EBGP Default Route Preference Value

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In Junos, the default route preference value for EBGP (External BGP) is 170.

Route preference is a numerical value assigned to a routing protocol or a static route, which indicates the trustworthiness or preference of a route. When there are multiple routes to the same destination in the routing table, the router uses the route preference value to select the best route to forward the traffic.

In Junos, the default route preference values are assigned as follows:

• Directly connected routes: 0
• Static routes: 5
• OSPF intra-area routes: 10
• OSPF inter-area routes: 20
• OSPF external routes: 150
• IBGP (Internal BGP) routes: 200
• EBGP (External BGP) routes: 170

The EBGP protocol is used to exchange routing information between different autonomous systems (AS) on the internet. By default, Junos assigns a route preference value of 170 to EBGP routes. This value is lower than the default value assigned to IBGP routes, which is 200. Therefore, in a scenario where there are multiple routes to the same destination, the router will prefer EBGP routes over IBGP routes.

It's important to note that the default route preference values can be changed using the "preference" configuration option in Junos. However, it is generally recommended to keep the default values unless there is a specific need to change them.