BGP Interview Questions & Answers - Networkwalks Academy

BGP is which type of Routing Protocol?

BGP is a Path Vector Routing Protocol. It falls under the category of EGP (Exterior Gateway Protocol)

Which algorithm is used by BGP for best path selection?

BGP uses Composite Metric for best path selection and install the best routes into the routing table

What are BGP Path attributes?

BGP uses multiple attributes or metrics for best path selection which are Weight (cisco), LOCAL_PREF, aggregate, as_path, origin, MED, neighbor type (ebgp > ibgp), igp metric (next_hop), route age, router ID (originator ID), Neighbor IP

How many neighbor states are there in BGP ?

BGP has 6 neighbor states:

Idle, Connect, Active, OpenSent, OpenConfirm, Established

Which port is used by BGP for its communication?

BGP uses TCP Port 179

What is official standard of BGP?

Official standard RFC for BGP is IETF RFC4271 (BGPv4 – 2006)

Does BGP support authentication?

Yes, BGP supports MD5 authentication

How many packet types are there in BGP?

There are four types of packet in BGP:

Open, Update, Keepalive, Notification

What is the purpose of each type of BGP packet?

Open Message: Set up and establish BGP adjacency
Update Message: Advertise, update & withdraw routes
Keepalive Message: Ensure that BGP neighbors are still alive
Notification Message: Error Condition notification

What is BGP Origin Code?

The BGP Origin Code is one of the attribute that is used for path selection. There are three BGP origin codes called as IGP, EGP & Incomplete as in below: