Triple Play Over SDH Unites the Traditional With the Modern

To be able to provide an infrastructure forinfrastructure, but also creates valuable
high-revenue broadband services like triple play,competitive advantages: Triple Play vendors are
operators are working feverishly to deployeager to get their services out into the
modern networks capable of supporting TV andmarketplace and they need to roll out a suitable
video streaming. But "pure-bred" next-generationnetwork infrastructure as quickly as they can.
networks with end-to-end IP infrastructure willEasy ConversionAs with many point-to-point
remain the exception in the foreseeable future.applications, simple conversion at the protocol level
Even in modern carrier networks, traditional linesis the most affordable means of carrying
will continue to play a role, and technologies likeEthernet traffic from the IP DSLAM across an
Ethernet over SDH are making it possible to buildSDH network. The IP DSLAM's Gigabit Ethernet
pragmatic solutions.interface is connected using a protocol converter.
With next generation networks (NGNs), carriersThis converts the Ethernet data into virtual
are deploying an Ethernet IP platform capable ofcontainers (VC-4) and transfers them across the
supporting not just services like Layer-2 VPNs,STM-1 interface directly to the network
VLANs, and voice over IP, but also video and TVoperator's add-drop multiplexer (ADM).
transmission. These networks consist of IPOne known issue associated with Ethernet over
MPLS-based transport networks andSDH is avoided here: the transportation of signals
Ethernet-based Metro networks. To reach theof variable length like Ethernet frames on
greatest possible number of customers, thesefixed-size units like virtual containers (VC) in SDH
networks support different types of access - onis anything but efficient. And the scale of Ethernet
DSL copper lines, cable TV lines and opticaltraffic (100 Mbps, 1,000 Mbps) does not fit the
Ethernet in the First Mile (EFM).hierarchy levels in SDH (around 150 Mbps with
Triple Play services - a combination of InternetSTM-1 and 450 Mbps with STM-3). Thus, the
access, telephony, TV and video - are expectedtransmission of traffic on a fully loaded Fast
to offer considerable sales potential in theEthernet interface over an STM-1 line would
consumer segment. Triple Play has plenty ofwaste one-third of the available bandwidth.
appeal for customers: they only need to pay forHere, however, the traffic from an only partially
one access service and can place phone callsloaded Gigabit Ethernet interface is transported on
affordably over the Internet, surf the Web,the STM-1 line, and the size of converter can be
watch TV, and access videos, games and musicchosen to best suit the actual data throughput. In
for their home entertainment platforms over thethe application example in the sidebar, an intelligent
network. These services can be offered on bothRIC-155GE Ethernet-over-SDH converter carries
DSL lines and back channel-enabled broadband TVGigabit Ethernet traffic with a maximum rate of
cable, so competition for consumer business willaround 150 Mbps from the IP DSLAMs across an
get tougher. DSL providers and TV cable networkSTM-1 line. This prevents bandwidth loss and
operators are suddenly finding that they are rivalseliminates the need for complex and costly
in the same market.solutions like virtual concatenation technology. If
There are, however, opportunities amid theadditional bandwidth is needed, equipment with an
competitive risks: Triple Play is seen as a meansSTM-4 interface can be deployed.
of increasing the average revenue per userThe name of RAD Data Communications' product
(ARPU), attracting new customers, and offsettingreveals plenty about the device: it is a rate and
shrinking margins in former cash-cow segments,interface converter with STM-1 (155 Mbps) and
like call charges and DSL access, with revenueGigabit Ethernet interfaces. The converter has a
streams from value-added services. So it's hardlynumber of additional functions, which make it
surprising that Internet service providers (ISPs)especially well suited for use in Triple Play-enabled
are working hard to begin offering attractivenetworks. It supports a large number of MAC
Triple Play services and to enrich these servicesaddresses and, therefore, a large number of DSL
with value-added communication capabilities andusers. In addition, when traffic is high the
entertainment content.converter can buffer data when it peaks. Using
But to deliver these services, ISPs need moreVLAN priority tagging, the device can also
than just a simple infrastructure for datadistinguish between applications - an important
transportation. They need modern networks thatcapability, particularly for the efficient transmission
are optimized for real-time applications, that canof TV channels (multicasts) on a network.
sustain the transmission of TV broadcasts andAt a glance
video on demand and enable guaranteed QualityThe requisite IP connectivity is not always on
of Service (QoS). This is good for carriershand to transport Ethernet data streams. One
because, with the decline in prices in recent years,way around this problem is to convert IP traffic
they can hardly turn a profit worth mentioning byinto SDH containers and to carry it on an SDH
simply providing data transport infrastructure.transport network. Bandwidth can be adjusted as
Modernization with IP DSLAMsTo support Triplenecessary, depending on the data rate.
