Clarify next-hop-self in RR

[Ethan55]

I have a simple topo as below: 

R9 and R13 establish iBGP with RR. R9 is RR client of RR (10.10.10.10). R13 is a normal iBGP neighbor of RR.

I use OSPF and LDP.

R9 and R13 have VRF VPNA and exchange Lo1 as the VPNv4 route. Do Next-hop self in RR.

R13 and R9 learn the VPNv4 route of each other but can not ping each other.

R9#show ip route vrf VPN_A

Routing Table: VPN_A
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

      172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C        172.16.167.0/24 is directly connected, Loopback1
L        172.16.167.1/32 is directly connected, Loopback1
B        172.16.168.0/24 [200/0] via 10.10.10.10, 00:30:41

R13#show ip route vrf VPN_A

Routing Table: VPN_A
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

      172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
B        172.16.167.0/24 [200/0] via 10.10.10.10, 00:31:55
C        172.16.168.0/24 is directly connected, Loopback1
L        172.16.168.1/32 is directly connected, Loopback1

ICMP request out but was dropped at RR. The current configuration:

R13
vrf definition VPN_A
 rd 13.13.13.13:1
 route-target export 999:1
 route-target import 999:1
 !
 address-family ipv4
 exit-address-family
!         

interface Loopback0
 ip address 13.13.13.13 255.255.255.255
!
interface Loopback1
 vrf forwarding VPN_A
 ip address 172.16.168.1 255.255.255.0
!

router ospf 1
 network 13.13.13.13 0.0.0.0 area 0
 network 192.168.23.0 0.0.0.255 area 0
!
router bgp 7552
 bgp log-neighbor-changes
 neighbor 10.10.10.10 remote-as 7552
 neighbor 10.10.10.10 update-source Loopback0
 !
 address-family ipv4
  neighbor 10.10.10.10 activate
 exit-address-family
 !
 address-family vpnv4
  neighbor 10.10.10.10 activate
  neighbor 10.10.10.10 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf VPN_A
  redistribute connected
 exit-address-family
 

R9
vrf definition VPN_A
 rd 9.9.9.9:1
 route-target export 999:1
 route-target import 999:1
 !
 address-family ipv4
 exit-address-family
!
interface Loopback0
 ip address 9.9.9.9 255.255.255.255
!
interface Loopback1
 vrf forwarding VPN_A
 ip address 172.16.167.1 255.255.255.0
!

router ospf 1
 network 9.9.9.9 0.0.0.0 area 0
 network 192.168.29.0 0.0.0.255 area 0
!
router bgp 7552
 bgp log-neighbor-changes
 neighbor 10.10.10.10 remote-as 7552
 neighbor 10.10.10.10 update-source Loopback0
 !
 address-family ipv4
  neighbor 10.10.10.10 activate
 exit-address-family
 !
 address-family vpnv4
  neighbor 10.10.10.10 activate
  neighbor 10.10.10.10 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf VPN_A
  redistribute connected
 exit-address-family
!

RR
router bgp 7552
 bgp router-id 10.10.10.10
 address-family ipv4 unicast
 !
 address-family vpnv4 unicast
 !
 neighbor 9.9.9.9
  remote-as 7552
  update-source Loopback0
  address-family ipv4 unicast
   route-reflector-client
   next-hop-self
   soft-reconfiguration inbound always
  !
  address-family vpnv4 unicast
   route-reflector-client
   next-hop-self
   soft-reconfiguration inbound always
  !
 !
 neighbor 13.13.13.13
  remote-as 7552
  update-source Loopback0
  address-family ipv4 unicast
   next-hop-self
   soft-reconfiguration inbound always
  !
  address-family vpnv4 unicast
  next-hop-self
  soft-reconfiguration inbound always
  !
 !
! 

If I don't Next-hop self in RR, I can ping between VPNA of R13 and R9 successfully. Please help me clarify this case.

