1. Subject Name: Computer Communication Networks Subject Code: 10EC71
Prepared By: Kala H S & Megha Gupta
Department: ECE
Date:
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2. Delivery, Forwarding, and Routing
UNIT - 7
Network Layer:
Delivery, Forwarding, and Routing
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3. TOPICS TO BE COVERED Delivery Forwarding Unicast Routing Protocols
Multicast Routing protocols
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4. Introduction
Delivery - the way a packet is handled by the underlying networks network layer. Forwarding - the way a packet is delivered to the next station. Routing - the way routing tables are created to help in forwarding. Routing protocols - continuously update - are consulted for forwarding and routing.
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5. DELIVERY
The network layer supervises the handling of the packets by the underlying physical networks. We define this handling as the delivery of a packet.
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6. FORWARDING
Forwarding means to place the packet in its route to its destination. Forwarding requires a host or a router to have a routing table. When a host has a packet to send or when a router has received a packet to be forwarded, it looks at this table to find the route to the final destination.
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7. Next-Hop Method Versus Route Method
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8. Network-Specific Method Versus Host-Specific Method
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9. Default Method
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10. Example 1
Make a routing table for router R1, using the configuration in figure below.
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11. Solution
Routing table for router R1
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12. UNICAST ROUTING PROTOCOLS
A routing table can be either static or dynamic. A static table is one with manual entries. A dynamic table is one that is updated automatically when there is a change somewhere in the Internet. A routing protocol is a combination of rules and procedures that lets routers in the Internet inform each other of changes.
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13. Intra- and Interdomain Routing
Example of Routing Protocols
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14. Distance vector routing tables
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15. Updating in distance vector routing
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16. Link state routing
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17. - In unicast communication, there is one source and one destination.
MULTICAST ROUTING PROTOCOLS
Unicasting
- In unicast communication, there is one source and one destination.
- A unicast packet starts from the source S1 and passes through routers to reach the destination D1.
- In unicasting, when a router receives a packet, it forwards the packet through only one of its interfaces (the one belonging to the optimum path) as defined in the routing table.
- The router may discard the packet if it cannot find the destination address in its routing table.
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18. Multicasting - One source & a group of destinations.
- The relationship is one-to-many.
- In this type of communication, the
source address is a unicast address,
but the destination address is a group address, which defines one or more
destinations.
- The group address identifies the members of the group.
- A multicast packet starts from the source S1 and goes to all destinations
that belong to group G1.
- In multicasting, when a router receives a packet, it may forward it
through several of its interfaces.
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19. Broadcasting
- In broadcast communication, the relationship between the
source and the destination is one-to-all.
- There is only one source, but all the other hosts are the
destinations.
- The Internet does not explicitly support broadcasting
because of the huge amount of traffic it would create and
because of the bandwidth it would need. Imagine the traffic
generated in the Internet if one person wanted to send a
message to everyone else connected to the Internet.
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20. Multicasting versus multiple unicasting
Multicasting starts with one single packet from the source that is duplicated by the routers. The destination address in each packet is the same for all duplicates. Note that only one single copy of the packet travels between any two routers.
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21. Multicasting versus multiple unicasting
In multiple unicasting, several packets start from the source. If there are five destinations, for example, the source sends five packets, each with a different unicast destination address. Note that there may be multiple copies traveling between two routers. For example, when a person sends an message to a group of people, this is multiple unicasting. The software creates replicas of the message, each with a different destination address and sends them one by one.
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22. Acknowledgement : MY SINCERE THANKS TO By Kala H S & Megha Gupta
THE AUTHOR PROF.BEHROUZ A FOROUZAN. BECAUSE THE ABOVE PRESENTATION MATERIALS ARE HEAVILY BORROWED FROM HIS TEXTBOOK “DATA COMMUNICATION & NETWORKING” 4TH EDITION, PUBLISHER TATA MCGRAW HILL
SURESHA V. PROFESSOR, DEPT. OF E&C, KVG COLLEGE OF ENGINEERING. SULLIA, D.K By
Kala H S & Megha Gupta
Assistant Professor
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