RoutingPrinciples - Revision history

130.126.24.216: /* Count-to-Infinity Problem */

2005-07-18T07:10:22Z

Count-to-Infinity Problem

← Older revision		Revision as of 07:10, 18 July 2005
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	Example:		Example:
	Router B looses link to A (and sets the local routing table entry for A to infinity),		Router B looses link to A (and sets the local routing table entry for A to infinity),
	but C still thinks it has a route to A over B. C propagates this to B and B believes		but C still thinks it has a route to A over B. C propagates this to B and B believes
	it can reach A over C. B now adds its delay to A to the received value and saves the		it can reach A over C. B now adds its delay to C to the received value and saves the
	new (believed) connection to its routing table (because it is smaller than infinity),		new (believed) connection to its routing table (because it is smaller than infinity),
	creating a loop between B and A for all messages sent to C. Step by step A and B now		creating a loop between B and C for all messages sent to A. Step by step B and C now
	update eachothers routing tables, increasing the entry for A each time until it reaches		update eachothers routing tables, increasing the entry for A each time until it reaches
	the value defined as infinity, causing the link to be recognized as broken.		the value defined as infinity, causing the link to be recognized as broken.

130.126.24.216: /* Count-to-Infinity Problem */

2005-07-18T06:46:25Z

Count-to-Infinity Problem

← Older revision		Revision as of 06:46, 18 July 2005
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	Router B looses link to A (and sets the local routing table entry for A to infinity),		Router B looses link to A (and sets the local routing table entry for A to infinity),
	but C still thinks it has a route to A over B. C propagates this to B and B believes		but C still thinks it has a route to A over B. C propagates this to B and B believes
	it can reach A over C. B now adds its delay to C to the received value and saves the		it can reach A over C. B now adds its delay to A to the received value and saves the
	new (believed) connection to its routing table (because it is smaller than infinity),		new (believed) connection to its routing table (because it is smaller than infinity),
	creating a loop between B and C for all messages sent to A. Step by step B and C now		creating a loop between B and A for all messages sent to C. Step by step A and B now
	update eachothers routing tables, increasing the entry for A each time until it reaches		update eachothers routing tables, increasing the entry for A each time until it reaches
	the value defined as infinity, causing the link to be recognized as broken.		the value defined as infinity, causing the link to be recognized as broken.

130.126.143.153: /* Count-to-Infinity Problem */

2005-07-17T21:41:22Z

Count-to-Infinity Problem

← Older revision		Revision as of 21:41, 17 July 2005
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	Router B looses link to A (and sets the local routing table entry for A to infinity),		Router B looses link to A (and sets the local routing table entry for A to infinity),
	but C still thinks it has a route to A over B. C propagates this to B and B believes		but C still thinks it has a route to A over B. C propagates this to B and B believes
	it can reach A over B. B now adds its delay to C to the received value and saves the		it can reach A over C. B now adds its delay to C to the received value and saves the
	new (believed) connection to its routing table (because it is smaller than infinity),		new (believed) connection to its routing table (because it is smaller than infinity),
	creating a loop between B and C for all messages sent to A. Step by step B and C now		creating a loop between B and C for all messages sent to A. Step by step B and C now

24.119.10.106: /* Routing Table */

2005-04-12T04:44:58Z

Routing Table

← Older revision		Revision as of 04:44, 12 April 2005
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	=== Routing Table ===		=== Routing Table ===
	In ''DV'' each router maintains a '''routing table''' containing one entry for each router in the subnet. A router usually has many outgoing lines or connections (e.g. wireless) from which more than one may lead to the same target, but with different quality, speed, or whatever metric is used to distinguish the best connection. The routing table keeps an entry for each router in the subnet, telling what line to choose when addressing that router including an estimate of time or distance to that destination (metric).~~aasdf~~		In ''DV'' each router maintains a '''routing table''' containing one entry for each router in the subnet. A router usually has many outgoing lines or connections (e.g. wireless) from which more than one may lead to the same target, but with different quality, speed, or whatever metric is used to distinguish the best connection. The routing table keeps an entry for each router in the subnet, telling what line to choose when addressing that router including an estimate of time or distance to that destination (metric).