Thanks.

[Ethan55]

Hi @Harold Ritter ,

I also think it is caused by version,

Do you have any update version of IOS-XR can share with me.

Thank you.

[Harold Ritter]

Hi @Ethan55 ,

Please send me your email address in a private message and I will reach out to you with the information.

Regards,

[MHM Cisco World]

Again 

Share show ip bgp vpnv4 all 

Of RR

[Ethan55]

Thank you all guys,

I re-test with the different IOS-XR, the same configuration and finally it works well.

The version I am using and working well is:

RP/0/0/CPU0:CKV01#show version
Mon Jul 24 17:42:37.721 UTC

Cisco IOS XR Software, Version 6.0.1[Default]
Copyright (c) 2016 by Cisco Systems, Inc.

I have attached the full config in the attachment.

VPNv4 route in AGG:

RP/0/0/CPU0:CKV01#show bgp vpnv4 unicast
Mon Jul 24 17:57:31.840 UTC
BGP router identifier 10.10.10.10, local AS number 7552
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0 RD version: 0
BGP main routing table version 17
BGP NSR Initial initsync version 2 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 9.9.9.9:1
*>i172.16.167.0/24 9.9.9.9 0 100 0 ?
Route Distinguisher: 13.13.13.13:1
*>i172.16.168.0/24 13.13.13.13 0 100 0 ?

Processed 2 prefixes, 2 paths

RP/0/0/CPU0:CKV01#show bgp vpnv4 unicast advertised neighbor 9.9.9.9
Mon Jul 24 17:58:06.927 UTC
Route Distinguisher: 13.13.13.13:1
172.16.168.0/24 is advertised to 9.9.9.9
Path info:
neighbor: 13.13.13.13 neighbor router id: 13.13.13.13
valid internal best import-candidate
Received Path ID 0, Local Path ID 1, version 16
Attributes after inbound policy was applied:
next hop: 13.13.13.13
MET ORG AS LOCAL EXTCOMM
origin: incomplete metric: 0 local pref: 100
aspath:
extended community: RT:999:1
Attributes after outbound policy was applied:
next hop: 10.10.10.10
MET ORG AS LOCAL EXTCOMM
origin: incomplete metric: 0 local pref: 100
aspath:
extended community: RT:999:1
originator: 13.13.13.13 cluster list: 10.10.10.10

RP/0/0/CPU0:CKV01#show bgp vpnv4 unicast advertised neighbor 13.13.13.13
Mon Jul 24 17:58:16.386 UTC
Route Distinguisher: 9.9.9.9:1
172.16.167.0/24 is advertised to 13.13.13.13
Path info:
neighbor: 9.9.9.9 neighbor router id: 9.9.9.9
(Received from a RR-client) valid internal best import-candidate
Received Path ID 0, Local Path ID 1, version 17
Attributes after inbound policy was applied:
next hop: 9.9.9.9
MET ORG AS LOCAL EXTCOMM
origin: incomplete metric: 0 local pref: 100
aspath:
extended community: RT:999:1
Attributes after outbound policy was applied:
next hop: 10.10.10.10
MET ORG AS LOCAL EXTCOMM
origin: incomplete metric: 0 local pref: 100
aspath:
extended community: RT:999:1
originator: 9.9.9.9 cluster list: 10.10.10.10

[MHM Cisco World]

Happy news finally' 

Glad you solve issue.

Have a nice summer 

MHM

[Ethan55]

How can I show which action RR will do if it received MPLS packet from R9 (or R13), MPLS in this case have only one label (VPN label) because I use ldp implicit-null.

[MHM Cisco World]

Use mpls traceroute, check the label

Then see match label with what RR have in show mpls forwarding 

[Harold Ritter]

Hi @Ethan55 ,

"show mpls forwarding" on the RR shows you that the locally assigned VPNv4 label is swapped with the VPNv4 label received from the other PE.

Regards,