GTE's WorldWind: The real truth about their
service and how they do system-wide bandwidth throttling!
@Home: One of the major Cablemodem providers rolling out service across the US.
Bay Networks's (previously LanCity) Web page about their new 3rd generation equipment.
Motorola's CyberSURFR Cablemodem: Motorola has a a large marketshare of the current deployed enduser cablemodems. @Home uses them. Time Warner uses them.
The state of the Cablemodem industry: This excellent article from USA Today sheds light on the state of cablemodems and why the industry barely exists today (if ever). [An older article but still relivant]
Check out Bob's web page with bookmarks to other Cablemodem vendors.
Check out a new vendor to the cablemodem ranks: Terayon with funding from Cisco Systems
|ISDN vs. ADSL vs. Cable (4/1/98)||ISDN||ADSL||Cablemodems|
|Setup:||$125- Telco setup
$ 31 - Account Setup
$200- ISDN modem
|$125- Telco setup
$31- Account Setup
$350- ADSL modem
|$150- Cable setup
cablemodem rental part of monthly fee
|Monthly:||$31- ISDN dialtone
|$80- ADSL dialtone (384Kb/384Kb)
$80- ISP (DNAI)
|Total Cost:||Initial: $356
|Pros/Cons||Pro: cheaper, 2 voice lines, dedicated bandwidth, static IP, can choose
Con: Dial-up circuit, only 128Kb/s of bandwidth, only 140hrs left out of 160hrs per month (free), usage billed during business hours, no free local voice calls, if someone hogs your line from the Internet, your monthly bill will go through the roof!
|Pro: 384Kb/s dedicated link, Always up, static IP address, voice
service over same copper pair, can choose your ISP
Con: High cost, ADSL is in trial and service might go away or become more expensive
|Pro: 2Mb/s down -- 500Kb/s up, Always up, static IP address, setup
fee includes on-site setup, ISA or PCI 3Com NIC, and patch cable.
Con: No ISP choice, shared cable plant, single source for ISP
So.. As you can tell, it really is a no brainer in terms of cost and performance on paper. How does the @Home experience really work? Good. Not great though.
@Home is the cablemodem and networking arm of several different CableTV vendors including: CableVision, ComCast, COX, InterMedia, Marcus, and TCI. The @Home service in my area uses the Motorola CyberSURFR Cablemodem at the enduser's home and a HFC or Hybrid Fiber-Coax system for data connectivity back to the main node.
So far, connectivity has been pretty good but I've noticed a few things:
Latency (PING times) vary widely: I have noticed that this system has ping times at ~18ms within the local cablemodem system but usually the ping times to the Internet skyrockets up towards 200ms (Alter.net [BBN]). This SUCKS for any on-line gaming situations!
Connectivity pauses: Since getting the service, I have noticed that connectivity is initially slow. It seems that the Motorola hardware has two network queues:
Chambers Cable of Chico, CA is starting a commercially available cablemodem service for a relatively low cost. Though the system may seem initially like a good deal, there are several problems with their design that will make it ultimately fail until they upgrade their coax cable plant. Here are the facts as of November 1st, 1997:
|Chambers CableModem Contact:||Heidi @ 1-800-547-8921 or Chamber's WWW site|
|Monthly price:||$39.95 per month|
|Cable Modem Manufacturer and Part Number:||Scientific Atlanta #569150|
|Chico Cable Modem Vendors:||Compusell, Itworks|
|Cable Modem Price:||$299.00 (Ethernet NIC included)|
2) As usual, the Chico plant is a low priority for Chambers. See this press release on how Chambers is upgrading their other two coax plants but not Chico.
4) Most of all their system's in-line amplifiers are running at their maximum bandwidth (no room for more channels)
5) Chambers does not have enough network bandwidth to back haul the traffic
Chamber's coax backbone system doesn't have any redundancy nor the backbone capacity to handle more channels.
With the system I originally deployed, we were using a full 6Mhz channel for each direction yielding 10Mb/s for user's transmitted and received traffic. Their new system utilizes (2) 3Mhz channels [probably the same spectrum I was using before] for a maximum transmit rate of 6Mb/s per channel UNI-DIRECTIONAL ONLY.
How many users do you think it will take to saturate the (2)6Mb/s links when each enduser's machine is connected at 10Mb/s Ethernet speeds?
Last time I checked, Chamber's connection to the Internet was only a 384Kb/s Fractional T1 connection. Also, remember, this link is for their existing analog modem dial-up service too!
Ok, so lets be generous and say they have a upgraded it to a FULL T1. Still, a connection like this will be a major bottleneck for their new cablemodem customers.
For Chambers to offer a decent service level to their customers, they will need to implement at least (1) DS3 (45Mb/s) connection today and be prepared to get a a OC-3 (155Mb/s) or fractional OC-12 (622Mb/s) connection in the future. Don't count on Chambers even ordering a T3 (DS3) anytime soon!
Chamber's existing Cable service is known for crappy TV signal quality in Chico and their existing analog Dial-in modem Internet service has had it's problems too.
This style of cablemodem design is only good for the occasional internet surfer that downloads far more data than they upload. The reason for this is because the speed of this system limited to the cablemodem's analog modem port. Currently, this cablemodem's modem port supports v.34+ which can yield 33.6k in the best cases. I haven't heard any news of a 56k modem port (or upgrade) for the Scientific Atlanta cablemodem nor if Chambers will upgrade their modem pools to support 56Kb/s connections.
I haven't confirmed this yet but I'm pretty sure that since this system is modem-based, once you are off-line, you CANNOT contact your machine at home unless someone initiates a connect from your house. Most bi-directional cablemodems are on-line 100% of the time. Most likely, this is purely a firmware issue that could be implemented by Scientific Atlanta but I doubt Chambers would be inclined to enable this feature.
You will still need an extra modem line if you are going to be on-line all the time (~$16/month + $30 install)
You are required to purchase the Scientific Atlanta cablemodem before you can even get on-line. Since there are still NO standards for cablemodem systems and if you move away from Chico, you need to either sell the modem or become proud of your new $300 pet rock!
Beyond all of these issues, the real sad part of this new system is that doesn't come even close to the same performance and availability levels that my original system did. Why? Read the next section.
In Chico, Chambers Cable provides various television programming from channel 2 to, currently, channel 36. Cablemodems and other hardware made by LanCity Corporation, receive Internet traffic on an unused channel (37) and send Internet traffic back on channel (-2). If you would have tuned your TV to channel (37) when the pilot was active, you would have noticed the slightly moving horizontal lines. Between those two lines was network data traffic!
A little Background:
Each non-compressed television channel uses typically about 6Mhz [6 million signals per second] of bandwidth for both the video and audio signals. In contrast, a common analog telephone line uses only about 3.2Khz of bandwidth. So if you think your 28.8k modem is fast.. you haven't seen anything yet! Putting it very generically, the cablemodem is just like an analog modem using a MUCH larger bandwidth to transmit and receive data over a different connection.
Last Updated: 09/13/99