Dell S4048T-ON, Configuration Manual

Page: 215 / 1146

NOTE: Dell Networking OS supports up to 255 characters in a set community statement inside a route map.
NOTE: 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)
• route maps (using the
neighbor route-map
command)
Prior to filtering BGP routes, create the prefix list, AS-PATH ACL, or route map.
For configuration information about prefix lists, AS-PATH ACLs, and route maps, refer to Access Control Lists (ACLs) .
NOTE: When you configure a new set of BGP policies, to ensure the changes are made, always reset the neighbor or peer group
by using the
clear ip bgp
command in EXEC Privilege mode.
To filter routes using prefix lists, use the following commands.
1 Create a prefix list and assign it a name.
CONFIGURATION mode
ip prefix-list prefix-name
2 Create multiple prefix list filters with a deny or permit action.
CONFIG-PREFIX LIST mode
seq sequence-number {deny | permit} { any | ip-prefix [ge | le] }
•
ge
: minimum prefix length to be matched.
•
le
: maximum prefix length to me matched.
For information about configuring prefix lists, refer to Access Control Lists (ACLs) .
3 Return to CONFIGURATION mode.
CONFIG-PREFIX LIST mode
exit
4 Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5 Filter routes based on the criteria in the configured prefix list.
CONFIG-ROUTER-BGP mode
neighbor { ip-address | peer-group-name } distribute-list prefix-list-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.
•
prefix-list-name
: enter the name of a configured prefix list.
•
in
: apply the prefix list to inbound routes.
•
out
: apply the prefix list to outbound routes.
As a reminder, the following are rules concerning prefix lists:
• If the prefix list contains no filters, all routes are permitted.
Border Gateway Protocol IPv4 (BGPv4) 215