PTP Backhaul Complete link kit #1

I have been asked a few times on what I would pick for a PTP link. here is what I would recommend as option #1.  You can use the RF Elements link planner to judge how far you can go. If you want to dive deeper you can use the Cambium LinkPlanner, which is a download. This is an unlicensed 5GH link. if you want some real-world data on this link you can visit https://blog.j2sw.com/xisp/the-addition-of-rf-elements-horns-to-a-ptp550-link/

2x Cambium PTP 550
https://www.ispsupplies.com/Cambium-Networks-C050055H001A
PTP 550 Data Sheet

 

 

 

2x RF Elements Ultrahorn
https://www.ispsupplies.com/RF-Elements-UH-CC-5-24
Ultrahorn Data Sheet

 

 

4x LMR Jumpers
https://www.ispsupplies.com/NM-NM-L4-36

 

 

 

8x Cold Shrink
https://www.ispsupplies.com/COLDSHRINK-12MDN

 

 

There are several other distributors to buy from as well. I choose ISP supplies because they refer business to me and do not have a consulting program that competes with my services.

 

How many customers on an ap? wrong question

Several years ago, I did an article on How many customers can I fit on an AP? I figured with the introduction of MU-MIMO and other things, it was time for an update. Several concepts still apply, but we now have Multi-User MIMO, better filtering, and better technology. One of the biggest questions I hear is, “How many customers can I put on an Access point?”. In this article, I will explain some of the ways to answer this question. Some of this will be geared toward certain products but will be an overall way of answering the question.

Thinking in terms of how many customers you can put on an Access Point is flawed thinking. What you really should be thinking of is how much capacity do I have to sell on an AP. From this, you can apply a formula to know how many customers an Access Point can support with quantifiable data.

Firstly, some things to know.  This article applies to mainly point-to-multipoint radios.  Most of your multipoint radios you come across are half-duplex radios.  The radios receive or transmit, but not at the same time. The over the air rate vs. real throughput come into play as a result. More on this later. Before we get into everything we have to know what affects the customer data rates.  I will break this into two sections. Ideal environment and the real world.

The Ideal Environment
This mainly has to do with radio specs and such.  You have channel width, data rates, and signal to noise to worry about.

Channel width is the first thing to consider. The bigger the channel, the more bits you can flow. If we want to use an analogy, we could compare this to a road or a water pipe. The bigger the road, the more cars that can drive down that road at faster speeds. A larger water pipe can flow more water. As with anything, there are drawbacks. The larger the channel, the more susceptible you are to interference.

Data rates and modulation are the next factors.  The higher the data rate the more capacity the client radio has.  Data rates are influenced by the channel width, radio limitations, and environmental factors.  Think of data rates as the top speed of your client radios. Just like a car road conditions are a huge influencer.

Signal to noise is one of the most critical factors overlooked. I have included this in the ideal and real-world sections for a couple of essential reasons. In the ideal environment, radio manufacturers publish the signal to noise needed to achieve max modulation. Modulation should be looked at first when it comes to a radio not performing as well as it should. The first thing I always look at is what is the current signal to noise.  For example, a Cambium 450M (Medusa) access point states,in the Spec sheet, that in order to achieve an 8x modulation, which is 256QAM you have to have a signal to noise ratio of 32dB.  This chart means if your noise floor is a -80, you have to have a signal of *at least* -48.  In the real world, this isn’t always achievable. Physics can fickle that way. If you want to geek on what QAM is you can watch the following video

The real-world environment
As many of you know the real world can be totally different than the lab environment.  Let’s discuss some factors which can alter the modulation rates, which then affect your overall throughput on an AP.

RF Landscape of a link

The RF “landscape” is the most significant influencer. In other words, how noisy is the spectrum? How many other devices does your access point “hear”? I always use the crowded room analogy. If you have a couple of people in a room, it’s easy to hear them and more comfortable to talk faster (modulation rate). As more people enter the room, you have to find a corner with a smaller group to talk (change channels). As the room becomes even more crowded, you have to speak a little slower because those around you are noisy and a distraction. Your modulation rate has to lower to have an intelligent conversation.

Line of sight is the next major issue. If a customer has any obstruction between them and the AP, the modulation level to drop because it has to deal with the extra noise. This is simple physics. Not only does the signal get degraded if it has to pass through objects or even dense air, but it is also deflected. This deflection is referred to as multipath. Other factors that influence modulation are the quality of antennas, the quality of any cables between the antenna and the AP, environmental factors such as bodies of water, and many other items. these are beyond the scope of this article.

On to determining the total capacity of an AP

Let’s take a Cambium ePMP 3000 ap as an example. This is a 4X4 Multi-User MIMO radio.   What this means is it can transmit four streams to a user at once.  This increases the bandwidth to the client. So where does the multi-user part come in? Most clients are not able to take advantage of the Access Point’s (AP) full capacity so the AP talks to multiple clients at once because it has the capacity to do so.

