BGP for CCIE Study Notes

BGP for CCIE Study Notes

Aggregate-Address Mask as-Set

Otherwise, the as-path information is lost when the route is aggregated.

R1 (config-router) # aggregate-address 1.0.0.0255.0.0.0 as-Set

Aggregate-Address Mask as-set advertise-maproute-Map-name

Use advertise-map to determine which as path information is always retained by aggregation.

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On R2:

1. Aggregate-address 10.1.1.0 255.255.255.0

R2:

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R1:

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R3:

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We can see that as information is lost. R1 and R3 can learn the summary route of 10.1.1.0/24, which originated from as2 of R2.

1. R2 (config-router) # aggregate-address 10.1.1.0 255.255.255.0 as-Set

R2:

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R1:

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R3:

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We can see that as information is saved ({1, 3}), R1 and R3 cannot learn the summary route of 10.1.1.0/24 (because it carries its own as number)

1. Only the as-path information of routes on R1 is retained during aggregation.

Access-List 1 permit 10.1.1.1

Route-mapclc permit 10

Matchip address 1

Aggregate-address 10.1.1.0 255.255.255.0 as-setadvertise-map CLC

R2:

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R1:

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R3:

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Because only the as-path information of the detailed route advertised by R1 is retained, R1 rejects the aggregation route, but R3 accepts the aggregation route, the following configuration achieves the same effect (retain the as-path information for the route advertised from the AS-path1 ):

R2 (config) # Ipas-path access-List 1 permit _ 1 $

R2 (config) # route-map aspath permit 10

R2 (config-route-map) # match as-Path 1

Aggregate-address 10.1.1.0 255.255.255.0 as-setadvertise-mapaspath

Aggregate-Address Mask route-map route-Map-nameaggregate-Address Mask Summary-only

Only publish aggregated routes after aggregation. No detailed routes are published by default)

Aggregate-Address Mask suppress-map route-Map-name

Suppress some detailed routes (detailed routes generated by permit are blocked)

BGP always-compare-med

Compare the med attributes of different

Bgpbestpath as-path ignore

Ignore as-path comparison during Routing

Bgpbestpath med Confed

Compares the med attributes of different federal states.

Bgpbestpath med missing-as-worst

If the learned route does not carry the med attribute (the announcement between different as nodes is not configured with route-map, but does not understand it in as), set the med to an infinite number.

BGP Confederation identifier as-number; BGP Confederation peersas-Numbers

For federated configuration commands, the first is required for each vro, and the second is required only for vrouters with different as federated neighbors.

BGP dampening half-life reuse suppressmax-suppress-time route-map route-Map-namebgp default local-preference

Default local-preference sent to the same as neighbor

BGP fast-external-fallover

When the interface is down and the neighbor's BGP session ends immediately, this command is used by default. If the interface is not down, the neighbor session will not end immediately. If the interface is shaken, no response will be sent.

R2 (config-router) # No BGP fast-external-fallover

Default-Information originate

Three steps are required to broadcast the default BGP Route to all neighbors:

1. Create a static default route: IP Route 0.0.0.00.0.0.0 fastethernet1/1 23.1.1.3

2. Re-publish the static route to BGP: R2 (config-router) # redistributestatic

3. Use the BGP command default-informationoriginate: R2 (config-router) # default-Information originate

On the advertised vro (note that the next hop is the next hop of the default static route ):

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Advertise the router's neighbors:

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Default-metric Metric

Specify the default re-release metric. If the default re-release to BGP is not specified, the metric is 0.

R2 (config-router) # default-metric 10

R2 (config-router) # redistribute staticmetric 20

Distance admin-distance IP-source-address IP-address-mask IP-access-list-Number

Modifies the Management Distance of an ACL-compliant route from a specified update source.

R2 (config-router) # distance 20 10.1.1.00.0.0.255 1

Maximum-path number-of-paths

R2 (config-router) # maximum-paths 2

Neighbor IP-address advertise-map route-map-name1non-exist-map route-map-name2

Advertise the route of the route-map-name2 to the neighbor, and advertise the route of the route-map-name1 if it does not exist

R2 (config-router) # Neighbor 1.1.1.1advertise-map map1 non-exist-map MAP2

Neighbor IP-address advertisement-interval seconds

Set the minimum interval for BGP Route updates. The default value of ibgp is 5 seconds and that of ebgp is 30 seconds.

R2 (config-router) # Neighbor 1.1.1.1advertisement-interval 10

Neighbor IP-address default-Originate route-maproute-Map-name

Declare a qualified default route to the specified neighbor (the BGP table of the router does not have this static route), with the condition that the route matched by route-map can be reached (exists in the IP route table ), declares that the router does not have a static default route. If there is no route-map, the router is declared unconditionally.

R2 (config-router) # Neighbor 12.1.1.1default-Originate route-map

Neighbor IP-address filter-list as-path-list-number in

Filter BGP routes that comply with the as-path-list

Neighbor IP-address Password

BGP Authentication

Neighbor IP-address remove-private-

Delete the private as number (64512 ~ 65535). Do not delete the update with the private as number, but delete the private as number in the as-path attribute for the outbound interface.

Neighbor IP-address prefix-list/route-MAP/AS-path-list/distribute-list namein/out

Filter route updates from/to a specified neighbor

Neighbor IP-address maximum-Prefix

Limit the number of prefixes learned from a specified neighbor

Neighbor IP-address Shutdown

Disable neighbor reply without deleting the BGP Configuration

Neighbor IP-address send-communityneighbor IP-address timers keepalive holdtime

The default survival time is 60 s, and the retention time is 180 s.

Network IP-Address Mask network-mask Backdoor

Change the Management Distance of the specified IP address learned from ebgp to 200 to make the ebgp link a backdoor.

Show ipbgp dampened-paths

This article is from the "flyclc" blog, please be sure to keep this source http://flyclc.blog.51cto.com/1385758/1539268