DBN

MP-BGP Address Families

bgp mpbgp
Word count: 962Reading time: 6 min
2021/12/05

Today we will attempt to simplify understanding of the various MP-BGP types. We will discuss various acronyms, address families and modifiers.

Definitions

Acronym Phrase Usage
VRF Virtual routing and forwarding Multiple virtual routers with unique address space
MP-BGP Multiprotocol Extensions for BGP Allows for different types of address families to be distributed.
AFI Address Family Numbers ?
SAFI Subsequent Address Family Identifiers ?
NLRI Network Layer Reachability Information Destination information. For example, IP + mask.
RD Route Distinguisher Used to identify which VRF a route belongs.
RT Route Target BGP extended community attribute used to define import and exports.

Table

Address family

Number Description
1 IPv4
2 IPv6
11 IPX
12 AppleTalk
25 L2VPN

Cisco IOS:

1
2
3
4
5
6
7
8
9
(config-router)#address-family ?
  ipv4        Address family
  ipv6        Address family
  l2vpn       Address family
  link-state  Address family
  nsap        Address family
  rtfilter    Address family
  vpnv4       Address family
  vpnv6       Address family

Address Family Modifier

Number Description
1 Unicast (U)
2 Multicast
4 MPLS Labels (L)
65 VPLS
70 EVPN
128 MPLS VPN (L3VPN / VPN)
129 Multicast VPN

Cisco IPv4:

1
2
3
4
5
6
7
(config-router)#address-family ipv4 ?
  flowspec   Address Family modifier
  mdt        Address Family modifier
  multicast  Address Family modifier
  mvpn       Address Family modifier
  unicast    Address Family modifier
  vrf        Specify parameters for a VPN Routing/Forwarding instance

Cisco L2VPN:

1
2
3
(config-router)#address-family l2vpn ?
  evpn  Address Family modifier
  vpls  Address Family modifier

Cisco VPNv4:

1
2
3
4
(config-router)#address-family vpnv4 ?
  flowspec   Address Family modifier
  multicast  Address Family modifier
  unicast    Address Family Modifier

IP Unicast Family

Basic internet routing. Interchangeable with BGP-4.

AFI SAFI Name
1 (IPv4) 1 (Unicast) IPv4 Unicast
2 (IPv6) 1 (Unicast) IPv6 Unicast
1 (IPv4) 2 (Multicast) IPv4 Multicast
2 (IPv6) 2 (Multicast) IPv6 Multicast

Topology Example:

unicast-ipv4

Cisco Configuration Example:

1
2
3
4
5
6
7
8
r1#
router bgp 100
 neighbor 192.168.12.2 remote-as 200
 !
 address-family ipv4
  network 1.1.1.1 mask 255.255.255.255
  neighbor 192.168.12.2 activate
 exit-address-family
1
2
3
4
5
6
7
8
#r2
router bgp 200
 neighbor 192.168.12.1 remote-as 100
 !
 address-family ipv4
  network 2.2.2.2 mask 255.255.255.255
  neighbor 192.168.12.1 activate
 exit-address-family

Packet Capture:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Border Gateway Protocol - UPDATE Message
    Marker: ffffffffffffffffffffffffffffffff
    Length: 55
    Type: UPDATE Message (2)
    Withdrawn Routes Length: 0
    Total Path Attribute Length: 27
    Path attributes
        Path Attribute - ORIGIN: IGP
        Path Attribute - AS_PATH: 100
        Path Attribute - NEXT_HOP: 192.168.12.1
        Path Attribute - MULTI_EXIT_DISC: 0
    Network Layer Reachability Information (NLRI)
        1.1.1.1/32
            NLRI prefix length: 32
            NLRI prefix: 1.1.1.1

IP L3VPN Family

BGP L3VPN is used to exchange VPN (VRF) routes. Also called VPNv4 and VPNv6.

AFI SAFI Name
1 (IPv4) 128 (Labeled VPN Unicast) IPv4 L3VPN Unicast (VPNv4)
2 (IPv6) 128 (Labeled VPN Unicast) IPv4 L3VPN Unicast (VPNv6)
1 (IPv4) 129 (Labeled VPN Multicast) IPv4 L3VPN Multicast
2 (IPv6) 129 (Labeled VPN Multicast) IPv6 L3VPN Multicast

Topology Example:

unicast-vpn

Cisco Configuration Example:

