MTNL is setting up two networks for the CWG 2010, out of which one ultra high
speed and state-of-the art network will be solely dedicated for the broadcast
applications. This network will provide high speed and multi-level redundant
connectivity to all venues and the IBC, while the core of the network shall be
at four MTNL exchanges across the city of New Delhi. The network has been
designed to have multiple levels of redundancy and no single point of failure
with respect to connectivity, fiber routes, exchange locations, network elements
(up to the card level of network elements) to ensure resilient and robust
operations. The link layer transport of the network will be done over dark
fibers of MTNL using router-integrated DWDM technology (ITU G.709 OTN) with
capacities of 10Gbps and 40Gbps transmission to support very high volume of HD
uncompressed video traffic.
The broadcast network for CWG 2010 will provide superior QoS and SLA to all
individual video flows over the network. While ITU recommendation for video SLA
are packet loss of the order of 10-6, max delay of 100-400ms and max jitter of
50ms; MTNL shall provide a video SLA from this network that shall have an order
of 10-8 or even better packet loss, 25-50ms of max delay and 1-5ms of jitter for
all video flows. Additionally, techniques such as light de-jitter buffer shall
be used on the HD Video Gateway at the IBC site to handover HD-SDI video to the
broadcasters that is practically jitter free.
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Jitendra Garg, DGM, ITS, CWG, MTNL |
One of the concerns that broadcasters may have is how video flows from venues
will travel to the IBC and whether multiple paths with deterministic diversity
shall be maintained to assure a resilient operation. MTNL will use a virtual
circuit (or tunnel) based technology in its network to provide multiple levels
of path to each video flow that are completely diverse over the network,
including venue node up to the card level, optical fiber path, exchange
diversity and IBC node up to the card level. The paths will be very
deterministic and shall always be working the way in which the administrator has
provisioned them in the network. Such deterministic path diversity will
guarantee no single point of shared elements in the network ensuring a very high
level of resiliency. Each of these virtual circuits (or tunnel) carrying a video
flow from venue to the studio shall have a guaranteed QoS & SLA with respect to
the delay, jitter, packet loss to meet the stringent requirements of the HD
uncompressed video contribution application. In case there is any failure on the
path of a virtual circuit, the video feed traversing that path shall not be
re-routed and will be dropped in the network itself at the point of failure.
This shall further ensure a deterministic performance and behavior of the
network to assure application SLA and prevent any issues from potential
oversubscription. The following figures represent a schematic of the multiple
paths with deterministic diversity for a multilateral flow from a critical venue
(such as JNS) to the IBC.
The use of carrier-class and state-of-the-art MPLS network ensures the
availability of multiple paths with deterministic diversity and at the same
time, it is also allowing MTNL to build a mesh network to offer multiple levels
of redundancy. For the multilateral flows at critical venues (JNS and IGSC) MTNL
will provide a three level redundancy (1+1+1+1) over four diverse paths, while
for all other venues two level redundancy (1+1+1) over three diverse paths shall
be provided to the multilateral feeds. For all unilateral feeds, one level
redundancy (1+1) over two diverse paths will be provided by MTNL. Legacy network
technology like SDH is only possible to be deployed in a ring topology that can
offer up to one level of redundancy over diverse paths (1+1); but the use of IP/MPLS
network is allowing MTNL to extend that capability to even three levels of
redundancy (1+1+1+1) over four diverse paths that will ensure better SLA for the
mission critical video contribution applications.
MTNL shall deliver a path breaking capability for the video contribution
flows in the CWG 2010 that is called 'live-live' video delivery over diverse
paths with lossless merge of the flows at the receiver video gateway. This
feature will provide hitless switchover within a live-live pair-a switchover
time of zero millisecond during a failure in the path like node failure/link
failure/fiber cuts/exchange failures.
The other challenge in dealing with HD uncompressed video contribution in a
large event like CWG 2010 is the network capacity as each HD uncompressed flow
requires in excess of 1.5Gbps of bandwidth from the network. Supporting multiple
such large flows requires the network to support next generation transmission
capacity like 40Gbps to ensure an optimal design. MTNL is using IP/MPLS next
generation network technology to build 40Gbps transmission links, since SDH
doesn't go beyond 10Gbps. This is allowing MTNL to build the optimal capacity in
the network without a requirement of putting multiple parallel networks to cover
up the bandwidth deficiencies of legacy technologies like SDH.
Video monitoring, service management and video delivery assurance are the key
attributes for an operator from a manageability perspective, since the operator
is delivering the service to its customers (broadcasters in this case) with a
SLA commitment. This aspect may not be important to the HB/RHBs, but it is
immensely important to MTNL since it has to be assured that services are running
with the right SLA. The proposed IP/MPLS network will enable MTNL to monitor the
service levels of the video flows on the network nodes (without putting any
extra hardware such as video probes) as the video passes them. This unique
capability of inline video monitoring is possible in network due to the IP/MPLS
technology that is application-aware and intelligent.
On the network level QoS and carrier class attributes, IP/MPLS has surpassed
SDH and has once again reset the 50ms benchmark in this area. Network
convergence due to component failures in SDH (like control card/line card) takes
50ms or more to recover; however, they take 0ms today on IP/MPLS allowing a
better SLA & more resilient operation.
Commitment
MTNL and its partners together will build and manage this network to deliver
broadcast contribution applications for CWG 2010. All organizations (MTNL &
partners) in this team are extremely confident and believe that the service
level-that will be provided from the proposed network-is way above the
expectations of the broadcasters. All organizations in this team are committed
to the grand success of CWG 2010 and this commitment comes right from MTNL, CMD
and its partner organization's CEO level. It will be ensured that the CWG 2010
broadcast network enables a great and successful show for video broadcasting.
Summary
For the broadcast network that is proposed for CWG 2010, MTNL has done all
due diligences before selecting the right technology that is most matured,
advanced and proven today; and shall deliver the SLA that would be beyond the
expectations of OC, HB and RHB. Top executives and the entire team of both MTNL
and its partners are fully committed to make the CWG 2010 broadcasting event a
grand success!
Jitendra Garg
The author is DGM, ITS, CWG, MTNL
vadmail@cybermedia.co.in
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