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IOS-XR Lab 8: iBGP with Three Routers part 4 - using loopback peering

Loopback interfaces are simply logical interfaces that never go down unless they are admin shut or the hardware has a fault. For this reason, loopbacks are the primary choice to peer neighbors with.
In this lab, we will continue to use the three routers and covert peering with the IP address on the physical interface to peering with the IP address on the loopback interface.

Delete all BGP neighbor statements from all routers, commit optional till the end.

Add OPSF configuration to R1:

Use OSPF process 1.

RP/0/RP0/CPU0:R1#conf t
Tue Feb 11 14:22:04.653 UTC
RP/0/RP0/CPU0:R1(config)#router ospf 1

Add Router ID: 1.1.1.1, which is the Loopback 0 IP address.
1. Answer
```
RP/0/RP0/CPU0:R1(config-ospf)#router-id 1.1.1.1
```

Add all IP addresses/interfaces that are configured on the local router to OSPF area 0.

Answer

Shown are three different options for the same configuration:
RP/0/RP0/CPU0:R1(config-ospf)#area 0
RP/0/RP0/CPU0:R1(config-ospf-ar)#interface loopback 0
RP/0/RP0/CPU0:R1(config-ospf-ar-if)#exit
RP/0/RP0/CPU0:R1(config-ospf-ar)#exit
RP/0/RP0/CPU0:R1(config-ospf)#area 0 interface gigabitEthernet 0/0/0/0
RP/0/RP0/CPU0:R1(config-ospf-ar-if)#exit  
RP/0/RP0/CPU0:R1(config-ospf-ar)#exit
RP/0/RP0/CPU0:R1(config-ospf-ar)#exit
RP/0/RP0/CPU0:R1(config-ospf)#exit
RP/0/RP0/CPU0:R1(config)#router ospf 1 area 0 interface gigabitEthernet 0/0/0/1

Configure BGP to form a neighborship with the Loopback interfaces of the other two routers.
1. Add neighbor statement for neighbor router's loopback interface IP address.
  1. Answer
    RP/0/RP0/CPU0:R1(config)#router bgp 65000 RP/0/RP0/CPU0:R1(config-bgp)#neighbor 2.2.2.2
2. Add neighbor to same BGP ASN:
  1. Answer
    RP/0/RP0/CPU0:R1(config-bgp-nbr)#remote-as 65000
3. Configure neighbor to use Loopback 0 as the update source:
  1. Answer
    RP/0/RP0/CPU0:R1(config-bgp-nbr)#update-source loopback 0
4. Don't forget to add the neighbor to the ipv4 unicast address-family:
  1. Answer
    RP/0/RP0/CPU0:R1(config-bgp-nbr)#address-family ipv4 unicast
Repeat for each neighbor till all three routers form an iBGP relationship using OSPF.

Verify:

RP/0/RP0/CPU0:R1#show ospf database
Tue Feb 11 14:48:26.490 UTC


            OSPF Router with ID (1.1.1.1) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         992         0x80000006 0x0055a2 2
2.2.2.2         2.2.2.2         861         0x80000007 0x006955 3
3.3.3.3         3.3.3.3         44          0x80000005 0x00823e 3

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.0.0.3        2.2.2.2         1106        0x80000002 0x0047d0
10.0.1.3        3.3.3.3         808         0x80000003 0x007099
RP/0/RP0/CPU0:R1#show bgp summ
Tue Feb 11 14:48:42.660 UTC
BGP router identifier 1.1.1.1, local AS number 65000
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 12
BGP main routing table version 12
BGP NSR Initial initsync version 7 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker              12         12         12         12          12           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
2.2.2.2           0 65000      57      56       12    0    0 00:33:39          3
3.3.3.3           0 65000      35      35       12    0    0 00:31:44          3

RP/0/RP0/CPU0:R2#show ospf database
Tue Feb 11 14:49:34.669 UTC


            OSPF Router with ID (2.2.2.2) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1060        0x80000006 0x0055a2 2
2.2.2.2         2.2.2.2         927         0x80000007 0x006955 3
3.3.3.3         3.3.3.3         110         0x80000005 0x00823e 3

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.0.0.3        2.2.2.2         1172        0x80000002 0x0047d0
10.0.1.3        3.3.3.3         874         0x80000003 0x007099
RP/0/RP0/CPU0:R2#show bgp summ
Tue Feb 11 14:49:37.776 UTC
BGP router identifier 2.2.2.2, local AS number 65000
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 34
BGP main routing table version 34
BGP NSR Initial initsync version 8 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker              34         34         34         34          34           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
1.1.1.1           0 65000      71      77       34    0    0 00:34:33          3
3.3.3.3           0 65000      36      36       34    0    0 00:32:48          3

