5/8/98 Wirbel article. Internet Protocol gets rules for good behavior
By Loring Wirbel with additional reporting by Rick Boyd-Merritt
Posted: 11:45 p.m., EST, 5/8/98
pubs.cmpnet.com
ATLANTA - Now that it seems the Internet Protocol is
everywhere, designers of systems that span the gamut from cable
modems to wide-area network switches are finding it's time the
protocol actually grew up and became manageable. At the
NetWorld+Interop show in Las Vegas and at Cable '98 in Atlanta,
internetworking specialists and cable-TV operators hammered out
mechanisms to create controllable networks from a protocol
designed for connectionless traffic.
Powerful business interests in both public and private networks are
driving the demand for well-defined quality-of-service (QoS)
features for prioritizing IP flows in ways similar to what's possible
with connection-oriented asynchronous transfer mode (ATM). But
substantial engineering challenges still stand in the way.
In the private networking arena, "the most significant technical
trend I see is the application of policies, classes and qualities of
service to networking," said Daniel Pitt, director of the Bay
Architecture Lab at Bay Networks Inc. (Santa Clara, Calif.). "This
is how a company will translate its business needs into its systems.
But the industry has not made enough progress in translating
quality-of-service into realizable architectures and products."
Among service providers, "ISPs are desperate to find a way to
make more money," said Gordon Saussy, vice president of
marketing for Torrent Networking Technologies Corp. (Silver
Spring, Md.). "They need to find a way to sell first-class seats and
get out of the business of selling flat-rate services. Fine-grained
quality-of-service is their way to [do] that."
Rob Glaser, chief executive of RealNetworks Inc. (Seattle), made
QoS a central theme in his Thursday N+I keynote, boiling down
the issue to consumer expectations. Glaser noted that the new
RealSystem G2 Internet multimedia player will implement a new
smart streaming feature, which will scale down the player's
bandwidth and performance at times of network congestion rather
than halt video or audio streams when too many packets clog the
Net. He advised paying close attention to a new standard, the
Synchronized Multimedia Integration Language (SMIL), which he
called an HTML equivalent for linking multimedia objects to the
Real Time Streaming Protocol.
Since different network managers have different goals for QoS,
methods vary widely for assigning service classes to IP. Some
managers seek only to preserve mission-critical, time-sensitive
mainframe applications. Others want IP quality-of-service to
include explicit support for low-latency isochronous traffic, such as
voice and video.
Finding solutions to the former problem would bring network
managers a step closer to true policy-based network
configurations. The latter requirements would provide better
support for voice-over-IP, the holy grail among providers ranging
from competitive local-exchange carriers to cable-TV multi-system
operators. Solutions for Internet QoS range from the all-software
traffic shapers offered by CheckPoint Software Solutions Inc. to
the dedicated hardware offered by Packeteer Inc. and the totally
new architecture promoted by IP Highway Inc.
In any event, providing an efficient solution set for IP QoS
promises potentially big returns. Cisco Systems Inc. last week
acquired one such provider, Class Data Systems Inc. (Ra'anana,
Israel), for $50 million in Class B stock. And IP Highway, the
Israeli company's closest competitor, experienced some of the
heaviest traffic at N+I's Startup City.
Cisco plans to integrate the Class Data prioritizer into its own
Assure initiative for applications-based networking. First releases
of the integrated software will only handle mission-critical business
applications, though Cisco and Class both pledged eventual
support for isochronous services.
While Class Data has been exploring point solutions, newcomer IP
Highway (San Jose) has developed an end-to-end scheme based
on a new enterprise architecture. A QoS Management Server
oversees clusters of Policy Servers and QoS Generators. Policy
Servers sit at the edge of the WAN and determine enterprise
policy for handling traffic from outside. The QoS Generator is the
machine that actually assigns QoS parameters for IP flows.
IP Highway chief technical officer Shai Herzog said implementing
the topology would let end users keep all their legacy hardware
and software yet have traffic provisioned from the server with full
QoS signaling.
At Packeteer, developers are working to hardwire or provide in
firmware pre-standard QoS methods that are somewhat specific to
network topologies. Last week, Packeteer released an enterprise
version of the software for its bandwidth shaper, as well as a
version specific to Cisco networks. The latter leverages Cisco's
algorithms for tag switching, weighted fair queuing and weighted
random early detect.
