First, let me say that this report is not an endorsement or condemnation of the @Home service. The report is intended to provide members of the Princeton University community with information and the experience of one member of the university's OIT staff. Any person considering @Home or any other Internet Service Provider (ISP) should understand how the ISP functions, the cost of the service, and their own needs and uses for Internet access. This report may be of value by helping members of the Princeton University community assess these issues.
The Comcast cable TV network services the area where my home is located. In October 1997 Comcast announced the availability of the @Home Internet service, an ISP providing high-speed Internet access. In my case, the Comcast Cable network provides part of the physical network connectivity (my home to the @Home network) and @Home provides the nation-wide network infrastructure with connectivity to the Internet. In addition, @Home provides "value added" services such as Email and webpage hosting. @Home also provides value added content by having a website accessible only to @Home subscribers. More information is available on the @Home public page and the general Comcast website, with specifics on the service of @Home via Comcast.
I am a subscriber to Comcast for cable TV service and had received an announcement (in my monthly cable TV bill) of the availablity of @Home service. I had intended to order the service for evaluation, but about a month after the announcement, I received a telephone call from Comcast offering me the @Home service with some "special rates." The normal installation charge is $150 and the special rate was $49.95. Other special offers existed such as a month of free service for pre-paying for one year, but I did not opt for this offer. As part of the telephone interview I was able to schedule the @Home installation. I was asked a number of questions about my home computer's configuration to insure it was powerful enough, had the required memory and disk space, and was of an acceptable type. The first available appointment was about two weeks later.
The machine being used for the @Home connection was a Dell 466/ME (a 486 system). I wanted to install Windows 95 (the machine had been running Windows 3.1). A SCSI adapter and CD-ROM were added to aid in the installation of Windows 95 and other software. An Ethernet board was part of the machine's original configuration. After Windows 95 was installed, the operation of the system was tested by being attached to the campus network. This was done to insure a fully functional and operational system before the @Home changes were made. I moved the machine to my home a few days before the @Home folks were scheduled to install the service. Once the Dell was installed at home, I was able, by using the remote access services (PPP) which are part of Windows 95 to connect via dial-in to the campus network. This provided me another method of gaining network access in case problems developed with the @Home service.
My installation was scheduled for 9am and at the appointed time two technicians arrived, one from Comcast and one from @Home. I already had cable TV service in the room where the computer lives so no additional cable service needed to be installed. The Comcast technician checked the physical cable for proper configuration and found some work was needed to replace some small cable devices (splitters) which had been used to distribute TV service within the house (the cable TV had been installed 10 years earlier). This was a simple matter, but required the Comcast technician to gain access to the cable TV wiring in the basement. In the meantime, the @Home technician started work on the PC. @Home will install an Ethernet board and required network software as part of the installation, but because I already had an Ethernet board and network software installed, this step was skipped. There is no extra charge if the Ethernet board is supplied by @Home, but no credit is given if you already have one.
The Comcast technician finished his work in about 30 minutes.
The @Home technician installed the "cable modem," a Motorola Cybersurfer unit which provides an Ethernet attachment (RJ45 twisted pair) and a coax connection to the cable TV network. This unit makes the physical connection of computer to network. In addition, Netscape Communicator 4 was installed (with a bunch of plug-ins) to provide Web and Email access. Because @Home is an ISP, your machine gets a network (IP) address on the @Home network and you get an email identity on the @Home network such as jsmith@home.net. The normal configuration is to connect one home computer to the cable modem. I did not investigate how multiple home machines would be attached to the @Home network.
The @Home technician, after completing the software installation and configuration (most of the software was downloaded over the network because he had forgotten to bring a copy of the CD-ROM), gave me a quick run through of the operation of Netscape 4 and the @Home and Comcast websites. Once the installation is complete, you are asked to call an 888 telephone number and supply a credit card which will be used to bill the installation and monthly charges. You will also receive a copy of the bills via Email to your @Home id. The @Home install process took a little over an hour to complete.
The Dell system I'm using is a 486 with 32M memory, 250MB hard disk, Ethernet board, Windows 95, Netscape 3 and some other applications such as TN3270. After the @Home software installation (Netscape Communicator 4), about 30MBs of hardisk space remained. During the @Home installation process, some of the audio files were deleted because the Dell does not have a sound board. You will need about 150MBs of free disk space for the @Home software installation.