Play services, the broadband infrastructure needsClosing gaps in IP networks
to be expanded. TV and video streams requireaffordablyTelefónica Germany is
much higher bit rates than, say, Internet accessexpanding its broadband infrastructure for
and VoIP applications. Because an individual videobusiness customers and Internet Service
stream today needs a transmission rate ofProviders (ISPs). Technology from RAD Data
between 1 Mbps and 4 Mbps (and this will increaseCommunications is being deployed to connect the
with the advent of tomorrow's new high-definitionEthernet infrastructure transparently using
TV formats), vendors need infrastructuresconventional leased lines: the RIC-155GE
capable of supporting rates of between 5 MbpsEthernet-over-SDH converter enables Gigabit
and 25 Mbps.Ethernet interfaces to connect up over SDH lines.
Furthermore, high Quality of Service is crucial toTelefónica Germany has a comprehensive,
Triple Play services because no one, for example,nationwide MPLS-based backbone. The company is
would be willing to put up with a jerky motion oncurrently building an unbundled Local Loop (LLP)
TV. So network operators are currently upgradingplatform. By the middle of this year, up to 40
their networks to support more demandingpercent of all households in Germany will be
services like IPTV (TV and video streaming overconnected. With this highly advanced,
Internet Protocol) and deliver them to theEthernet-based DSL infrastructure, service
customer on access technologies like ADSL2+.providers will be able to offer broadband services
This means that the local loop needs to belike ADSL2+ and, later, multimedia services like
modernized.Triple Play.
One key component in the new access networksMissing linkAround 1,600 IP-DSLAMs will be
are Internet Protocol DSL access multiplexers (IPconnected over Gigabit Ethernet lines to form
DSLAMs). These provide residential users with thering-structured Metro networks, mostly on dark
services on DSL lines and essentially form thefiber. However, fiber is not available at every
backbone of the Local Loop. The multiplexers areDSLAM location. Telefónica soon found a
connected to the network operator's IP, MPLS orsolution to close the gap: It leases SDH lines from
Ethernet transport infrastructures. Known asother network operators to carry its Ethernet
backhaul networks, these segments generally usetraffic. To be equipped to meet tomorrow's
packet-switched lines, with Ethernet being thedemands, the company was looking for an
connection of choice because of its simplicity.affordable product that would transparently
Unlike traditional DSLAMs, IP DSLAMs use IP orconvert the data traffic and support multicasts.
Ethernet rather than ATM. Besides the greater"When new services are rolled out, the issue is
data throughput and the need to carry videonot rapid time to market. If a company does not
streams smoothly, they also have to supporthave its own Ethernet or IP lines for DSLAM
voice traffic, in keeping with the principle of Triplebackhaul and if no dark fiber is available, SDH
Play. Equipment has to be capable of delivering thenetworks, which are still widely available, can
requisite high Quality of Service to sustain voiceprovide an answer," explains Ramon Horkany,
over IP and video real-time applications.Product Line Manager at RAD Data
Connecting the MultiplexersCommunications. "Leasing lines is often more
To connect an IP DSLAM, network operatorseconomical, particularly as the current price trend
generally use dark fiber and attach the equipmentis very favorable." Says Ingo Stampe, Director
to the fiber over Gigabit Ethernet. Optical fiber isNetworks with Telefónica in Germany, "Of
not available at every location, but instead ofall the solutions we looked at, RAD's RIC-155GE
installing new fiber in such cases, DSL networkconverter proved to be the most affordable
operators can rent conventional fixed SDH lines tooption for carrying Gigabit Ethernet interfaces
connect their multiplexers. This pragmaticover SDH lines."
approach is not just more economical, becauseTo download the PDF please visit RAD data
there is no need to deploy an all-fibercommunication site.