Cisco Nexus 7000 Series - Configuring AS-Path Lists

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16-8
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
OL-20002-02
Chapter 16 Configuring Route Policy Manager
Configuring Route Policy Manager
Configuring AS-path Lists
You can specify an AS-path list filter on both inbound and outbound BGP routes. Each filter is an access
list based on regular expressions. If the regular expression matches the representation of the AS-path
attribute of the route as an ASCII string, then the permit or deny condition applies.
SUMMARY STEPS
1. config t
2. ip as-path access-list name {deny | permit} expression
3. show {ip | ipv6} as-path list name
4. copy running-config startup-config
DETAILED STEPS
The following example shows how to create an AS-path list with two entries and apply the AS path list
to a BGP neighbor:
switch# config t
switch(config)# ip as-path access-list AllowAS permit 64510
switch(config)# ip as-path access-list AllowAS permit 64496
switch(config)# copy running-config startup-config
switch(config)# router bgp 65536:20
switch(config-router)# neighbor 192.0.2.1/16 remote-as 65535:20
switch(config-router-neighbor)# address-family ipv4 unicast
switch(config-router-neighbor-af)# filter-list AllowAS in
Command Purpose
Step 1
config t
Example:
switch# config t
switch(config)#
Enters configuration mode.
Step 2
ip as-path access-list name {deny |
permit}
expression
Example:
switch(config)# ip as-path access-list
Allow40 permit 40
Creates a BGP AS-path list using a regular expression.
Step 3
show {ip | ipv6} as-path-access-list
name
Example:
switch(config)# show ip
as-path-access-list Allow40
(Optional) Displays information about as-path access
lists.
Step 4
copy running-config startup-config
Example:
switch# copy running-config
startup-config
(Optional) Saves this configuration change.