How do I set local preferences in BGP?

How do I set local preferences in BGP?

BGP Local preferences can be applied in 2 ways –

1. R3(config)# ip prefix-list net4 4.4.4.0/24.
2. R3(config)# route-map PREF permit 10.
3. R3(config-route-map)# match ip address prefix-list net4.
4. R3(config-route-map)# set local-preference 300.
5. R3(config)# router bgp 1.
6. R3(config)# neighbour 192.168.35.5 route-map PREF in.

What is BGP default local preference?

The BGP local preference attribute is the second BGP attribute and is used to choose the exit path for an autonomous system. The local preference has to be set inbound on routes being received to influence the outbound routing behaviour. A higher local preference is preferred and the default is 100.

What is BGP no-export community?

The no-export BGP community is defined in RFC 1997: “All routes received carrying a [BGP] communities attribute containing this value MUST NOT be advertised outside a BGP confederation boundary” (i.e. outside our own AS, or across regular EBGP sessions).

What is a community in BGP?

What Is a BGP Community? A BGP community is an optional, transitive BGP attribute that is recognized and passed to other BGP peers. You might see a BGP community as a tag attached to the BGP routes exchanged between two BGP peers.

What is the use of local preference BGP?

You can use local preference to configure your autonomous system to select a certain exit point. Instead of configuring weight on each router you can use local preference because it is exchanged on all internal BGP routers. By increasing the local preference to 800 we can make AS 1 send all traffic towards AS 2.

What is default local preference?

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 are the well known communities of the BGP community attribute?

Here are the 4 well known BGP communities:

• Internet: advertise the prefix to all BGP neighbors.
• No-Advertise: don’t advertise the prefix to any BGP neighbors.
• No-Export: don’t advertise the prefix to any eBGP neighbors.
• Local-AS: don’t advertise the prefix outside of the sub-AS (this one is used for BGP confederations).

What is BGP Med?

MED (or metric) is the sixth BGP attribute: MED can be used to advertise to your neighbors how they should enter your AS. MED is exchanged between autonomous systems. The lowest MED is the preferred path. MED is propagated to all routers within the neighbor AS but not passed along any other autonomous systems.

How do I get rid of BGP community?

Step-by-Step Procedure

1. Configure the interfaces. [edit interfaces]
2. Configure BGP. Apply the import policy to the BGP peering session with Device R2.
3. Configure the routing policy that deletes communities.
4. Configure the autonomous system (AS) number and the router ID.

Why do we need BGP synchronization?

BGP synchronization is an old rule from the days where we didn’t run IBGP on all routers within a transit AS. The routers within AS2 are configured with OSPF, this is required since R2/R4 have to be able to reach each other to establish the IBGP session.