Reference Guide

CONFIGURATION mode
ip as-path access-list as-path-name
2. Create a AS-PATH ACL filter with a deny or permit action.
AS-PATH ACL mode
{deny | permit} as-regular-expression
3. Return to CONFIGURATION mode.
AS-PATH ACL
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5. Filter routes based on the criteria in the configured route map.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} filter-list as-path-name {in | out}
Configure the following parameters:
• ip-address or peer-group-name: enter the neighbor’s IP address or the peer group’s name.
• as-path-name: enter the name of a configured AS-PATH ACL.
• in: apply the AS-PATH ACL map to inbound routes.
• out: apply the AS-PATH ACL to outbound routes.
To view which commands are configured, use the show config command in CONFIGURATION
ROUTER BGP mode and the show ip as-path-access-list command in EXEC Privilege mode.
To forward all routes not meeting the AS-PATH ACL criteria, include the permit .* filter in your AS-PATH
ACL.
Filtering BGP Routes
Filtering routes allows you to implement BGP policies.
You can use either IP prefix lists, route maps, AS-PATH ACLs or IP community lists (using a route map) to
control which routes the BGP neighbor or peer group accepts and advertises. Prefix lists filter routes
based on route and prefix length, while AS-Path ACLs filter routes based on the ASN. Route maps can
filter and set conditions, change attributes, and assign update policies.
NOTE: Dell Networking OS supports up to 255 characters in a set community statement inside a
route map.
NOTE: With Dell Networking OS, you can create inbound and outbound policies. Each of the
commands used for filtering has in and out parameters that you must apply. In Dell Networking
OS, the order of preference varies depending on whether the attributes are applied for inbound
updates or outbound updates.
For inbound and outbound updates the order of preference is:
• prefix lists (using the neighbor distribute-list command)
• AS-PATH ACLs (using the neighbor filter-list command)
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Border Gateway Protocol IPv4 (BGPv4)