CONFIG prefix-list
Router (config) #ip prefix-list list-name seq permit/deny network/len ge/le
Prefix-list was originally designed for BGP. The network address part and mask portion of the routing entry can be matched
IP prefix-list NAME Permit 172.16.0.0/22 ge le 24
/22: prefix 22bit the same
Ge24: Mask range min. 24 bits
Le24: Mask range Max 24 bits
When there is no GE, the mask range is the smallest and the prefix is the same
When there is GE, there is no Le, le=32
When there is no ge,le. GE and Le are the same prefix
IP prefix-list A Permit 0.0.0.0/0 GE 32//All host routes
IP prefix-list B Permit 128.0.0.0/2 GE16//All class B subnets
IP prefix-list C Permit 0.0.0.0/0 le 32//All routes
IP prefix-list D Permit 0.0.0.0/0//default route
IP prefix-list E Permit 0.0.0.0/1 no more than 24-bit subnets in the Le//a class
IP prefix-list A Permit 10.0.0.0/8 le32//a class private network address
IP prefix-list B Permit 172.16.0.0/12 le32//b class private network address
IP prefix-list C Permit 192.168.0.0/16 le32//c class private network address
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Outbound route filtering ORF
Role:
-Used to reduce unnecessary BGP traffic and CPU usage
-Router bar into the direction of the filter configuration Exchange to the neighbor router in the out direction to do
-The ORF message is encapsulated in the route refresh, negotiated in the open message
When the AS1 has 100 routes, and AS2 only need 10, at this time, AS2 can be configured Orf,filter-list to AS1, AS1 only to AS2 required 10
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Configuration: Nei x.x.x.x capability ORF prefix-list Send/receive/both
Router BGP 100
address-family IPv4 Unicast
Nei 172.16.1.2 Remot 200
Nei 172.16.1.2 ebgp-multihop
Nei 172.16.1.2 capability ORF prefix-list send
IP prefix-list FILTER seq Permit 192.168.1.10/24
Show Neighbor show ip bgp nei x.x.x.x//can see capabilities
Experiment
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。 AS200 Configuration Federation, r2r3=as2000. r4=as300
R5 Open 3 loopback 5.1.1.1; 5.1.1.2; 5.1.1.1.3
Demand. AS100 only requires 5.1.1.1 routing.
R1:
IP prefix-list test deny 5.1.1.2/31 le32
IP prefix-list Test permit 0.0.0.0/0 GE 32
Router BGP 100
Nei 12.1.1.2 prefix-list Test in
Sho IP bgp//can only see 5.1.1.1 routes
R2:
Sho ip bgp neighbor 12.1.1.1 advertised-routes//view R2 pass to R1 route
You can see that 3 5.1.1.x routes have been sent
R1:
Router BGP 100
Nei 12.1.1.2 capability ORF Prefix-list both
R2:
Router BGP 2000
Nei 12.1.1.1 capability ORF Prefix-list both
Sho IP bgp nei 12.1.1.1 AD//Can see only one route to R1
The ORF type of Cisco only supports Prefix-list
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Aspath-list Filtration
Local Configuration As-path access-list
Router (config) #
IP as-path access-list number permit/deny regexp
Neighbor Configuration Filter-list
Rotuer (Config-router) #
Neighbor Ip-address Filter-list As-path-filter in/out
Using regular expression matching
| : Represents or, | The two ends match any one
[]: denotes one within the range, [1234] [1-4]
. : Represents any one character [1-3]. [A]---213 and 3 spaces 3
^: Indicates the start of a string
$: Represents the end of a string
_: Represents any delimiter (cannot represent a number)
(): Represents a combination in which the result of the combination is then involved in a large expression
\: Is the caret character, that is, the original meaning of the special symbol in the following character is restored
*: 0 or more
? : 0 Live One
+: One live multiple
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CCIE Learning Note 4---BGP prefix list; Aspath-list