Internetwork Design Guide -- Designing Large-Scale IP Internetworks - Revision history

Pzimmerm: added metadata

2012-10-16T21:21:08Z

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← Older revision		Revision as of 21:21, 16 October 2012
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		+	<meta name="keywords" content="internetworking, large scale"></meta>
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	This article focuses on the following design implications of the Enhanced Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF) protocols, and the Border Gateway Protocol (BGP):		This article focuses on the following design implications of the Enhanced Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF) protocols, and the Border Gateway Protocol (BGP):
	* [[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Network Topology\|Network Topology]]		* [[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Network Topology\|Network Topology]]

Rakelley2008: /* Figure: Aggregation example */

2012-05-24T06:47:46Z

Figure: Aggregation example

← Older revision		Revision as of 06:47, 24 May 2012
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	neighbor 3.3.3.3 remote-as 200		neighbor 3.3.3.3 remote-as 200
	neighbor 2.2.2.2 remote-as 100		neighbor 2.2.2.2 remote-as 100
-	network 160.10.0.0 aggregate-address 160.0.0.0 255.0.0.0 suppress-map CHECK	+	network 160.10.0.0
		+	aggregate-address 160.0.0.0 255.0.0.0 suppress-map CHECK
	!		!
-	route-map CHECK permit 10 match ip address 1	+	route-map CHECK permit 10
		+	match ip address 1
	!		!
	access-list 1 deny 160.20.0.0 0.0.255.255		access-list 1 deny 160.20.0.0 0.0.255.255
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	If you want the router to set the value of an attribute when it propagates the aggregate route, use an attribute map, as demonstrated by the following commands:		If you want the router to set the value of an attribute when it propagates the aggregate route, use an attribute map, as demonstrated by the following commands:

-	<pre> route-map SETORIGIN permit 10 set origin igp ! aggregate-address 160.0.0.0 255.0.0.0 attribute-map SETORIGIN </pre>	+	<pre>route-map SETORIGIN permit 10
		+	set origin igp
		+	!
		+	aggregate-address 160.0.0.0 255.0.0.0 attribute-map SETORIGIN </pre>

Rakelley2008: /* Figure: BGP peer groups */

2012-05-24T06:46:38Z

Figure: BGP peer groups

← Older revision		Revision as of 06:46, 24 May 2012
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	The preceding configuration defines the following policies for the internalmap peer group:		The preceding configuration defines the following policies for the internalmap peer group:

-	<pre> A route map named INTERNAL	+	<pre>A route map named INTERNAL
	A filter list for outgoing updates (filter list 1)		A filter list for outgoing updates (filter list 1)
	A filter list for incoming updates (filter list 2) </pre>		A filter list for incoming updates (filter list 2) </pre>

Rakelley2008: /* Figure: BGP peer groups */

2012-05-24T06:46:24Z

Figure: BGP peer groups

← Older revision		Revision as of 06:46, 24 May 2012
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	The preceding configuration defines the following policies for the internalmap peer group:		The preceding configuration defines the following policies for the internalmap peer group:

-	<pre>	+	<pre> A route map named INTERNAL
-	A route map named INTERNAL	+
	A filter list for outgoing updates (filter list 1)		A filter list for outgoing updates (filter list 1)
	A filter list for incoming updates (filter list 2) </pre>		A filter list for incoming updates (filter list 2) </pre>

Rakelley2008: /* Figure: BGP peer groups */

2012-05-24T06:45:59Z

Figure: BGP peer groups

← Older revision		Revision as of 06:45, 24 May 2012
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	The preceding configuration defines the following policies for the internalmap peer group:		The preceding configuration defines the following policies for the internalmap peer group:

-	<pre> A route map named INTERNAL	+	<pre>
-	A filter list for outgoing updates (filter list 1)	+	A route map named INTERNAL
-	A filter list for incoming updates (filter list 2) </pre>	+	A filter list for outgoing updates (filter list 1)
		+	A filter list for incoming updates (filter list 2) </pre>


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	neighbor 4.4.4.2 peer-group EXTERNALMAP		neighbor 4.4.4.2 peer-group EXTERNALMAP
	neighbor 1.1.1.2 remote-as 200		neighbor 1.1.1.2 remote-as 200
-	neighbor 1.1.1.2 peer-group EXTERNALMAP n	+	neighbor 1.1.1.2 peer-group EXTERNALMAP
-	~~eighbor~~ 1.1.1.2 filter-list 3 in </pre>	+	neighbor 1.1.1.2 filter-list 3 in </pre>

	In the preceding configuration, the '''neighbor remote-as router''' configuration commands are placed outside of the '''neighbor peer-group router''' configuration commands because different external ASs have to be defined. Also note that this configuration defines filter list 3, which can be used to override configuration options for incoming updates from the neighbor at IP address 1.1.1.2 (Router B).		In the preceding configuration, the '''neighbor remote-as router''' configuration commands are placed outside of the '''neighbor peer-group router''' configuration commands because different external ASs have to be defined. Also note that this configuration defines filter list 3, which can be used to override configuration options for incoming updates from the neighbor at IP address 1.1.1.2 (Router B).

