Matt Squire
Chief Technology Officer Hatteras Networks
(919) 991-5440
During his career, Matt has proven to be a technical innovator. A recognized expert on Ethernet, MPLS, IP, ATM, private networking and VoIP, Matt holds nine patents and has more than...more»»
mid-band ethernet
Posted by Pat from Marlette, MI, US on September 22, 2007
If radio and electromagnetic interference cause a degradation of signal on traditional T1’s and DSL which use 1 or 2 pairs would bonding up to 8 pairs not increase and magnify this interference? Does the speed of the connection decrease as pairs are compromised? Most OSP network troubles are caused by the sheath of the cable being being compromised which in turn allows water to penetrate the cable and break down the insulation of the conductors.This being the case,does the Mid -Band Ethernet connection deal with this physical trouble ,which is far more prevalent and likely in the OSP networks of today, in the same manner as with induced noise?
It is certainly true that interference causes signal degradation, and that the speed of N lines is not simply N times the speed of one line.
There is in fact a significant difference in the potential speed of the first line added to a binder, and the potential speed of the 4th line added to a binder. However, there is relatively little difference between the speed of the 20th line added to a binder, and the 24th line added to a binder. So the incremental impact of adding another line decreases as there are more lines in a binder.
A potential question is how many active lines are there in the binder already, and what is running on them? It turns out the answer to the question varies widely, and very importantly, can't really be predicted at the outset. A crucial part of Mid-Band Ethernet deployment is planning, knowing what rates can be expected for a given customer. The last thing a carrier wants to do is sell a service and not be able to deliver it.
If you have detailed information on the binder make-up, what technologies are active at what speeds, how the cable is twisted and connected, etc., you can make very accurate predictions. However, that
is not possible in the real world. Instead, you must make conservative
estimates, assuming an environment with a lot of interference. When you perform such conservative planning, then you are already assuming a lot of electromagnetic interference, so additional lines have minimal additional impact. One of the most important aspects of our business is developing planning tools making this process as simple as possible for our carrier customers.
Mid-Band Ethernet also deals with other types of interference such as water, bad connectors, taps, etc. These problems generally affect individual lines but not all. With Mid-Band Ethernet, each line trains at its maximum rate, and supports a disparity of speeds within an aggregate group. So that when there are imperfections in some lines, it doesn't affect the other lines, and creates a group with optimal aggregate speed.
What is VoIP
Posted by Raul from New York, NY, US on February 17, 2008
Explain in detail the meaning of VoIP and how does it relates to your product?
Generically, VoIP is simply a term used to capture the mechanisms for the transport of voice applications over packet networks. These mechanisms include the transport of voice payload, as well as the transport of voice signaling applications. The most important aspect of VoIP from the view of an interior network element is that it requires an application hierarchy. Voice applications have certain performance constraints that must be met in order to maintain voice quality, for example. Voice transport, signaling transport, and generic Internet transport are all potential traffic classes that must be forwarded by network elements, each with a different set of performance characteristics.
So to our product, VoIP is one of the main drivers for an extensive quality of service architecture whereby different applications can be prioritized and controlled in order to meet the varying performance targets. Certain traffic can be mapped to very low latency and jitter transport, paths, while others are mapped to more elastic transport paths. Traffic from one customer has to be mapped into one of many traffic classes, in real time, while maintaining and monitoring the performance of each traffic class.
Although VoIP isn't the only application that drives an extensive QoS architecture, it is perhaps the most prevalent today.
ADSL and T1
Posted by Kathy from Los Angeles, CA, US on April 25, 2007
Can you compare/contrast Mid-Band Ethernet with ADSL and/or T1 services?
That's a great question! It's important to know the difference between Mid-Band Ethernet and these more traditional services, so that the benefits of this newer technology can be truly understood.
We'll first look at the comparison between Mid-Band Ethernet and ADSL. ADSL is a wonderful and incredibly popular residential service - it provides a great way to serve the needs of the residential user by maximizing downstream performance and limiting upstream performance. It's perfect for surfing the web and downloading music or games.
Unfortunately, that's not what most businesses need. I don't know about you, but in my business, our job is to create information - perform sales contacts, send presentations, emails, create white papers, transfer brochures, etc. Business need to be producers of data, not consumers of data. This means that the minimal upstream capacity of ADSL is generally insufficient for business applications. Mid-Band Ethernet is a symmetric technology, providing equal bandwidth in both the upstream and downstream directions, and is much more suited to the business environment.
