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How ISPs May Quietly Kill VoIP
ravenII writes "PBS's i'Cringley's informative piece gives an eye-opening look at the anticompetitive behavior of some ISPs who are showing up late to the VoIP game. This is not something that could be easily mandated, and the beauty of this approach is that they're not explicitly doing anything to the 3rd party service applications. They're just identifying and tagging their own services, which is within their rights."
Read the damn article, this is different to the case you mention. They are not blocking access to other VoIP providers. However they are tagging (or will?) be tagging their own VoIP traffic which will force all other VoIP provider's traffic to run as non-guaranteed traffic and thus, could lead to dropouts or all round crap service.
...and just as you can tunnel just about any traffic you want through port 443 assuming you know what you're doing, you can encrypt traffic between networks. Granted, that will make things more difficult at first, but it will allow people to get around things like this.
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Actually, adding on another layer of encryption makes the problem worse. From the article summary:
"...the beauty of this approach is that they're not explicitly doing anything to the 3rd party service applications. They're just identifying and tagging their own services, which is within their rights."
The service providers are prioritizing THEIR VoIP traffic; so unless you can encrypt and then mask your VoIP service provider's packets to look like the ISP's, all encryption will do is increase the latency for voice - remember encryption/decryption requires time. The ISP doesn't explicitily delay Vonage's packets, for example, it simply upgrades the QoS priority of their own packets; this conveniently screws over 3rd-party providers like Vonage while not getting the ISP's in legal hot water.
Encryption can protect your 3rd party call from evesdropping, but can only increase latency under this new sneaky scheme.
Well, you've got the idea correct, but it has nothing to do with how DSL can run aside POTS. DSL can run along POTS because one uses the low frequencies, and the other uses the high frequencies. If you have DSL on your phone line, and don't have the filter, you'll likely hear a hissing, that's the DSL signal.
However, should you get a combination cable modem/MTA (the VoIP box) from you cable operator (i.e. Comcast), it works like this:
* The DOCSIS 1.1 specification calls for a nifty little feature called "service flows". Service flows have their own QoS, and can be triggered by a variety of criteria, including TCP/UDP port numbers, Ethernet frame type, etc.
* From there, the cable operators will provision two (or more) service flows for the cable modem. One would be for the voice, which would receive the highest priority possible (but with a lower bandwidth), and the other one(s) would be best-effort, with a higher bandwidth allowed.
Cable operators can also use this to throttle any arbitrary connection (i.e. P2P), and in fact, have done so in the past, I would imagine.
A "side effect" of this would be that Vonage boxes would considered as best-effort, simply because they don't get classified into the voice flow by the software of the modem. This is because they won't meet the characteristics of the voice flow.
-- Joe
you're thinking of "chaos" not "anarchy"... do some reading.
But fundamentally, the things Cringely's complaining about aren't accurate, because he doesn't understand the technology or the resulting economics. Yes, telcos are dealing with the threat of VOIP, and it's making their heads explode, and VOIP is much *much* harder to integrate with an old-fashioned telephone infrastructure than to run as a pure-VOIP business. (The technology's difficult, making it scale is difficult, different parts are centralized or decentralized, all the assumptions about who hands money to whom are different, the regulatory infrastructure doesn't match well at all, etc.) And the telcos are making sure that their data networks will support any VOIP services they develop with as close as they can get to traditional telco voice quality, and they're not sure how to deal with the fact that cellphones have convinced the public to accept lower-quality calls and newer codecs with much higher frequencies can support speakerphones much better.
Some big ISPs happen to be owned by telcos, or by telco-wannabees like the cable TV companies. Most of them are working on adding CoS capabilities to their backbones, but that's the least critical part of the network because most of them own their own fiber plants, and it's cheaper for them to burn more wavelengths on their fibers than to add fancy engineering capabilities to their routers or to hire fancy engineers to run them. It's the friendly mom&pop ISPs (that Cringely's not worried about) who are most likely to have backbone congestion issues that need CoS support to prioritize VOIP over best-effort data applications, because they're running at a different scale and don't generally own their own fiber networks.
The places that CoS matters most are the skinny parts of the network - the ingress from the customer's premises to the ISP's POP, and the egress from the ISP's POP to the customer's premises. The ingress direction is really a customer hardware and management problem, making sure that VOIP packets get on the wire before data packets, but service providers (including Vonage) typically handle that by forcing the customer's data through the same box that converts traditional-phone signals to VOIP, and software-based providers like Skype handle that inside the user's PC. This doesn't require the ISP to do anything, though it's sometimes cheaper to build those capabilities into the DSL/cable modem.
The egress direction can benefit from CoS marking, or from other fair-queuing systems that share bandwidth between remote sites or protocol types, or even from dumber systems that prioritize UDP over TCP. In a symmetric environment, like most business T1 connections, this is the most critical part of the system, because data applications can drown out voice unless there's some QoS approach. But most consumer connections are asymmetric, with much faster downstream connections than upstream, so there's less of a problem. Also, in most home applications, if downstream bandwidth is the bottleneck, it's usually because of some application like downloading music that can be turned off or slowed down during phone calls, which isn't a practical approach in most multi-person offices.
Cringely's arguments are especially bogus because the impact of backbone QoS / CoS features on network performance is much smaller than the impact of slow upstream connections in ADSL and Cable Modems. A 12
Bill Stewart
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There were mass settlements of Bulgars in the Apennines at various times trough the Middle Ages. There are a lot of Bulgarian toponyms in Italy, for example Monte Bulgheria. Bulgarian derived family names are common in some places - Bulgari and Borgii are famous examples. The Latin language itself was "vulgarized" due to a large number of non-native speakers (mostly Germanic people, like the Langobards).
"Vulgar" acquired a negative meaning later: plain, plebeian, unrefined, coarse and rude. It is quite a common linguistic phenomenon. Actually, in "Genealogy of Morals" Nietzsche claims that the words for "bad" in all languages have evolved likewise.
Way off-topic, I know. Whatever.