So let’s run some numbers.  The published spec sheet of an ePMP 3000 radio is a total capacity of 1.2 Gbps.  This radio is a TDD system. This means you over the air rate is half of your actual throughput due to the half-duplex nature of the radio.  It can only send or receive at one time, not both.

Now that we know our radio will do approximately 600 megs of capacity minus some overhead we can factor in oversubscription.

Oversubscription
Oversubscribing in the ISP world has been going on since the dial-up days. When managed properly, it is not a bad thing. The theory is that not every user is online at the same time doing the same things. Out of ten households doing things on the Internet at any given moment in time, you may have three or four streaming Netflix, two watching Youtube videos, three checking Instagram/Facebook/Twitter, and one just reading webpages. Let’s say each of them is paying for a 25 meg down by 5 meg up speed package. Out of those 10 accounts the Netflix streamers may be using 5 megs, the Youtube watchers may be using 3, and the rest are using a combined 5 meg. Out of 250 megs of sold capacity, those 10 accounts only use 31 megs at that point in time. Out of those users, only the streaming services are using that bandwidth the most. In an earlier article, I did a video on a Netflix stream at my house. As customer plans have more bandwidth available, they are grabbing data less frequently because they can grab bigger chunks at a time. This blog post illustrates this as well as this video

Here is where oversubscription becomes a moving target. Not every household is the same. Some may have two or three devices that stream at the same time.  Some may only have one.  Some may watch streaming services very little.

So how do you plan for oversubscription?
In today’s world of streaming a 3:1 oversubscription ratio is a pretty safe bet.  Depending on your customers you might be able to go 4:1, 5:1, or even more.  The faster your plans the less time the customer gets on and off the connection.

Formula
So let’s put it all together.
600 megs of AP capacity at a 1:1 ratio
1200 megs of AP capacity at a 2:1 ratio
1800 megs of AP capacity at a 3:1 ratio

For easy figuring, we will say we are selling 20 meg packages.
1:1 we can sell 30 20 meg packages
2:1 we can sell 60 20 meg packages

Will these numbers hold up in the real world? In most cases, they will not due to the real world conditions mentioned earlier in this article.  If you keep all of your customers at high MCS rates you should expect 70-80 percent capacity numbers in a real-world scenario.  Your mileage may vary. So let’s adjust our numbers.

70 percent of 600 megs is 420 megs
420 at 1:1
840 at 2:1
1260 at 3:1

Those same 20 meg packages
1:1 we can sell 21
2:1 we can sell 42
3:1 we can sell 63

Is the above formula absolute? It is just designed to give you an idea. The following link was published today. it shows 72 ePMP clients on a single AP. As I have stated the client connection isn’t the whole story.  Look at the throughput running through the AP to illustrate the formula is highly dependent on your customers and how they use the service. Remember when I talked about channel width and data rates? Pay attention to these in the video.

In conclusion think of how much capacity you have on an Access Point instead of just customer numbers.  The numbers can be impressive, as in the above video, but don’t tell the entire story.  Customer counts on an AP are nice to know and you can take the above formula to determine how many you can put on at what levels.

#packetsdownrange #epmp #rfelements #cambium

 

 

 

Some Mikrotik SXT photos and first thoughts.

I have been wanting to do some photos and thoughts on the Mikrotik SXTR-LTEs and other Mikrotik LTE products. I recently fired one up using dual sims. One is from Tmobile and one is from At&T.  Verizon is pretty nonexistent in my area. I am about 2.5 miles away from a Tmobile tower and about a mile from a fiber-fed AT&T monopole.

As you notice in the following photo I am pretty buried in trees.

My view of the tower. Notice the high-tech holder.

Some initial notes.  Setup of LTE is a very easy process as far as the mikrotik is concerned.  I literally had to put in some information in the APN and that was it as far as LTE goes.  I did set up standard Mikrotik stuff (DHCP server, security, etc.).

Adding the second sim card can be a huge pain due to the location of the sim card slot.  Luckily I had some tweezers that were angled to be able to slide the card in the slot.  These were part of a dental kit I picked up off Amazon for releasing stuck SFPs and the like.

Look for a more in-depth series on Mikrotik LTE coming soon.

LTE components

What is what in the following diagram when it comes to LTE components
eNodeB -Evolved Node B
This is the main component that allows users to connect to the network.

MME – Mobility Management Entity.
The MME is responsible for initiating paging and authentication of the mobile device. MME retains location information at the tracking area level for each user and then selects the appropriate gateway during the initial registration process.

