How does BGP detect local preferences?
BGP Local preferences can be applied in 2 ways –
- R3(config)# ip prefix-list net4 4.4.4.0/24.
- R3(config)# route-map PREF permit 10.
- R3(config-route-map)# match ip address prefix-list net4.
- R3(config-route-map)# set local-preference 300.
- R3(config)# router bgp 1.
- R3(config)# neighbour 192.168.35.5 route-map PREF in.
How do I filter BGP routes?
You can combine route maps with prefix lists to filter the routes advertised to or received from a BGP peer, to control routes redistributed into BGP, and to set BGP attributes for specific routes. Prefix lists alone can be applied to a neighbor to filter route updates.
Is higher or lower local preference better?
A higher local preference is preferred and the default is 100. The BGP Local Preference attribute or local-pref is used to influence the outbound routing decision of a router running BGP. It is the second attribute in the BGP best path algorithm with BGP Weight being the first.
How does local preference work?
The LOCAL_PREF (local preference) is the first attribute a Cisco router looks at to determine which route towards a certain destination is the “best” one and deserves a spot in the router’s routing table.
What does local preference mean?
local preference means the right or opportunity to select a person from an identified target group that is considered more desirable than another in a constituency, city, urban area or county; Sample 1.
What is the difference between prefix list and distribution list?
The most notable and important difference is that a prefix-list allows you to filter networks also based on their subnet mask. ACLs used in distribute list filter networks only by network addresses but they do not perform matching on subnet mask (in other words, for an ACL used in distribute list, the networks 192.0.
What is the default local preference BGP?
100
The default value for the local preference is 100. This also means that a route that has no local preference value is treated as if it had a local preference of 100.
What is the difference between weight and local preference in BGP?
You can use weight instead of local preference to influence the selected path to external BGP peers. The difference is that weight is configured locally and is not exchanged in BGP updates. On the other hand, the local preference attribute is exchanged between iBGP peers and is configured at the gateway router.
What is filter list in BGP?
A filter list is a form of route policy that restricts the routes that will be advertised or accepted based on the AS-Path of the route. To configure a filter list, you must first create an AS-path access list based on the known paths you wish to permit.