Saturday, September 26, 2009

The need for QOS versus Net Neutrality

In 2003, I made a VOIP call from home while downloading a large email attachment. The DSL line saturated and my audio quality became horrible while VOIP packets (and email packets) were being dropped. Doubling the bandwidth to my home would not have solved this problem. The email download would simply have been faster, but the VOIP call would still have suffered packet loss.
The solution to this problem is 'quality of service' (QOS). Some applications, particularly realtime interactive applications, are sensitive to packet loss. Other applications, particularly bulk data traffic (including email, ftp, backups, software update downloads) are not time sensitive and can have their traffic delayed in favor of the realtime traffic. QOS is the network function where certain applications and traffic are prioritized over others that are deemed less urgent.
The creators of the Internet Protocol version 4 understood that quality of service was a requirement. They included the 'type of service' field in the IPv4 header when it was specified in 1981. When developing IPv6, they cleaned up unnecessary header fields, but still they kept the 'class of service' field in the base IPv6 header. Every Internet Protocol packet sent on the Internet since 1983 (when IPv4 went live) included this service field in the header to enable QOS functionality.
In September 2009, Julius Genachowski, chairman of the FCC commissioners, proposed two new 'network neutrality' principles. Among them was the "principle of nondiscrimination." This proposed principle states 'broadband providers cannot discriminate against particular Internet content or applications.' While there is a valid concern that ISP's may choose to impede applications or content from competitors, the current proposal as stated seems to restrict ISP's from using QOS to prioritize traffic for realtime applications, and deprioritize traffic for bulk data applications.
Due to the apparent attempt to ignore a fundamental building block of the Internet, I oppose the proposed 'principle of nondiscrimination' as written. ISP's need to prioritize realtime applications, while deprioritizing non-realtime bulk-data-transfer applications. In addition, ISP's need the freedom to block applications which do not 'play nicely' in a bandwidth constrained environment. Network engineers know that sometimes particular applications need to be blocked to allow the majority of the network (and the majority of customers) to enjoy adequate performance.

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11 Comments:

Blogger Darrell Root said...

PDF version of presentation is at qos-neutrality.pdf

September 26, 2009 at 8:46 PM  
Blogger Abu Amir - أبو أمير said...

hello darell,

I like your podcasts a lot, very helpful and well addressed.
I have a question, maybe u'd have an answer for it. However, it has nothing to do with today's podcast.
I've seen in some books ( cisco books ) from ciscopress when they talk about < classful boundary > for 192.168.0.0 they say 192.168.0.0/24. And for 172.16.0.0 they say 172.16.0.0/16
Isn't the classful network of 192.168.0.0 a /16, and for 172.16.0.0 a /12.
Please take the confusion away...
thank you all !

October 11, 2009 at 9:31 AM  
Blogger Darrell Root said...

There is a difference between the "default classful netmask" of a particular ip address, and what IP addresses are allocated to a particular purpose.

IP addresses that start with the first bit 0 are class A and have a default netmask of /8. That includes IP addresses with the first octet 0 through 127. By coincidence, 10.0.0.0/8 is allocated to private addresses (RFC1918). So one class-A is allocated to RFC1918 address space.

IP addresses that start with bits 10 are class B and have a default netmask of /16. That includes IP addresses with the first octet of 128 through 191. 172.16.0.0/12 is allocated to private addresses in RFC1918 (this includes 16 /16's).

IP addresses that start with 110 are class C and have a default classful netmask of /24. That includes addresses with the first octet 192 through 223. 192.168.0.0/16 is allocated to RFC1918 address space and includes 256 class-C address blocks.

October 12, 2009 at 7:57 PM  
Blogger Abu Amir - أبو أمير said...

AAAh, I see :)
For some reasons, it didn't come to my mind.
Thanks Darell, for this clarification.
LOVE YOUR PODCASTS...

October 13, 2009 at 8:16 AM  
Blogger Richard said...

Hi,

Your comments about Net Neutrality confuse me, are you saying that ISP's should prioritize certain applications for every application provider or just for their own products. Shouldn't the pipe be neutral and the endpoints, controlled by their customers be the deciders on how traffic is allocated.
If I buy bandwidth, as the customer shouldn't i decide what applications get more bandwidth and not the provider of the pipe. Doesn't that give the Telco's carte blanch to only provide QOS for only their own video and voice applications? This would give us a more limited source of suppliers and tie up the market for the big guys, wouldn't it?

October 31, 2009 at 9:40 AM  
Blogger matthew said...

@richard:

You can, basically what I got out of what he was saying is that the ISPs should be able to prioritize the network that is being transferred from one end of their network to another, not just what you have rented out through them. This way, say your VoIP traffic wouldn't get impeded by someone else BitTorrent traffic.

December 2, 2009 at 10:18 AM  
Blogger Chaz said...

Darrell:

I agree with you that a bulk copy application, e.g. ftp, bit-torrent, etc. should have a lower priority then a VoIP or a video stream. That is reasonable, however, do you think a third party VoIP operator and the ISP's own product should be delivered with the same priority? Or should the ISP have the ability to hinder the third party providers messages with equal priority to that of the ISP's own?

I think that we are going down a road akin to the common carriers of the 19th century, Back in the days of telegraphs and trains, at that time a railroad would give it's own cargo (or its partners) priority over that of unaffiliated entities. At that time (1887) because of the railroads monopoly power over the transport of grain Western farmers to the markets in Chicago & the East, there was the creation of the Interstate Commerce Commission. Of course after the demise of the railroads, and the proliferation of other modes of transport the regulations became more of an anachronism and the ICC was abolished in 1997.

All that said I think we are at a similar point in the history of the Internet, given that there are few broadband providers, and give the market power that they have, there indeed should be rules by which they are made to provide a level playing field to all subscribers.

-chaz

September 5, 2010 at 11:43 AM  
Blogger jonwilson said...

I don't think net neutrality will ever be a good idea. It's something that corporations can take advantage of. The government can even abuse net neutrality to legally breach people's privacy.

telephone recording device

August 9, 2011 at 6:50 PM  
Blogger Joanne said...

I agree with Jon Wilson. While it has its advantages, it definitely comes with a lot more issues.

audio brisbane

October 10, 2011 at 2:37 AM  
Blogger pevensies said...

Hello Darrel;
I am new to the Cisco world working on my CCNA. I purchase several items from Cisco Kits, and have a network setup however I cannot get this network to communicate with the internet. I have look at (several times) your DHCP and NAT Podcast and tried to replicate the configuration at my home, however I still cannot get it to function. If I can send you my packet tracer file maybe you can tell me how to get this done. If you can e-mail me at vincent.king.miller@us.army.mil with an e-mail I can attach a file to I will send what I can so you can help me if you can.

Thanks.
Vince

February 27, 2012 at 10:37 AM  
Blogger pevensies said...

Hello Darrel;
I am new to the Cisco world working on my CCNA. I purchase several items from Cisco Kits, and have a network setup however I cannot get this network to communicate with the internet. I have look at (several times) your DHCP and NAT Podcast and tried to replicate the configuration at my home, however I still cannot get it to function. If I can send you my packet tracer file maybe you can tell me how to get this done. If you can e-mail me at vincent.king.miller@us.army.mil with an e-mail I can attach a file to I will send what I can so you can help me if you can.

Thanks.
Vince

February 27, 2012 at 10:38 AM  

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