The Packeteer software has also been made Java- and
object-module-aware. Marketing vice president Bob Quillin said
support for real-time services may be possible in the future but
called effective traffic shaping with non-real-time traffic the larger
challenge.
Designers also worry that work on quality-of-service could
mushroom into a new IP bottleneck. "One problem is how to
reduce or eliminate the amount of flow-by-flow state information in
the core of the network," said Bay's Pitt.
Since ATM began as a connection-oriented packet switching
standard based on identically sized cells, and it's ironic that
advocates of connectionless IP are embracing QoS concepts that
they once rejected in ATM as too complex. "QoS for IP can turn
IP into a protocol at least as complex as ATM," said Gary
Mading, market-development manager for ATM products for
Motorola Semiconductor Products Sector (Plano, Texas).
View from TV
Yet the National Cable Television Association's Cable '98 show
put out the call for advanced IP QoS parameters that would make
prioritization for voice, video, and data traffic over IP finer-grained
than the ATM equivalent. The standards efforts operate on at least
two levels in the Open System Interconnect protocol stack.
Broadcom Corp. (Irvine, Calif.) and Bay Networks (Billerica,
Mass.) have devised a packet-fragmentation scheme, operating on
the media-access-control (MAC) layer of a cable-modem design,
that will be incorporated into Release 1.1 of the Data Over Cable
System Interface Spec (Docsis) developed by Cable Labs.
Broadcom already supports the fragmentation features in a new
MAC device for cable modems. But marketing vice president Tim
Lindenfelser said that as a Docsis standard, the fragmentation
scheme will be open to any chip vendor wishing to implement it.
Ethernet packets can be split at the home interface into equally
sized cells of 16 kbytes to 256 kbytes, and various priorities can
be set for for variable, unspecified and best-effort bit rates. For
voice services' continuous-bit-rate traffic, the fragmentation scheme
assigns packets to what Broadcom calls a directed-grant service.
Gerry White, chief technical officer of Bay Networks' broadband
technology division, said the company was excited enough about
Broadcom's proposal to be a cosponsor for the Docsis specs. But
he added that Bay also saw a need for transport-layer mapping of
IP flows to packet fragments. It thus partnered with 3Com Corp.
and American Internet Inc. to promote a QoS Working Group
within the Multimedia Cable Network Systems group working on
Docsis. That group now is addressing network- and
transport-layer schemes for QoS mapping to the new
packet-signaling method.
LCP modems, too
Meanwhile, Bay Networks is taking its vision of enhanced IP
functions a step further by implementing voice-over-IP and
virtual-private-network (VPN) functions in the former LANcity's
LCP modems while adding centralized IP-security functions
through the Extranet switch, to which it gained access when it
acquired New Oak Communications Inc. late last year. While
telephony and Internet access groups are the first within Bay to
make use of the Extranet switch, White said, new members of the
family, such as Extranet 1000, are suited for use as front ends to
cable multi-system operators' headends. End-to-end networks can
be implemented using QoS over IP.
Advanced IP services played a role in several large cable-modem
contracts announced at the show. France Telecom will offer an
alternative to the character-based Minitel service through a
cable-modem infrastructure put together by Philips Broadband
Networks using modems from Com21 Inc. Buck Gee, vice
president of marketing at Com21, said the company will leverage
voice-compression cards and packetization schemes for
voice-over-IP to follow up its initial products for the France
Telecom contract with next-generation modems that will enable
more IP features.
Advanced IP service also factored into Tele-Communications Inc.
subsidiary TCI.Net's decision to award 3Com Corp., Bay
Networks Inc. and Thomson Electronics a contract to supply cable
modems for its Internet services. Rob Davenport, chief operating
officer, said TCI.Net wants to offer voice and video over IP by
summer 1999 and to add VPN-like features within a year after
that.
Similar motivations drove Shaw Communications (Calgary,
Alberta) to buy 40,000 modems and related headend equipment
from Terayon Corp. (Santa Clara, Calif.) and to make a $7.5
million equity stake in Terayon. |
