BGP Address Family

Introduction

There is a number of BGP address-families. Each one is identified by the Address-Family Identifier (AFI). Within each AFI there is a Subsequent Address Family Identifier.

AFI

  • Common AFI
  • From RFC2858 definition "This field carries the identity of the Network Layer protocol associated with the Network Address that follows. "
Value Description Notes
1 IPv4
2 IPv6

SAFI

  • Common SAFI:
  • From RFC2858 definition "This field provides additional information about the type of the Network Layer Reachability Information carried in the attribute."
Value Description Notes
1 Network Layer Reachability Information used for unicast forwarding
2 Network Layer Reachability Information used for multicast forwarding
4 Network Layer Reachability Information with Labels, using BGP to distribute labels
65 VPLS
70 BGP EVPN
128 MPLS-labeled VPN address
132 Route Target Constraint

Examples

  • 1/128 is VPNv4 Unicast MPLS
  • 2/1 is IPv6 unicast.

Additional Resources

IANA AFI
IANA SAFI

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