OSPF: Reference Bandwidth & Interface Bandwidth

[sanjaynetworklessons (Sanjaykumar M M)]

OSPF Unit 1: Chapter: Introduction to OSPF | Reference Bandwidth & Interface Bandwidth

I went through your video & Notes, i tried much, But I am not understanding,

1. What is Reference Bandwidth & Interface Bandwidth in OSPF?

let me tell you, correct me please if i am wrong.

As per my understanding:

Interface Bandwidth Means: Device/ Router Physical Interface Bandwidth. Isn’t it?
Ex: 1000Mb: Gig0/0, 100Mb: Fa0/0, 10Mb: Eth0/0. Am i rite?

Reference Bandwidth Means: It is the Link Bandwidth. Isn’t it?
Ex: Internet Link: 50Mbps, MPLS Link: 10Mbps, P2P Link:2Mbps, Leased Line: 40Mbps. Am i rite?

I dint understand the below sentence in the OSPF Chapter, Unit 1: Chapter: Introdcution to OSPF

The reference bandwidth is a default value on Cisco routers which is a 100Mbit interface. You divide the reference bandwidth by the bandwidth of the interface and you’ll get the cost.

Acc to you: what is reference bandwidth is a default value on Cisco routers*?

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Hope you would help me soon.

Thanks,
Sanjay