Rakelley2008: /* Figure: Community filtering */

2012-05-24T06:44:59Z

Figure: Community filtering

← Older revision		Revision as of 06:44, 24 May 2012
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	!		!
	route-map check-community permit 10		route-map check-community permit 10
-	match community 1 set weight 20	+	match community 1
		+	set weight 20
	!		!
	route-map check-community permit 20		route-map check-community permit 20
-	match community 2 exact set weight 10	+	match community 2 exact
		+	set weight 10
	!		!
	route-map check-community permit 30		route-map check-community permit 30
	match community 3		match community 3
	!		!
-	ip community-list 1 permit 100 i	+	ip community-list 1 permit 100
-	p community-list 2 permit 200	+	ip community-list 2 permit 200
	ip community-list 3 permit internet </pre>		ip community-list 3 permit internet </pre>

Rakelley2008: /* Figure: Community filtering */

2012-05-24T06:44:10Z

Figure: Community filtering

← Older revision		Revision as of 06:44, 24 May 2012
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	neighbor 3.3.3.1 remote-as 300		neighbor 3.3.3.1 remote-as 300
	neighbor 3.3.3.1 send-community		neighbor 3.3.3.1 send-community
-	neighbor 3.3.3.1	+	neighbor 3.3.3.1 route-map SETCOMMUNITY out
-	route-map SETCOMMUNITY out	+
	!		!
	route-map SETCOMMUNITY permit 10		route-map SETCOMMUNITY permit 10
	match ip address 2		match ip address 2
-	set community 100 200 additive	+	set community 100 200 additive
		+	!
	route-map SETCOMMUNITY permit 20		route-map SETCOMMUNITY permit 20
	!		!

Rakelley2008: /* Figure: Community filtering */

2012-05-24T06:43:41Z

Figure: Community filtering

← Older revision		Revision as of 06:43, 24 May 2012
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	neighbor 3.3.3.1 remote-as 300		neighbor 3.3.3.1 remote-as 300
	neighbor 3.3.3.1 send-community		neighbor 3.3.3.1 send-community
-	neighbor 3.3.3.1	+	neighbor 3.3.3.1 route-map SETCOMMUNITY out
-	route-map SETCOMMUNITY out	+
	!		!
	route-map SETCOMMUNITY permit 10		route-map SETCOMMUNITY permit 10
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	ip community-list 3 permit internet </pre>		ip community-list 3 permit internet </pre>

-	In the preceding configuration, any route that has 100 in its community attribute matches community list 1 and has its weight set to 20. Any route whose community attribute is only 200 (by virtue of the exact keyword) matches community list 2 and has its weight set to 10. In the last community list (list 3), the use of the internet keyword permits all other updates without changing the value of an attribute. (The internet keyword specifies all routes because all routes are members of the Internet community.)	+	In the preceding configuration, any route that has 100 in its community attribute matches community list 1 and has its weight set to 20. Any route whose community attribute is only 200 (by virtue of the exact keyword) matches community list 2 and has its weight set to 10. In the last community list (list 3), the use of the internet keyword permits all other updates without changing the value of an attribute. (The internet keyword specifies all routes because all routes are members of the Internet community.)
		+
	==== BGP Peer Groups ====		==== BGP Peer Groups ====
	A BGP peer group is a group of BGP neighbors that share the same update policies. Update policies are usually set by route maps, distribution lists, and filter lists. Instead of defining the same policies for each individual neighbor, you define a peer group name and assign policies to the peer group.		A BGP peer group is a group of BGP neighbors that share the same update policies. Update policies are usually set by route maps, distribution lists, and filter lists. Instead of defining the same policies for each individual neighbor, you define a peer group name and assign policies to the peer group.