	=== Distributing Routing Knowledge ===		=== Distributing Routing Knowledge ===

24.119.10.106: /* Routing Table */

2005-04-12T04:44:09Z

Routing Table

← Older revision		Revision as of 04:44, 12 April 2005
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	=== Routing Table ===		=== Routing Table ===
	In ''DV'' each router maintains a '''routing table''' containing one entry for each router in the subnet. A router usually has many outgoing lines or connections (e.g. wireless) from which more than one may lead to the same target, but with different quality, speed, or whatever metric is used to distinguish the best connection. The routing table keeps an entry for each router in the subnet, telling what line to choose when addressing that router including an estimate of time or distance to that destination (metric).		In ''DV'' each router maintains a '''routing table''' containing one entry for each router in the subnet. A router usually has many outgoing lines or connections (e.g. wireless) from which more than one may lead to the same target, but with different quality, speed, or whatever metric is used to distinguish the best connection. The routing table keeps an entry for each router in the subnet, telling what line to choose when addressing that router including an estimate of time or distance to that destination (metric).aasdf

	=== Distributing Routing Knowledge ===		=== Distributing Routing Knowledge ===

Jon at 13:55, 15 January 2005

2005-01-15T13:55:04Z

← Older revision		Revision as of 13:55, 15 January 2005
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	Many objectives lead to different routing mechanisms serving different ranges of application. This article will discuss the routing principles, the basic protocols, which are basis for many other optimized and specific protocols.		Many objectives lead to different routing mechanisms serving different ranges of application. This article will discuss the routing principles, the basic protocols, which are basis for many other optimized and specific protocols.

	While ''Distance Vector'' and ''Link State Routing'' serve to show these principles, you will find more detail on special Ad-Hoc Network oriented routing protocols in the [[RoutingProtocols\|Routing Protocols]] article.		While ''Distance Vector'' and ''Link State Routing'' serve to show these principles, you will find more detail on special [[Ad-Hoc Networks\|Ad-Hoc Network]] oriented routing protocols in the [[RoutingProtocols\|Routing Protocols]] article.

	== Distance Vector Routing (DV) ==		== Distance Vector Routing (DV) ==

Jon at 13:51, 15 January 2005

2005-01-15T13:51:36Z

← Older revision		Revision as of 13:51, 15 January 2005
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	Routing is the process of determining a message path from source to target (which are not directly connected) using multiple other hosts in the middle. Low level network communication is usually point to point and does know routing. Therefor higher level protocols need to be established -- routing protocols.		Routing is the process of determining a message path from source to target (which are not directly connected) using multiple other hosts in the middle to forward the message. Low level network communication is usually point to point and does know routing. Therefor higher level protocols need to be established -- routing protocols.

	Many objectives lead to different routing mechanisms serving different ranges of application. This article will discuss the routing principles, the basic protocols, which are basis for many other optimized and specific protocols.		Many objectives lead to different routing mechanisms serving different ranges of application. This article will discuss the routing principles, the basic protocols, which are basis for many other optimized and specific protocols.

Jon: /* Overview */

2005-01-15T13:45:12Z

Overview

← Older revision		Revision as of 13:45, 15 January 2005
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	=== Overview ===		=== Overview ===
	''Link State Routing'' is not like DV based on local knowledge, but on measuring and distributing the complete topology ~~first~~. The Dijkstra shortest path algorithm finally helps to determine the best routes through the subnet. And this is how it's done:		''Link State Routing'' is not like DV based on local knowledge, but on measuring and distributing the complete topology before routing data. The Dijkstra shortest path algorithm finally helps to determine the best routes through the subnet. And this is how it's done:
	# discover neighbors/learn network addresses		# discover neighbors/learn network addresses
	# measure delay/cost to each neighbor		# measure delay/cost to each neighbor

Jon: /* Literature */

2005-01-13T22:07:24Z

Literature

← Older revision		Revision as of 22:07, 13 January 2005
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	== Literature ==		== Literature ==
	* Andrew S. Tanenbaum "Computer Networks"		* [http://www.prenhall.com/academic/product?ISBN=0130661023 Andrew S. Tanenbaum "Computer Networks"] ISBN 0-13-066102-3
	* [[http://sar.informatik.hu-berlin.de/teaching/2004-w%20Ad-Hoc%20Networks/presentations/050-RoutingPrinciples.pdf\|Lecture Slides]]		* [http://sar.informatik.hu-berlin.de/teaching/2004-w%20Ad-Hoc%20Networks/presentations/050-RoutingPrinciples.pdf Lecture Slides]

Jon: /* Literature */

2005-01-13T21:57:14Z

Literature

← Older revision		Revision as of 21:57, 13 January 2005
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	== Literature ==		== Literature ==
	* Andrew S. Tanenbaum "Computer Networks"		* Andrew S. Tanenbaum "Computer Networks"
	* [http://sar.informatik.hu-berlin.de/teaching/2004-w%20Ad-Hoc%20Networks/presentations/050-RoutingPrinciples.pdf\|Lecture Slides]		* [[http://sar.informatik.hu-berlin.de/teaching/2004-w%20Ad-Hoc%20Networks/presentations/050-RoutingPrinciples.pdf\|Lecture Slides]]