by July 4, 2009 0 comments



10G has been around for a long time, and finally we are starting to see
implementations of 10G in data centers. However with bandwidth hogging
applications on the rise, such as cloud computing, IP TV, Video on demand, etc,
most telcos around the world are starting to upgrade their backbone to 40G and
some have even begin testing 100G. Some of you might recall news on Verizon
Business doing a successful trial of 100G optical service with JANET, a UK
National Research and Education Network. IEEE has released a draft IEEE P802.3ba
for both both 40G and 100G. Let’s see what it contains.

IEEE P802.3ba
IEEE P802.3ba draft has specified a single architecture for both 100G and 40G
Ethernet. Other than increase in data rates to 100G and 40G, there will be no
other change at the MAC layer, which means characterstics such as frame size and
format, full duplex operation will be the same as in the previous architecture.

A PHY device connects MAC layer to the media. This device has a PMD, PMA and
a PCS sublayer. PCS or physical coding sublayer is responsible for encoding and
decoding of data bits into code groups and vice-versa from PMA. It also ensures
clock transition density along with transportation of control signals and frame
delineation. Also PCS uses the same coding scheme 64B/66B as used in 10G. PMA
(Physical Medium Attachment) sublayer performs functions such as reception,
trnamission, clock recovery and connects PCS with PMD sublayer. The draft also
defines a common physical interface PPI (Parallel Physical Interface) for both
40G and 100G with the only difference being the number of lanes supported.

Each lane in PPI operates at 10 gigabit per second, so incase of 40G, there
will be four transmit and four receive lanes, similarly for 100G there will be
10 transmit lanes and a smaller number of recieve lanes of 10 gigabits per
second. The final version of the standard is expected by 2010. More details
about the standard can be found at http://www. ieee802. org/3/ba.

Source: ethernetalliance.org

PLC
The long talked about technology PLC or Power line communication has finally
become a reality. As the name shows, PLC technology uses electric power lines
for transmitting digital data. Since electric voltage and data signals waves
operate at different frequences, there is no interference between them. This
technology uses Wavelet-OFDM modulation and the maximum data trasmission claimed
is upto 210Mbps. Currently this has been used largely to build smart homes. Just
like most new network technologies, PLC initially did not have any standard and
various PLC devices faced serious issues when communicating with each other. In
Dec 2008, IEEE has released IEEE P1901 draft for Power line communications which
defines medium access control and specifications of physical layer.

DIGILINK’s Plans
for Next-Gen Networks
Shridhar Kadam, Vice President – Product
Management. DIGILINK

1)What is the state of adoption of 10G by enterprises in India?
10G is widely accepted as a backbone technology and is currently used to
connect the core switches to the distribution/access switches. Server
connections on 10G are also positioned in the high end data centers of major
enterprises and animation studios. For the last few years, per port prices
of such switches have drastically reduced making them the best choice for
such applications.

2) Standards for 40G and 100G are expected to be finalized by next
year. How do you see this space evolve ?

Early adoption would be by the service providers and data centers as was the
case with 10G. Enterprise are sure to follow suit.

3) What is DIGILINK doing in this space?
DIGILINK is already positioning its 10G passive product line for enterprises
with a guarantee for future upgrades to 40G/100G performance. For active
products, currently we are marketing the Brocade switch range which supports
10G today and have the option of 40G & 100G upgrades. We are keenly watching
the developments on these technologies in the US and would like to be a
leading provider of these technologies to enterprises.

According to IEEE, this is to create a new standard for high speed (>100 Mbps
at the physical layer) communication devices via AC power lines, called
Broadband over Power Line (BPL) devices. IEEE claims this standard will use
transmission frequencies below 100 Mhz and will be usable by all classes of BPL
devices, including BPL devices used for the first-mile/last-mile connection
(<1500 m to the premises) to broadband services as well as BPL devices used in
buildings for LAN and other data distribution networks(<100m between devices).
More details about this can be found at www.hd-plc.org or http://grouper.
ieee.org/groups/ 1901/

Fixed-Mobile Convergence
In FMC there are a few options available for enterprises such as PBX-centric,
IMS-VCC, Unlicensed Mobile Access (UMA) etc. UMA allows carriers to provide
mobile services over WiFi networks as defined by 3rd Generation Mobile Group
(3GPP). With UMA users having UMA-enabled dual-mode cellular/Wi-Fi mobile
handsets, they can roam as well as easily handover between wireless and cellular
networks.

In a PBX-centric model, when a user’s mobile comes within the range of
enterprise WiFi, VoIP or PBX-centric client software on the user mobile, it will
automatically connect to PBX, and the mobile acts as the client of enterprise
PBX and incoming calls shall automatically be directed to the user’s
mobile.

Another framework getting pouplar for Fixed-Mobile Convergence is IMS-VCC
(IP-Multimedia Subsystem-Voice Call Continuty), which is defined under 3GPP
release 7. It provides usage of a phone number or a SIP identity between
cellular and WLAN.

The advantage of this system is that it can work with most cellular
technologies such as GSM, CDMA and UMTS. It also supports seamless integration
with VoIP networks.

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