RP/0/RP0/CPU0:R3#show ospf database
Tue Feb 11 14:50:30.060 UTC


            OSPF Router with ID (3.3.3.3) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1118        0x80000006 0x0055a2 2
2.2.2.2         2.2.2.2         985         0x80000007 0x006955 3
3.3.3.3         3.3.3.3         166         0x80000005 0x00823e 3

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.0.0.3        2.2.2.2         1229        0x80000002 0x0047d0
10.0.1.3        3.3.3.3         930         0x80000003 0x007099
RP/0/RP0/CPU0:R3#show bgp summ
Tue Feb 11 14:50:34.906 UTC
BGP router identifier 3.3.3.3, local AS number 65000
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 44
BGP main routing table version 44
BGP NSR Initial initsync version 8 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker              44         44         44         44          44           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
1.1.1.1           0 65000      37      37       44    0    0 00:33:37          3
2.2.2.2           0 65000      37      37       44    0    0 00:33:46          3

Router1's ending configuration: Answer

hostname R1
!
interface Loopback0
 ipv4 address 1.1.1.1 255.255.255.255
!
interface GigabitEthernet0/0/0/0
 description R2; g 0/0/0/0; 10.0.0.3/24
 ipv4 address 10.0.0.2 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.0.2.2 255.255.255.0
!
router ospf 1
 router-id 1.1.1.1
 area 0
  interface Loopback0
  !
  interface GigabitEthernet0/0/0/0
  !
  interface GigabitEthernet0/0/0/1
  !
 !
!         
router bgp 65000
 bgp router-id 1.1.1.1
 address-family ipv4 unicast
  network 1.1.1.1/32
  network 10.0.0.0/24
  network 10.0.2.0/24
 !
 neighbor 2.2.2.2
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
 neighbor 3.3.3.3
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
!
router hsrp
 interface GigabitEthernet0/0/0/0
  address-family ipv4
   hsrp 1
    address 10.0.0.1
   !
  !
 !
!
end

Router2's ending configuration: Answer

hostname R2
!
interface Loopback0
 description Loopback0 for BGP
 ipv4 address 2.2.2.2 255.255.255.255
!  
interface GigabitEthernet0/0/0/0
 description R2; g 0/0/0/0; 10.0.0.2/24
 ipv4 address 10.0.0.3 255.255.255.0
!
interface GigabitEthernet0/0/0/1
 description R3; g 0/0/0/1; 10.0.1.3/24
 ipv4 address 10.0.1.2 255.255.255.0
!
router ospf 1
 router-id 2.2.2.2
 area 0
  interface Loopback0
  !
  interface GigabitEthernet0/0/0/0
  !
  interface GigabitEthernet0/0/0/1
  !       
 !
!
router bgp 65000
 bgp router-id 2.2.2.2
 address-family ipv4 unicast
  network 2.2.2.2/32
  network 10.0.0.0/24
  network 10.0.1.0/24
 !
 neighbor 1.1.1.1
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
 neighbor 3.3.3.3
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
!
router hsrp
 interface GigabitEthernet0/0/0/0
  address-family ipv4
   hsrp 1
    priority 50
    address 10.0.0.1
   !
  !
 !
!
end

Router3's ending configuration: Answer

hostname R3
!
interface Loopback0
 description Loopback0 for BGP
 ipv4 address 3.3.3.3 255.255.255.255
!
interface GigabitEthernet0/0/0/1
 description R2; G 0/0/0/1; 10.0.0.1.2/24
 ipv4 address 10.0.1.3 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.0.2.3 255.255.255.0
!
router ospf 1
 router-id 3.3.3.3
 area 0
  interface Loopback0
  !
  interface GigabitEthernet0/0/0/1
  !
  interface GigabitEthernet0/0/0/2
  !
 !        
!
router bgp 65000
 bgp router-id 3.3.3.3
 address-family ipv4 unicast
  network 3.3.3.3/32
  network 10.0.1.0/24
  network 10.0.2.0/24
 !
 neighbor 1.1.1.1
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
 neighbor 2.2.2.2
  remote-as 65000
  update-source Loopback0
  address-family ipv4 unicast
  !
 !
!
end

IOS-XR Lab 9: iBGP with Three Routers part 5
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IOS-XR Lab 8: iBGP with Three Routers part 4 - using loopback peering

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