Concept Guide

• ip-address or ip-address or peer-group-name: enter the neighbor’s IPv4 or IPv6 address or the peer group’s name.
• as-path-name: enter the name of a congured AS-PATH ACL.
• in: apply the AS-PATH ACL map to inbound routes.
• out: apply the AS-PATH ACL to outbound routes.
Example conguration for ltering BGP routes using AS-PATH information
Following is the sample conguration for ltering BGP routes using AS-PATH information
DellEMC# configure terminal
DellEMC(conf)# ip as-path access-list 100 deny ^500$
DellEMC(conf)# ip as-path access-list 100 permit .*
DellEMC(conf)# router bgp 400
DellEMC(conf_router_bgp)# neighbor 10.10.10.1 remote-as 450
DellEMC(conf_router_bgp_af)# address-family ipv4 multicast
DellEMC(conf_router_bgp_af)# neighbor 10.10.10.2 filter-list 100 out
DellEMC(conf_router_bgp_af)# exit
In the above example, a BGP access list (100) is dened to deny any AS-path that starts and ends with 500 and permit all other routes.
The access list is applied for outgoing BGP routes for the neighbor (10.10.10.2) and the routes are ltered or distributed based on the
congured rules set in the access list.
To view which commands are congured, 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 .* lter in your AS-PATH ACL.
Conguring BGP Route Reectors
BGP route reectors are intended for ASs with a large mesh; they reduce the amount of BGP control trac.
NOTE
: Dell EMC Networking recommends not using multipath and add path simultaneously in a route reector.
With route reection congured properly, IBGP routers are not fully meshed within a cluster but all receive routing information.
Congure clusters of routers where one router is a concentration router and the others are clients who receive their updates from the
concentration router.
To congure a route reector, use the following commands.
• Assign a cluster ID or an IP address to a router reector cluster.
CONFIG-ROUTER-BGP mode
bgp cluster-id ip-address | number
– ip-address: IP address as the route reector cluster ID.
–
number: A route reector cluster ID as a number from 1 to 4294967295.
You can have multiple clusters in an AS. When a BGP cluster contains only one route reector, the cluster ID is the route reector’s
router ID. For redundancy, a BGP cluster may contain two or more route reectors. Without a cluster ID, the route reector cannot
recognize route updates from the other routes reector within the cluster.
• Congure the local router as a route reector and the specied neighbors or peer group as members of the cluster.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | ipv6-address | peer-group-name} route-reflector-client
When you enter this command for the rst time, the router congures as a route reector and the specied BGP neighbors congure as
clients in the route reector cluster. When you remove all clients of a route reector using the no neighbor route-reflector-
client command, the router no longer functions as a route reector. When you enable a route reector, Dell EMC Networking OS
BGP IP version 4 (BGPv4) Overview
221