Address Family List under BGP Routing Protocol

 

Address Family List under BGP Routing Protocol

In BGP (Border Gateway Protocol), Address Family Identifiers (AFIs) and Subsequent Address Family Identifiers (SAFIs) are used to define the type of network layer reachability information being exchanged. These are typically configured under BGP routing protocol to support different types of routing information (like IPv4, IPv6, VPNv4, etc.).

Here's a list of commonly used AFI/SAFI combinations under BGP:


🔹 Common Address Family List (AFI / SAFI)

AFI (Address Family Identifier) SAFI (Subsequent Address Family Identifier) Meaning
1 (IPv4) 1 (Unicast) IPv4 unicast routing
1 2 (Multicast) IPv4 multicast routing
1 128 (MPLS-labeled VPN) VPNv4 (IPv4 MPLS VPN)
2 (IPv6) 1 (Unicast) IPv6 unicast routing
2 2 (Multicast) IPv6 multicast routing
2 128 (MPLS-labeled VPN) VPNv6 (IPv6 MPLS VPN)
25 (L2VPN) 70 (EVPN) Ethernet VPN (EVPN)
16388 128 (MPLS VPN) Route Target Constraint (RTC)
1 4 (Label) Labeled IPv4 unicast (for SR/MPLS)
2 4 (Label) Labeled IPv6 unicast
6 (NSAP) - CLNS/ISIS (not commonly used today)

🔸 Examples from CLI (Cisco-like syntax)

router bgp 65000
  address-family ipv4 unicast
    neighbor 1.1.1.1 activate
  exit-address-family

  address-family ipv6 unicast
    neighbor 2001:db8::1 activate
  exit-address-family

  address-family vpnv4
    neighbor 1.1.1.1 activate
    neighbor 1.1.1.1 send-community both
  exit-address-family

  address-family l2vpn evpn
    neighbor 2.2.2.2 activate
  exit-address-family

🔹 Notes:

  • VPNv4/v6 is used for MPLS Layer 3 VPNs.

  • EVPN (AFI 25 / SAFI 70) is widely used in modern data center fabrics (VXLAN/EVPN).

  • Labeled Unicast (SAFI 4) is relevant in Segment Routing (SR-MPLS).

  • RTC (AFI 16388) is used for filtering VPN routes using Route Targets.



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