1
2
3
4
5
6
7
8
9
10
11
12
#r1
router bgp 100
 neighbor 192.168.12.2 remote-as 100
 !
 address-family vpnv4
  neighbor 192.168.12.2 activate
  neighbor 192.168.12.2 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf customer
  network 11.11.11.11 mask 255.255.255.255
 exit-address-family
1
2
3
4
5
6
7
8
9
10
11
12
#r2
router bgp 100
 neighbor 192.168.12.1 remote-as 100
 !
 address-family vpnv4
  neighbor 192.168.12.1 activate
  neighbor 192.168.12.1 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf customer
  network 22.22.22.22 mask 255.255.255.255
 exit-address-family

Packet Capture:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Border Gateway Protocol - UPDATE Message
    Marker: ffffffffffffffffffffffffffffffff
    Length: 91
    Type: UPDATE Message (2)
    Withdrawn Routes Length: 0
    Total Path Attribute Length: 68
    Path attributes
        Path Attribute - MP_REACH_NLRI
            Flags: 0x80, Optional, Non-transitive, Complete
            Type Code: MP_REACH_NLRI (14)
            Length: 33
            Address family identifier (AFI): IPv4 (1)
            Subsequent address family identifier (SAFI): Labeled VPN Unicast (128)
            Next hop:  RD=0:0 IPv4=192.168.12.1
            Number of Subnetwork points of attachment (SNPA): 0
            Network Layer Reachability Information (NLRI)
                BGP Prefix
                    Prefix Length: 120
                    Label Stack: 16 (bottom)
                    Route Distinguisher: 100:1
                    MP Reach NLRI IPv4 prefix: 11.11.11.11
        Path Attribute - ORIGIN: IGP
        Path Attribute - AS_PATH: empty
        Path Attribute - MULTI_EXIT_DISC: 0
        Path Attribute - LOCAL_PREF: 100
        Path Attribute - EXTENDED_COMMUNITIES
            Flags: 0xc0, Optional, Transitive, Complete
            Type Code: EXTENDED_COMMUNITIES (16)
            Length: 8
            Carried extended communities: (1 community)
                Route Target: 100:1 [Transitive 2-Octet AS-Specific]
                    Type: Transitive 2-Octet AS-Specific (0x00)
                    Subtype (AS2): Route Target (0x02)
                    2-Octet AS: 100
                    4-Octet AN: 1

EVPN Family

MPLS-Based Ethernet VPN (BGP EVPN) can provide L2VPN services such as data-center interconnection (DCI). Designed as an alternative for VPLS.

IP tunneling such as Virtual Extensible LAN protocol (VXLAN) can provide L2 and L3 overlay networks with EVPN. (VXLAN BGP EVPN)

EVPN Virtual Private Wire Service (EVPN VPWS)

AFI SAFI Name
25 (L2VPN) 70 (EVPN) VPN EVPN BGP

Topology Example:

unicast-vpn

Cisco Configuration Example:

1
2
#r1

1
2
#r2

Packet Capture:

1
2
Border Gateway Protocol - UPDATE Message

IP Labeled Unicast Family

BGP-LU used to distribute a MPLS label mapped to a route. Not available on IOSv image. Allows for sending IP Unicast routes with MPLS tag information.

AFI SAFI Name
1 (IPv4) 4 (Labeled Unicast) IPv4 Labeled Unicast
2 (IPv6) 4 (Labeled Unicast) IPv6 Labeled Unicast

Cisco Configuration Example:

1
2
router bgp 1
  address-family ipv4 labeled-unicast

Visual Combinations

visual-mpbgp

Sources

TODO:

  • Unicast IPv4

  • Unicast IPv6

  • Multicast IPv4

  • Multicast IPv6

  • VPN IPv4

  • VPN IPv6

  • L2VPN

  • Route-target

  • VPLS

  • VPWS

  • xconnect

  • pseudowire

  • IP Unicast Family

  • IP Labeled Unicast Family

  • IP L3VPN Family

  • Link-State Family

  • Flow Specification Family

  • MCAST-VPN Family

  • EVPN Family

  • Route Target Constrain Family

  • VPLS ?

Author：Martin

Link：https://dbnservers.net/network/mp-bgp-address-families/

Publish date：December 5th 2021, 7:00:00 pm

Update date：February 8th 2023, 3:30:42 am

License：creative commons 4.0

CATALOG
  1. 1. Definitions
  2. 2. Table
    1. 2.1. Address family
    2. 2.2. Address Family Modifier
  3. 3. IP Unicast Family
  4. 4. IP L3VPN Family
  5. 5. EVPN Family
  6. 6. IP Labeled Unicast Family
  7. 7. Visual Combinations
  8. 8. Sources
  9. 9. TODO:
network cloud blog networking frontend
Total : 9
2023
2022
2021
frr bgp mpbgp aws python typescript docker github ubuntu cisco mpls ospf isis hexo iterm Python consulting react javascript