi-Fi access point placement

Depending on your Internet Service Provider they either have their own Wi-Fi Access Point/Router(APR) in your home or they have installed a modem and you purchase your own Access Point/Router[1].

Your average device needing solid internet connectivity with streaming video is going to need a signal strength of -67 dBm from your Wi-Fi router or access point. For just browsing and email you will have a strength of -70 dBm.  Placement of the APR is crucial to these levels.

These devices use radio waves to communicate so there are things to consider when placing your APR.  Distance:  as you move further away from the APR your signal will degrade.  Walls, doors and other objects will degrade your signal.  The heavier the construction the greater the signal loss.  Sheetrock walls will cost you signal strength but brick will be worse.  Metal objects like ovens and elevators will really impede your signal.

Antenna direction

Some APR’s have external antenna.  These can be pointed in a particular direction.  The correct orientation on the antenna is directly up to get the best horizontal range(think of the radio waves moving out like the blades on a fan.)  Radio signal travels primarily out from the antenna so if it is turned in a manner not as to be aimed up from the floor you are sending some signal towards the floor and some towards the ceiling.

It is also worth it to note that if you are attempting to extend your signal for the best service in a horizontal direction you will not be providing your best signal vertically.  Thus if your APR is on the first floor of your house, service to the second floor will be spotty.  Also, if you want the best service from one AP, the basement is not going to be the place to put it.

Interference

Your neighbors WiFi network might be interfering with your performance.  What you say?  Yes.  WiFi uses radio signals.  If you think of the old days when you turned a knob to change your radio station you will remember as you turned the dial, you would receive interference from competing stations until you hit right on the frequency of the station you were tuning in.  Radio signals bleed over into neighboring bands.  Also, many AP manufacturers default to using the same default band.  (Have you ever looked at your phone for a wifi signal and seen the RFID Linksys?  This router is probably the default set up (and guess what probably has the default admin account and password.  Hint:  if it’s a WRT54G (very common) it’s admin admin.))  It’s probably the default channel as well.  The only non overlapping bands for the 2.4 Ghz routers are 1, 6 and 11.  If your neighbor is on 1 you are fine at 6 or 11.  Don’t do like my neighbor and put it on 2.  It will be interfered with by anyone on 1 and 3 – 6.  The 2.4 Ghz AP’s are b,g and n band. (more later on the 5 Ghz Aps.

Just plain PITA interference (Pain In The %#$$)

Many household devices can interfere with your performance.  They tend to be more intermittent but here is a list of items that may degrade your WiFi performance.

• Microwave ovens
• Cordless phones
• Bluetooth devices
• Wireless video cameras
• Wireless peripherals
• PDAs, cellphones
• Fluorescent lights
• Other 802.11 networks – this is known as co-channel and adjacent channel interference. (I covered this in the Interference section above.)
• Bad electrical connections can also cause broad RF spectrum emissions

These are just some things to look at if you’re unhappy with your WiFi performance and I hope this helps.  If this doesn’t work you can have a WiFi tech take a look at your situation.  Happy WiFiing!

 

More later on this topic.

Any Questions feel free to email me at scottbailey100@gmail.com.

[1] The reason I refer to it as an Access Point/Router as it is basically two devices combined in to one.  The Access Point function provides the wireless signal for your device (say a laptop or phone) to connect to.  The Router function is more involved in providing your actual connectivity to the internet.  It will have an interface facing the Internet and another facing your home network and will handle the routing of data from one to the other network.

Atlantic Data Networks is here to help you design, build or even fix your network.  We design WiFi and data/telephone networks in all sorts of environments.  We and find solutions for your networking problems in all types of environments from industrial to historical.  We do site analysis, provide you pre-installation drawings, WiFi site surveys and will do the installations as well.

We’ve been doing this since 1989 and we love what we do.  We’d be happy to assist you and thanks for stopping by.