Raunak Goyal
Roll -76,Secton -B
PGDIE 42
Summary of “Multicast Data
Transmission Using Distance Vector Multicast Routing Protocol
Delivering of packets from a single source (Sender) to a single
destination (Receiver) is called Unicast. In Unicast Communication,
relationship between the source and destination is One-to-One [3]. Here both
source and destination addresses in IP datagram are unicast addresses, assigned
to the hosts. Protocols providing Unicast communication is meant as Unicast
Protocols.
Communicating with all the hosts that can be called as
destinations using a single source (Sender) can be called as Broadcast
Communication. Here the relationship between the source and destination is
One-to-All [3]. Internet does not explicitly
support broadcasting because of huge amount of traffic it would create with
higher bandwidth. Imagine the traffic generated in the Internet if one person
wanted to send a message to everyone connected in the internet.
In networking, an emerging trend
evolves with the delivery of packets from one or more senders to a group of
receivers. This mechanism includes bulk data transfer, continuous media
streaming, updating web cache, data feeds and interactive gaming [9]. In these
applications, a process called multicast is used in extreme. Sending of a
packet from one source (Sender) to multiple destinations (Receivers) using a
single operation – send is called as Multicast Communication. Multicast
packets sent among hosts are the Multicast Groups. Multicast communication is
not a connection oriented. Multicast datagram is transmitted over the
destination group members that are reliable as unicast IP datagram.
Today‘s
challenging economy demands that enterprises leverage the value of their
current technology investments to increase productivity, while at the same time
decreases their operating costs. As a result, enterprises are beginning to
explore the benefits of sending single data to multiple destinations using
Internet Protocol (IP) based network that can deliver significant cost savings
and help to provide for enterprise continuity [9]. In computer networking,
multicast is the delivery of a message or information to a group of destination
computers simultaneously in a single transmission from the source creating
copies automatically in other network elements, such as routers, only when the
topology of the network requires it. IP multicast is a technique for
one-to-many communication over an IP infrastructure in a network. i.e., single
user to the multiple user of the assigned group. The main advantages of the
multicast distance vector routing protocol is that DVMRP is cheaper and cost
effective when compared to other alternatives for increasing LAN and WAN
capacities, Reduces the load on the sending server, which no longer supports
sequential or concurrent unicast sessions due to scalability factor. Gets rid
of network congestion that is caused by existing application. Using a single
send operation, the data‘s are sent and those sent data copies are delivered to
many receivers in several ways: One-to-All Unicast: Sender uses separate
unicast transport connection to each receiver [16]. Sender‘s transport layer is
duplicated and transmitted over each of the individual connections..
Explicit
Multicast: Router
involves replication and forwarding of data copies on the multiple links to
reach the receivers. It provides explicit multicast support in the network laye
DISTANCE VECTOR MULTICAST ROUTING PROTOCOL:
Unicast distance vector routing
is very simple; extending it to support multicast routing is complicated.
Multicast routing does not allow a router to send its routing table to its
neighbors. To accomplish this, the multicast distance vector algorithm uses a
process based on four decision-making strategies can improve the shortcomings
of the previous one. They are
Flooding
Reverse Path Forwarding(RPF)
Reverse Path Broadcasting(RPB)
Reverse Path
Multicasting(RPM)
a) Flooding: In flooding strategy each router sends the incoming
packet to the every interface except the one from which it was received.
Flooding accomplishes the first goal of multicasting i.e., every network with
active members receives not a multicast . Although, flooding is broadcast, not
a multicast, there is another problem: it creates loops. This will be overcome
by the next strategy.
b) Reverse Path Forwarding (RPF): RPF
is a modified flooding strategy. To prevent loops, only one copy is forwarded;
the other copies are dropped. In RPF, a router forwards only the copy that has
travelled the shortest path from the source the router. To find this copy, RPF
uses the unicast routing table. The router receives a packet and extracts the
source address( a unicast address). It consults its unicast routing table an
though it wants to send a packet to source address
c) Reverse Path Broadcasting
(RPB): RPF guarantees that each
network receives a copy of the multicast packet without formation of loops.
However, RPF does not guarantee that each network receives only one copy; a
network may receive two or more copies
d) Reverse Path Multicasting
(RPM): As you have noticed, RPB does
not multicast the packet, it broadcasts it. This is not efficient. To increase
efficiency, the multicast packet must reach only those networks that have
active members for broadcasting to multicasting; the protocol uses two procedures,
pruning and grafting.
IMPLEMENTATION
OF DISTANCE VECTOR ROUTING :
DVMRP can be termed as a ―broadcast
& prune‖ multicast routing protocol. It builds per-source group multicast
delivery trees by pruning (removing branches from) the source‘s truncated
broadcast tree. It performs Reverse Path Forwarding checks to determine when
multicast traffic should be forwarded to downstream interfaces [1, 9]. In this
way, source-rooted shortest path trees can be formed to reach all group members
from each source network of multicast traffic.
A performance analyzer is
introduced between the routers to analyze the 1) Separation of multicast
traffic with the measurement of its statistics, 2) Internal information of the
routers are estimated, 3) A specific structure of mapping is introduced between
multicast traffic and internal information estimated.
Analyzer finds the status of
the message that is survived along the network. It identifies the message
status and reports in two different states such as:
1) Prune Message: It searches the
multicast group addresses that are to be prune and analyses the valid and
invalid period of propagation, if finds an invalid period then the group
address involves the mechanism of Pruning.
2) Graft Messages: It searches the multicast group address where the
messages are to be grafted and also while analyzing the time period it becomes
valid period. Also the time period in pruning can be invalid.
PERFORMANCE ANALYSIS:
DVMRP provides a simple model
when compared to other multicast routing protocols by making a pure source
specific multicast distribution trees for deploying and troubleshooting [2,
17]. It uses a own topology mechanism by updating the routing table each time
for enhancing a secure and fast transmission of messages in a network.
Multicast routing maintains an efficient data transmission by calculating the
shortest path in the network whereas other routing algorithm may transmit the
message through the network without any subsequent path [13, 16]. DVMRP routing
table that are constructed in multicasting technique can be the enhanced part
of the forwarding table, in which it shows the specific delay of the
transmission. Routing table of each router are automatically updated and
deleted for each round or for each data transfers that could enable a
continuous task in the network. By introducing a performance analyzer in this
task, we could grasp that the traffic intensity of this multicast data
transmission using DVMRP is low. By analysis, only the valid period can be
noted in the whole traffic made in the network which would be 49.1% over the
monitored link.
An enhanced mechanism is
dedicated here to survive fit, in this fast changing world. Multicast data
transmission using distance vector multicast routing protocol has brought a
revolutionary change in the communication field. Routing table concept for
multicast data transmission makes an affordable communication in the network.
Delivery trees that are identified along the network can be efficient. Multicasting
is made effective using DVMRP procedure for enhancing a secure transmission of
data. Implementation of this mechanism can endure a cost effective, a reliable
and a responsible data transmission. Multicasting procedure can be implemented
in upcoming communication fields to make an effective action. Several
enhancements can be made along this routing protocol to make a useful
propagation. Multicasting using DVMRP is a humble work, which can be subjected
to further improvements. In future, this core model can be developed with some
enhancing software which would specify only a secure multicasting task in data
transmission and can be used in the development of Wide area networks.
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