S-GW-Serving Gateway
The S-GW is responsible for keeping track of devices when they move between eNobeB’s. This is typically not an extra piece of hardware just a function of the EPC

P-GW
This is what connects the LTE network to the Capital I Internet. This also is typically not an extra piece of hardware just a function of the EPC

 

Other terms
The S1 interface is described in the 3GPP TS 36.410 specification.

The X2 interface provides connectivity between two or more eNodeBs.

 

Horvath Communications offers free tower co-lo

In an effort to alleviate the ramifications of COVID-19, Horvath Towers V will be offering free tower co-location to rural broadband service providers for a period of six months. 

“With so many families working and learning from home,” company President Jackie Horvath told Inside Towers, “the demand for wireless internet access has sky-rocketed. As such, we would like to partner with rural internet service providers to allow co-location on our tower assets on a temporary basis.”

Applications will be accepted between now and May 1. All inquiries are to be sent to ehorvath@horvathcommunications.com. As part of this program, the broadband provider will be responsible for the cost of installation and the equipment. The installation team must provide proper insurance before climbing the tower. 

https://www.horvathcommunications.com/ has a map with a site list

Compliance Test for LTU and AC gear

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VXLAN and why you should care as a service provider

As some of you may have heard Mikrotik has added in some VXLAN support in the latest RouterOS7 beta.  What is VXLAN and how would service providers use it? Let’s start out with some broad information about VXLAN

Where does TRILL and VXLAN fit in to your network strategy?

The always interesting RFC read
https://tools.ietf.org/html/rfc7348

This document describes Virtual eXtensible Local Area Network
   (VXLAN), which is used to address the need for overlay networks
   within virtualized data centers accommodating multiple tenants.  The
   scheme and the related protocols can be used in networks for cloud
   service providers and enterprise data centers

Boil it down for me. What is vxlan?
In short, VXLAN allows you to create a layer2 network on top of a layer3 network. It allows you to bind separate layer2 domains and make them look like one. If you are thinking this looks like a GRE tunnel, you are correct except the layer2 domains are still separate with tunnels. VXLAN is mainly touted as a way to interconnect data centers. If you are having to use spanning-tree then VLXLAN is an answer.

Okay, but why not use tunnels or MPLS?
VXLAN allows you to accomplish what GRE does without having to change the network design. By using VXLAN you are also able to have standalone layer2 domains that talk to each other. With the tunnel approach, you have to do a lot of manual configuration.

Is this just a data center thing?
VXLAN was designed to solve many of the edge computing and hyper-scale computing issues. Imagine having compute nodes in different parts of a data center or even in different data centers.  You want all of those nodes on the same VLAN.  With GRE you could extend that VLAN, but with VXLAN you can have two standalone layer2 VLANs that are merged together. VXLAN also solves the 4096 VLAN issue.  This is important in hyper-scale cloud computing.

VXLAN benefits in a nutshell

  • increases layer2 segments to 16 million
  • Centralize control
  • Standards-based
  • Scalable

VXLAN downsides in a nutshell

  • Multicast must be available
  • more overhead to layer2 packet
  • no built-in encryption
  • Slow adoption of ipv6 support by open source

What about the service provider? How can I use this?
In a service-provider network, you have things like broadcast issues. Basically, bridging is bad. Your layer2 networks need to be contained. Imagine you are a service provider who is providing LTE services. You may have an LTE VLAN on your network.  Historically you would have to extend your VLAN across the network in order to do management and access your LTE core. Now you have this large broadcast domain across your entire network.  Or worse yet, you have tunnels to other cities or locations you don’t have physically connected to your network.  Now you have tunnels a part of your LTE VLAN.  MTU issues and other things are now a part of your life.

With VXLAN each LTE node can have its own layer2 VLAN but still talk to the others. This prevents the broadcast storms which can occur.

Another use for VXLAN is a way to allow managed service providers to deploy large scale networks over the 4000 limits of VLANs.  You could literally deploy thousands of layer2 segments to tenants

Why I should or should not care about VXLAN as a service provider?
If you just have a couple of layer2 networks to extend across your network VXLAN is not for you. However, VXLAN does allow for multipath routing and other protocols to be extended to remote networks.

VXLAN adds 50+ bytes of overhead to the layer2 frame. In many service provider networks, this is not an issue due to MTU being raised for MPLS, etc.   IP multicast must be extended across the entire network. Mac addresses are used in creating a distribution network across all of the routed layer2 domains.

Large service providers have started looking at segment routing to solve many of the issues I talk about. This causing them to gravitate toward EVPN. EVPN allows for BGP for the control plane and MPLS for the data plane. More on this coming soon.

In closing, VXLAN is an ultra-cool technology and has use cases for service providers.  Other methods also exist to solve these issues in the service provider world. For those of you looking to learn all you can, I will be posting a list of links for my Patreon folks.

Underground boxes for wireless deployments

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