Rakelley2008: /* Figure: BGP route map filtering */

2012-05-24T06:43:13Z

Figure: BGP route map filtering

← Older revision		Revision as of 06:43, 24 May 2012
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	<pre>!Router C		<pre>!Router C
-	router bgp 300 network 170.10.0.0	+	router bgp 300
		+	network 170.10.0.0
	neighbor 3.3.3.3 remote-as 200		neighbor 3.3.3.3 remote-as 200
	neighbor 3.3.3.3 route-map STAMP in		neighbor 3.3.3.3 route-map STAMP in
	!		!
-	route-map STAMP permit 10 match as-path 1	+	route-map STAMP permit 10
		+	match as-path 1
	set weight 20		set weight 20
	!		!
	ip as-path access-list 1 permit ^200$ </pre>		ip as-path access-list 1 permit ^200$ </pre>

-	In the preceding configuration, access list 1 permits any update whose AS_path attribute begins with 200 and ends with 200 (that is, access list 1 permits updates that originate in AS 200). The weight attribute of the permitted updates is set to 20. All other updates are denied and dropped.	+	In the preceding configuration, access list 1 permits any update whose AS_path attribute begins with 200 and ends with 200 (that is, access list 1 permits updates that originate in AS 200). The weight attribute of the permitted updates is set to 20. All other updates are denied and dropped.

	==== Community Filtering ====		==== Community Filtering ====

Rakelley2008: /* Figure: MED example */

2012-05-24T06:41:47Z

Figure: MED example

← Older revision		Revision as of 06:41, 24 May 2012
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	neighbor 3.3.3.3 remote-as 300		neighbor 3.3.3.3 remote-as 300
	neighbor 4.4.4.3 remote-as 400		neighbor 4.4.4.3 remote-as 400
-	!Router B router bgp 400	+
		+	!Router B
		+	router bgp 400
	neighbor 4.4.4.4 remote-as 100		neighbor 4.4.4.4 remote-as 100
-	neighbor 4.4.4.4 route-map	+	neighbor 4.4.4.4 route-map SETMEDOUT out
-	SETMEDOUT out	+
	neighbor 5.5.5.4 remote-as 300		neighbor 5.5.5.4 remote-as 300
	!		!
-	route-map	+	route-map SETMEDOUT permit 10
-	SETMEDOUT permit 10	+	set metric 50
-	set metric 50	+
	!Router C		!Router C
	router bgp 300		router bgp 300
	neighbor 2.2.2.2 remote-as 100		neighbor 2.2.2.2 remote-as 100
-	neighbor 2.2.2.2 route-map	+	neighbor 2.2.2.2 route-map SETMEDOUT out
-	SETMEDOUT out	+
	neighbor 5.5.5.5 remote-as 400		neighbor 5.5.5.5 remote-as 400
	neighbor 1.1.1.2 remote-as 300		neighbor 1.1.1.2 remote-as 300
	!		!
-	route-map	+	route-map SETMEDOUT permit 10
-	SETMEDOUT permit 10 set metric 120	+	set metric 120
		+
	!Router D		!Router D
	router bgp 300		router bgp 300
	neighbor 3.3.3.2 remote-as 100		neighbor 3.3.3.2 remote-as 100
-	neighbor 3.3.3.2 route map	+	neighbor 3.3.3.2 route map SETMEDOUT out
-	SETMEDOUT out	+
	neighbor 1.1.1.1 remote-as 300		neighbor 1.1.1.1 remote-as 300
		+	!
	route-map SETMEDOUT permit 10		route-map SETMEDOUT permit 10
	set metric 200 </pre>		set metric 200 </pre>
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	ip route 160.10.0.0 255.255.0.0 null 0 </pre>		ip route 160.10.0.0 255.255.0.0 null 0 </pre>

-	The preceding configuration causes Router B to send out updates for 160.10.0.0 with a MED attribute of 50.	+	The preceding configuration causes Router B to send out updates for 160.10.0.0 with a MED attribute of 50.
		+
	==== Community Attribute ====		==== Community Attribute ====
	The community attribute provides a way of grouping destinations (called communities) to which routing decisions (such as acceptance, preference, and redistribution) can be applied. Route maps are used to set the community attribute. A few predefined communities are listed in[[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Table: Predefined Communities\|Table: Predefined Communities]][[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Table: BGP Administrative Distances\|Table: BGP Administrative Distances]].		The community attribute provides a way of grouping destinations (called communities) to which routing decisions (such as acceptance, preference, and redistribution) can be applied. Route maps are used to set the community attribute. A few predefined communities are listed in[[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Table: Predefined Communities\|Table: Predefined Communities]][[Internetwork Design Guide -- Designing Large-Scale IP Internetworks#Table: BGP Administrative Distances\|Table: BGP Administrative Distances]].