After the technicians left, I ran a number of standard network tests to assure myself that the service was operational and able to provide connectivity to the Princeton campus network. None of the tests between my @Home system and the campus network detected any problems. A longer test was to do a complete backup of the hard disk via ADSM, an "over the net" centralized file backup system available to the members of the Princeton University community. The backup of all files (about 150MBs) took just about 1 hour to complete over the @Home network.
To date, I've had the service operational for several weeks. The physical connectivity appears to be reliable. The only problem I've experienced is that the Netscape 4 client is somewhat unstable. It fails to come up sometimes which requires a reboot of Windows, and sometimes it fails while in operation which necessitates starting it again. A new version appears to exist of the @Home software which includes Netscape Communicator 4, but I need more disk space (about 100M) to install the @Home package and I'm waiting for a JAZ drive to arrive.
The speed of the @Home connection is asymmetric: it has different data rates for data going from the PC to the network, and from the network to the PC. The material which comes with the service does not give specifics on the speed of the connection. It says things like "the cable modem communicates with your computer at Ethernet speed." I have reviewed the specifications of the Motorola cable modem. From what I have been able to learn and observe, the cable modem can transmit at a rate of 768Kbs and my throughput measurements would indicate a rate transfer rate of 600Kbs+, so these numbers appear correct.
The rate in the other direction (network to PC) is higher. The available literature is very non-specific and the reason for this is that the bandwidth, in this direction, is shared amongst a group of subscribers. My tests from the Princeton campus network to an @Home connected computer indicate a transfer rate of 1.5MBs. In general, these data rates provide performance which, for most applications, feels the same as being connected to the campus network.
These numbers may not mean much to you, so let me try to compare these rates with dial modem and ISDN rates to help give you a better sense of throughput speeds. A current dial modem (v.34) can operate at 28.8Kbs (28,800 bits per second). An ISDN channel is 64Kbs (64,000 bits per second). Both of these services tend to be symetric, that is, operating at the same speed in both directions (computer-to-network and network-to-computer). The @Home computer-to-network rate is 768Kbs (768,000 bits per second) and the network-to-computer is about 1.5Mbs (1,500,000 bits per second). Or, another way of looking at this is that the @Home connectivity is 25-50 times faster than a dial modem and 12-23 times faster that an ISDN channel. This is based on the transport speeds and does not take into account data compression or packet overhead. This comparison is an attempt to present a rough "feel" for the different technologies.
The PC-to-@Home network connection is via Ethernet, because Ethernet is a shared network medium concerns exist about unauthorized viewing of network data. The cable modem uses a data encryption scheme for information flowing over the cable TV network. This means that your cable modem receives only its data. You can not see your neighbors' data nor can they see yours. The encryption covers communication between your home and the @Home equipment in your cable TV provider's central location. Once the data enters the Internet, it is no longer encrypted. For more information on the modems data encryption, check the specifications for the Motorola Cybersurfer modem.
The @Home service, like all Internet Service Providers, transports only IP packets. This affects people who may be using non-IP services such as Novell and Appletalk. These non-IP protocols do not function over the Internet without special software and configurations on both the client and campus sides. The technique used is called "tunnelling". Tunnelling permits non-IP protocols to be transported over the Internet by wrapping these packets in IP packets. At the other end of the tunnel (the Princeton campus for example), the IP wrapper is removed and the packet is forwarded to the campus network. Details have not yet been worked out as to what software components are needed to create a tunnel for access to campus Novell servers. No work is currently under way to support tunnelling of AppleTalk. Some AppleTalk software may exist, but we would need to understand what services (printing, file sharing, ...) users want to access to be able to evaluate the usability of these products.
Here are some items which you may wish to consider when getting the service installed which may aid the installation process:
I was able to unplug the Ethernet connection and use my dial-in modem to connect to the University network. Using the modem allows access to the Novell servers because IPX is supported by the dial-in communication server.
In general, the @Home service appears to be stable (except for the Netscape client) and provides improved throughput when compared to dial-in modem or ISDN services.
I've installed the JAZ drive on the Dell without any problem. A CD-ROM version of the @Home/Comcast software came in the mail (not asked for, just arrived). With the extra disk space, I was able to download the latest version of the @Home software, but the downloaded version is 1.2 which is what I already have installed. So, I need to wait for a new update to see if the Netscape problems are resolved.
The service continues to be stable and perform well.
Peter Olenick
Princeton University - OIT
polenick@Princeton.EDU