Route switching

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Route switching

The leg placement (Next Hop Forwarding) is a form of packet switching in the WAN .

In contrast to line switching , the packet switch does not know the whole way to the destination of the data packet , but only the route to the next 'intermediate station'. For this purpose, the packet switch has a routing table in which the relevant information is stored (see drawing). All destination addresses for which the first part is the same are forwarded to the same packet switch.

This form of data transmission is very effective, since the packet switch only ever has to evaluate the first part of the destination address and the source of the data is irrelevant for the forwarding. This source-independent routing makes the use of particularly efficient routing algorithms possible.

Forwarding algorithm

  • First, the destination address is evaluated,
  • then the corresponding entry is searched for in the routing table and
  • the packet is forwarded via the interface listed in the table.
  • If a packet reaches the intermediary to which the destination computer is connected, the second part of the address is evaluated,
  • the entry is searched for in the table and
  • the packet is forwarded via the appropriate interface.

The forwarding algorithm can be implemented very efficiently in the hardware.

literature

  • Peter Bocker: data transfer technology of data and text communication. Second edition, Springer Verlag, Berlin / Heidelberg 1983, ISBN 978-3-642-81973-5 .
  • K. Görgen, H. Koch, G. Schulze, B. Struif, K. Truöl: Basics of communication technology. Springer Verlag, Berlin / Heidelberg 1985, ISBN 978-3-642-70117-7 .
  • Helmut Kerner, Georg Bruckner: Computer networks. Springer Verlag, Vienna 1981, ISBN 978-3-211-81666-0 .
  • Peter Bocker: ISDN . Digital networks for voice, text, data, video and multimedia communications; 4th edition, Springer Verlag, Berlin / Heidelberg 1997, ISBN 978-3-642-64360-6 .
  • Fritz Krückeberg, Otto Spaniol (Hrsg.): Lexicon of computer science and communication technology. Springer Verlag, Berlin / Heidelberg 1997, ISBN 978-3-662-30400-6 .

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