=====BGP Fundamentals Lesson 1=====

  - BGP is a ++Answer|path-vector routing ++ protocol.
  - BGP message types:
    - OPEN
    - UPDATE
    - NOTIFICATION
    - ++Answer|KEEPALIVE ++
  - This BGP attribute ensure a loop-free path for routes. ++Answer|AS_PATH ++
  - For more scalability and configurability ++Answer|address++-family configuration is used.
  - AFI
    - Identifies the ++Answer|protocol ++
    - Correlates to a specific ++Answer|network ++ protocol such as: 
      - ++Answer|IPv4 ++
      - ++Answer|IPv6 ++
      - ++Answer|VPN, and so on ++
  - BGP Identifier

    * When the RID is changed, BGP sessions will reset and reestablish.
    - IOS Order of precedence:
      - ++Answer|Highest ++ IP address of the ++Answer|loopback ++ interfaces that are ++Answer|up ++.
      - ++Answer|Highest ++ IP address of the ++Answer|interfaces ++ that are ++Answer|up ++.
    - IOS-XR order of precedence:
      - ++Answer|Lowest ++ IP address of the ++Answer|loopback ++ interfaces that are ++Answer|up ++.
      - Otherwise, a value of ++Answer|0.0.0.0 ++ will be set and no neighborships will form.