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Define BGP AFI and SAFI in Brief

 AFI (Address Family Identifier):

  • AFI is a field in BGP that identifies the network layer protocol for which BGP is advertising routes.
  • It specifies the type of addresses being advertised, such as IPv4 or IPv6.
  • Examples of AFI values:
    • 1 for IPv4
    • 2 for IPv6

SAFI (Subsequent Address Family Identifier):

  • SAFI is a field in BGP that provides more specific information about the type of NLRI (Network Layer Reachability Information) being advertised within the AFI.
  • It defines how the addresses within the AFI should be treated, such as unicast, multicast, or VPN routes.
  • Examples of SAFI values:
    • 1 for Unicast
    • 2 for Multicast
    • 128 for MPLS-labeled VPN (VPNv4)

In Brief:

  • AFI tells which address family is being used (e.g., IPv4 or IPv6).
  • SAFI tells how the routes in that address family should be interpreted (e.g., unicast, multicast, or VPN).
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