When comparing to traditional T1/E1 services, the most important differentiators are bandwidth and cost. Mid-Band Ethernet can deliver over 7 times the bandwidth of a T1 over the same infrastructure. T1s come in a rigid 1.5 Mbps scale, while Mid-Band Ethernet can offer a variety of flexible bandwidths. Some carriers are offering Mid-Band Ethernet services beyond 40 Mbps, and in flexible increments from 2 Mbps and beyond! It is clear that existing T1 & E1 technologies cannot meet these flexible and growing bandwidth demands.
Another big difference is reliability. Mid-Band Ethernet, as described in an early Q&A here on "Ask the Expert", is much more reliable than traditional services such as ADSL. Reliability is another cornerstone of the business application, and another key differentiator from both ADSL and T1/E1 services.
One final key thing to remember is that Mid-Band Ethernet is Ethernet - it offers the efficiency, simplicity, and flexibility of Ethernet services. Mid-Band Ethernet is based on 2BASE-TL, an IEEE 802.3 Ethernet standard. Although one may be able to layer Ethernet on top of these other technologies, they are not offer native Ethernet services, and instead offer greater inefficiency and complexity by layering Ethernet on top of some other layer.
reliability
Posted by Josh from Wilmington, NC, US on April 13, 2007
This seems just as unreliable as DSL or T1s - is that true?
Mid-Band Ethernet solves the reliability issues that have plagued the deployment of traditional DSL and T1/E1 services. The access network has historically been the weakest link in the delivery of services - with 80-90% of service outages being directly related to problems in the access network.
Mid-Band Ethernet delivers a resilient business-class service by aggregating multiple copper lines into a single Ethernet interface. If there is a problem on one access line, the other lines will remain operational and continue to deliver service. The service reliability increases with each aggregated line. With many carriers bonding as many as eight pair to deliver a service, the reliability of Mid-Band Ethernet compared to traditional technologies can be increased by orders of magnitude.
You can compare the Mid-Band Ethernet approach with traditional DSL and T1/E1 pretty easily. In most cases, T1/E1 is delivered over two access lines, and if either line has a problem, the entire service is down.
Mid-Band Ethernet uses multiple access lines to increase reliability, not decrease reliability as in a T1/E1. With DSL, there is generally no resiliency - one line, one single point of failure. And when using technologies that are easily susceptible to variable noise like radios or electromagnetic interference, the situation can be very unstable.
Mid-Band Ethernet is more resilient to such outside plant noise.
And finally, Mid-Band Ethernet can be delivered with carrier grade equipment that focuses on SLAs for a quality experience for the enterprise customer. Mid-Band Ethernet is not residential DSL out of your every day Internet DSLAM. Mid-Band Ethernet needs to be delivered from carrier Ethernet equipment that is focused on QoS, reliability, services, and Ethernet service flexibility, so that the business customer receives the value and benefit of metro Ethernet - all without the expense of fiber deployment.
How does Mid-Band Ethernet work with other copper-based services in terms of spectral compatibility?
The simple answer is that Mid-Band Ethernet services are spectrally compatible with all other access technologies, in North America and internationally.
But spectral compatibility is a difficult subject; every region has its own spectral compatibility guidelines that must be followed. This means that the speed and performance of Mid-Band Ethernet, or any copper based technology, is geographically dependent.
In North America, for example, spectral compatibility is governed by T1.417. Mid-Band Ethernet has been shown to be spectrally compatible with T1.417 with rates as high as 5.7 Mbps per pair. But of course that 5.7 Mbps rate, and every rate, has a distance limitation dictated by T1.417. This produces a rate/reach curve that governs how fast Mid-Band Ethernet can run at each distance while remaining under the T1.417 guidelines.
The situation is similar in other countries, each with its own twist.
But Mid-Band Ethernet can be utilized in any geography as long as it is configured to use those local spectral guidelines.
Mid-Band Ethernet is in many cases the most spectrally friendly symmetric technology available. For example, it has been shown that in many cases Mid-Band Ethernet is more spectrally compatible with ADSL than ADSL2 or VDSL2.
But with spectral compatibility there are many cases to be examined, and many technologies to be compared and evaluated - far more than can be addressed in this limited response. I encourage any interested parties to download the "Mid-Band Ethernet Spectral Compatibility Handbook" from our website (http://www.hatterasnetworks.com/whitepapers.aspx) to read a more thorough discussion of the issue.
