Telcos Break Internet-Traffic
Bottleneck
Bypass service to help divert calls generated by Web users away
from public switching telephone network
By Brian Riggs
Is Internet congestion slowing you down? Telcos such
as Southwestern Bell Corp. are busy exploring ways
to keep data traffic off the public switching telephone
network, which has become swamped with Internet traffic. By some estimates, Internet
use accounts for at least four times the amount of traffic generated by standard voice
calls.
Network managers whose dial-up users subscribe to Internet access services offered
over the telcos' networks can begin to expect faster connection times and possibly
faster throughput as a result of new services that bypass the public switching telephone
network (PSTN).
"What we are seeing with the Internet is four times the holding time," said Ken Heffner,
vice president and general manager of multimedia services at Northern
Telecommunications Inc.'s En-terprise Networks division in Richardson, Texas. "That
is completely screwing up the traffic parameters [of the PSTN]."
Bypassing the PSTN is ex-pected to be more appealing than previous tactics for
relieving congestion. For example, in response to the impact that Internet access has
had on their networks, some telcos have increased the number of switch ports available
for in-coming calls and have also re-quested that regulatory authorities require ISPs to
pay access fees for network use. Both of these approaches, however, result in costs
that will most likely be passed on to customers.
But Southwestern Bell is the first among many telcos to use Nortel equipment that lets
ISPs sell dial-up access services that completely bypass the PSTN.
Internet Access Fast Lane
The Internet/Intranet Transport Service (IITS) of Southwestern Bell is based on
Nortel's AccessNode switch interface, which has been installed in several of its offices.
AccessNode recognizes incoming calls by the number they originate from or users dial
in to. Voice calls are directed to telephone switches and the PSTN, whereas calls
placed to ISPs are directed to a Nortel Rapport Dialup Switch. The Rapport switch
acts as a modem bank by terminating modem calls before eventually sending them to
ISPs' frame-relay or ATM networks or to corporate LANs through the IETF's
(Internet Engineering Task Force's) proposed Layer 2 Forwarding (L2F) protocol.
Last month Internet America Inc., an ISP in Dallas, began offering Internet access
based on IITS to its customers in nearby Fort Worth. Other Southwestern ISPs, such
as Onramp Access Inc. in San Antonio, FlashNet Communications in Fort Worth, and
Southwestern Bell's Internet division, are planning to offer similar services in upcoming
months.
Bell Atlantic Corp. is among the other telcos working on services based on the Nortel
switch interface, but it has not yet committed itself to deploying them.
Everyone in the Internet access food chain benefits from PSTN bypass solutions such
as IITS.
Telcos free up ports on voice switches by keeping all digital traffic on digital networks.
Nortel estimates that deploying the Access-Node and Rapport switches costs telcos
about half the price of upgrading and maintaining the additional central-office phone
switches necessary to provide both Internet and voice services.
And dial-up modem users will see faster connection times to their ISPs. In addition,
throughput may be a bit faster because no digital-to-analog and analog-to-digital
translation is required, according to David Butler, chief technology officer at Internet
America.
ISPs such as Internet America that subscribe to the Southwestern Bell service don't
have to order, set up, and maintain modem pools because all pooling functions are now
handled by the telco.
Network managers in charge of large modem pools are also expected to see benefits
from IITS and comparable services, according to Butler.
Instead of supporting a bank of modems at a corporate site, managers can, in effect,
outsource their modem pools to telcos. Rather than dial in to the corporate modem
bank, users would dial in to the telco central office. All data would travel through the
AccessNode and Rapport switches at a telco's central office. It would then be sent to
corporate headquarters over a single high-speed line, such as ISDN Primary Rate
Interface (PRI), to a single low-end router.
In addition to reducing equipment costs associated with purchasing, maintaining, and
man-aging modem banks, this ap-proach would let managers support more remote
users over fewer WAN connections. For ex-ample, PRI lines can support a maximum
of 23 simultaneous connections. When terminating in a bank of 23 modems, only 23
dial-up users can use the equipment. But by subscribing to a service such as IITS,
managers can lease any number of ports on a modem bank managed by the telco.
Forty or more remote users could share a single PRI line, as long as they do not all dial
in at the same time.
Like all outsourcing endeavors, this PSTN bypass arrangement has its drawbacks.
Like the Texas ISPs subscribing to IITS, network managers will be completely
dependent on telcos for upgrading their modem technology. So as 56Kbps analog
modems and digital subscriber line technology begin to be deployed, telcos will have to
make the necessary upgrades before customers can benefit from them.
And industry watchers advise network managers not to expect all telcos to deploy
PSTN bypass services based on the Norteland Lucent Technologies Inc.equipment.
More PSTN Bypasses
Another way in which telcos are dealing with dial-tone congestion is with digital
subscriber line services. At the Internet World trade show last month in Los Angeles,
UUNET Technologies Inc. said that by July, more than two dozen cities in California
would have access to its Preferred Access 128 service. By the end of the fall,
UUNET's Internet digital subscriber line (IDSL) service is expected to be available in
more than 90 cities nationwide.
Because DSL connections link two modems--one at corporate locations, the other at
the telco central office--all traffic bypasses the telephone network.
UUNET's 128Kbps IDSL will cost $150 to $255 for local access, plus $750 a month
for Internet access, 20 point-of-presence E-mail accounts, 16 IP addresses, five
concurrent USENET news readers, and one domain name.
UUNET officials said the reason for the high price is that ISDL and an upcoming
768Kbps high-bit-rate DSL service are as much leased-line replacements as they are
ISDN alternatives. By comparison, a fractional T-1 (1.544Mbps) line averages
$2,000, not including customer-premises equipment costs. |
