1
As shown in Figure 1, Router A belongs to AS 100; Router B, Router C, and Router D belong to AS 200. BGP Auto FRR needs to be configure so that the route from Router A to Router D can have backup forwarding information.

Figure 1 Networking diagram of configuring BGP Auto FRR


Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure EBGP connections between Router A and Router B and between Router A and Router C. Configure IBGP connections between Router D and Router B, and between Router D and Router C.
  2. Configure routing policies on Router B and Router C to change the MED values of routes to Router D to facilitate route selection.
  3. Configure BGP Auto FRR on Router A.

Data Preparation

To complete the configuration, you need the following data:

  • Router IDs and AS numbers of Router A, Router B, Router C, and Router D
  • Names of routing policies and MED values of routes on Router B and Router C

Procedure

  1. Configure IP addresses for interfaces. The configuration details are not mentioned here.
  2. Configure EBGP connections between Router A and Router B, and between Router A and Router C. Configure IBGP connections between Router B and Router D, and between Router C and Router D. # Configure EBGP connections on Router A. 
    <RouterA> system-view

    [RouterA] bgp 100

    [RouterA-bgp] router-id 1.1.1.1

    [RouterA-bgp] peer 10.1.1.2 as-number 200

    [RouterA-bgp] peer 10.2.1.2 as-number 200
    NOTE:

    The configurations of Router B and Router C are the same as that of Router A, and the detailed configurations are not mentioned here.

    # Configure IBGP connections on Router D.

    <RouterD> system-view

    [RouterD] bgp 200

    [RouterD-bgp] router-id 4.4.4.4

    [RouterD-bgp] peer 10.3.1.1 as-number 200

    [RouterD-bgp] peer 10.4.1.1 as-number 200
    NOTE:

    The configurations on Router B and Router C are similar, and the detailed configurations are not mentioned here.
  3. Configuring routing policies on Router B and Router C so that the MED values of routes to Router D are different # Configure a routing policy on Router B. 
    <RouterB> system-view

    [RouterB] route-policy rtb permit node 10

    [RouterB-route-policy] apply cost 80

    [RouterB-route-policy] quit

    [RouterB] bgp 200

    [RouterB-bgp] ipv4-family unicast

    [RouterB-bgp-af-ipv4] peer 10.1.1.1 route-policy rtb export

    # Configure a routing policy on Router C.

    <RouterC> system-view

    [RouterC] route-policy rtc permit node 10

    [RouterC-route-policy] apply cost 120

    [RouterC-route-policy] quit

    [RouterC] bgp 200

    [RouterC-bgp] ipv4-family unicast

    [RouterC-bgp-af-ipv4] peer 10.2.1.1 route-policy rtc export

    # Advertise a route to 4.4.4.4/32 on Router D.

    [RouterD] bgp 200

    [RouterD-bgp] ipv4-family unicast

    [RouterD-bgp] network 4.4.4.4 32

    # Run the display ip routing-table verbose command on Router A to check detailed information about the learned route to 4.4.4.4/32.

    <RouterA> display ip routing-table 4.4.4.4 32 verbose
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1

Destination: 4.4.4.4/32
     Protocol: BGP             Process ID: 0
   Preference: 255                   Cost: 80
      NextHop: 10.1.1.2         Neighbour: 10.1.1.2
        State: Active Adv             Age: 00h00m12s
          Tag: 0                 Priority: low
        Label: NULL               QoSInfo: 0x0
   IndirectID: 0x4
 RelayNextHop: 0.0.0.0          Interface: Pos1/0/0
     TunnelID: 0x0                  Flags:  D

    Because the MED value of the route learnt from Router B is smaller, on Router A, the route to 4.4.4.4/32 selects the path RouterA→RouterB→RouterD. Because FRR is not configured, no backup information is available.

  4. Enabling BGP Auto FRR on Router A, and checking the routing information # Enable BGP Auto FRR on Router A. 
    <RouterA> system-view

    [RouterA] bgp 100

    [RouterA-bgp] ipv4-family unicast

    [RouterA-bgp-af-ipv4] auto-frr

    # After the configuration, run the display ip routing-table verbose command on Router A to check the routing information.

    <RouterA> display ip routing-table 4.4.4.4 32 verbose
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1

Destination: 4.4.4.4/32
     Protocol: BGP             Process ID: 0
   Preference: 255                   Cost: 80
      NextHop: 10.1.1.2         Neighbour: 10.1.1.2
        State: Active Adv             Age: 00h52m45s
          Tag: 0                 Priority: low
        Label: NULL               QoSInfo: 0x0
   IndirectID: 0x4
 RelayNextHop: 0.0.0.0          Interface: Pos1/0/0
     TunnelID: 0x0                  Flags:  D
    BkNextHop: 10.2.1.2       BkInterface: Pos2/0/0
      BkLabel: NULL           SecTunnelID: 0x0
 BkPETunnelID: 0x0        BkPESecTunnelID: 0x0
 BkIndirectID: 0x2

    The preceding information shows that Router A has a backup next hop and a backup outbound interface to 4.4.4.4/32.

Configuration Files

  • Configuration file of Router A 
    #
 sysname RouterA
#
interface Pos1/0/0
 ip address 10.1.1.1 255.255.255.0
#
interface Pos2/0/0
  ip address 10.2.1.1 255.255.255.0
#
bgp 100
 router-id 1.1.1.1
 peer 10.1.1.2 as-number 200
 peer 10.2.1.2 as-number 200
#
 ipv4-family unicast
    auto-frr
#
return
  • Configuration file of Router B 
    #
 sysname RouterB
#
interface Pos1/0/0
 ip address 10.1.1.2 255.255.255.0
#
interface Pos2/0/0
  ip address 10.3.1.1 255.255.255.0
#
bgp 200
 router-id 2.2.2.2
 peer 10.1.1.1 as-number 100
 peer 10.3.1.2 as-number 200
#
 ipv4-family unicast 
    peer 10.1.1.1 route-policy rtb export
#
route-policy rtb permit node 10
 apply cost 80
#
return
  • Configuration file of Router C 
    #
 sysname RouterC
#
interface Pos1/0/0
 ip address 10.2.1.2 255.255.255.0
#
interface Pos2/0/0
 ip address 10.4.1.1 255.255.255.0
#
bgp 200
 router-id 3.3.3.3
 peer 10.2.1.1 as-number 100
 peer 10.4.1.2 as-number 200
 #
 ipv4-family unicast
    peer 10.2.1.1 route-policy rtc export
#
route-policy rtc permit node 10
 apply cost 120
#
return
  • Configuration file of Router D 
    #
 sysname RouterD
#
interface Pos1/0/0
 ip address 10.3.1.2 255.255.255.0
#
interface Pos2/0/0
  ip address 10.4.1.2 255.255.255.0
#
interface LoopBack1
 ip address 4.4.4.4 255.255.255.255
#
bgp 200
 router-id 4.4.4.4
 peer 10.3.1.1 as-number 200
 peer 10.4.1.1 as-number 200
 #
 ipv4-family unicast
  network 4.4.4.4 255.255.255.255
#
return


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1 Comment

  1. Nagaraj

    Any one can tell how much effort this feature may take to implement.

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