Forward iBGP VPNv4 routes from PE to VRF of CE

[lukassgg]

Good Morning, 

We're having troubles redistributing routes learned over iBGP VPNv4 from a PE to the VRF Customer1 of a connected CE.

The PE (XR3) receives the IPv4 route 10.2.0.0/24 over iBGP VPNv4 from the RR (2011::1):

OS is Cisco IOS XR.

RP/0/RP0/CPU0:XR3#show bgp vpnv4 unicast neighbors 2011::1 routes
Fri Dec 2 08:27:45.456 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: 0x0 RD version: 0
BGP main routing table version 7321
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: 1:1 (default for vrf Customer1)
*>i10.2.0.0/24 2015::1 100 0 64700 i
Processed 1 prefixes, 1 paths

But the PE (XR3) doesn't forward this route 10.2.0.0/24 to the VRF Customer1 of the, over eBGP connected, CE (10.36.0.2):

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors 10.36.0.2 advertised-routes
Fri Dec 2 08:31:35.239 UTC
RP/0/RP0/CPU0:XR3#

We're running dualstack (IPv4, IPv6) and the PE receives the IPv6 route fd00:a::/112 from our RR.

RP/0/RP0/CPU0:XR3#show bgp vpnv6 unicast neighbors 2011::1 routes
Fri Dec 2 08:55:51.047 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: 0x0 RD version: 0
BGP main routing table version 56
BGP NSR Initial initsync version 1 (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: 1:1 (default for vrf Customer1)
*>ifd00:a::/112 2015::1 100 0 64700 i
Processed 1 prefixes, 1 paths

And also forwards this IPv6 route fd00:a::/112 to to VRF for our CE.

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv6 unicast neighbors 2001:db8:36::6 advertised-routes
Fri Dec 2 08:57:15.310 UTC
Network Next Hop From AS Path
Route Distinguisher: 1:1 (default for vrf Customer1)
fd00:a::/112 2001:db8:36::3 2011::1 65000 64700i
Processed 1 prefixes, 1 paths

So I'm assuming we're probably missing something in the BGP IPv4 unicast settings of our PE (XR3), that doesn't forward the route 10.2.0.0/24 to our VRF Customer1 of the CE. 

This is our PE (XR3) BGP configuration:

RP/0/RP0/CPU0:XR3#show run | begin bgp
Fri Dec 2 08:39:03.632 UTC
Building configuration...
router bgp 65000
bgp router-id 3.3.3.3
address-family ipv4 unicast
!
address-family vpnv4 unicast
!
address-family ipv6 unicast
!
address-family vpnv6 unicast
segment-routing srv6
locator MAIN
!
neighbor 2011::1 (This is the Route Reflector)
remote-as 65000
update-source Loopback0
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!
vrf Customer1
rd 1:1
address-family ipv4 unicast
!
address-family ipv6 unicast
segment-routing srv6
alloc mode per-ce
!
neighbor 10.36.0.2 (This is our CE IPv4)
remote-as 64800
update-source GigabitEthernet0/0/0/4
address-family ipv4 unicast
route-policy pass in
route-policy pass out
next-hop-self
!
neighbor 2001:db8:36::6 (This is our CE IPv6)
remote-as 64800
update-source GigabitEthernet0/0/0/4
address-family ipv6 unicast
route-policy pass in
route-policy pass out
next-hop-self




Thanks for any help in advance.

edit:

BGP IPv4 unicast- and BGP IPv6 unicast-peering is established between PE (XR3) and CE.

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors brief
Fri Dec 2 09:13:38.275 UTC
Neighbor Spk AS Description Up/Down NBRState
10.36.0.2 0 64800 1d18h Established


RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv6 unicast neighbors brief
Fri Dec 2 09:14:49.187 UTC
Neighbor Spk AS Description Up/Down NBRState
2001:db8:36::6 0 64800 1d18h Established

Global VRF Config on PE (XR3):

RP/0/RP0/CPU0:XR3#show run vrf
Fri Dec 2 09:21:42.584 UTC
vrf Customer1
address-family ipv4 unicast
import route-target
1:1
export route-target
1:1
address-family ipv6 unicast
import route-target
1:1
export route-target
1:1

[MHM Cisco World]

@Harold Ritter get the issue.

[Harold Ritter · Accepted solution]

Hi @lukassgg ,

You are missing a few configuration statements for VPNv4 to work properly. You have them configured for VPNv6 that is why the ipv6 routes are passed to the CE without a problem.

router bgp 65000

address-family vpnv4 unicast

segment-routing srv6

locator MAIN

!

vrf Customer1

rd 1:1

address-family ipv4 unicast

segment-routing srv6

alloc mode per-ce

!

Regards,

[lukassgg]

Hi @Harold Ritter ,

thank you very much for your response. 

I implemented your changes, but unfortunately there are still no routes being advertised from PE (XR3) to the VRF of our CE.

RP/0/RP0/CPU0:XR3#show run | begin bgp
Fri Dec 2 14:15:19.261 UTC
Building configuration...
router bgp 65000
bgp router-id 3.3.3.3
address-family ipv4 unicast
!
address-family vpnv4 unicast
segment-routing srv6
locator MAIN
!
address-family ipv6 unicast
!
address-family vpnv6 unicast
segment-routing srv6
locator MAIN
!
neighbor 2011::1
remote-as 65000
update-source Loopback0
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!
vrf Customer1
rd 1:1
address-family ipv4 unicast
segment-routing srv6
alloc mode per-ce
!
address-family ipv6 unicast
segment-routing srv6
alloc mode per-ce
!
neighbor 10.36.0.2
remote-as 64800
update-source GigabitEthernet0/0/0/4
address-family ipv4 unicast
route-policy pass in
route-policy pass out
next-hop-self
!
neighbor 2001:db8:36::6
remote-as 64800
update-source GigabitEthernet0/0/0/4
address-family ipv6 unicast
route-policy pass in
route-policy pass out
next-hop-self



RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors 10.36.0.2 advertised-routes
Fri Dec 2 14:19:12.968 UTC
RP/0/RP0/CPU0:XR3#

Looking forward to your response.

[MHM Cisco World]

does BGP have active session to this neighbor ?
I see you use g0/0/4 as update source for both address family IPv4 and IPv6 ?

[Harold Ritter]

I @MHM Cisco World ,

Here's the output that was given in the original post, showing that both IPv6 and IPv4 neighbours are up.

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors brief
Fri Dec 2 09:13:38.275 UTC
Neighbor Spk AS Description Up/Down NBRState
10.36.0.2 0 64800 1d18h Established


RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv6 unicast neighbors brief
Fri Dec 2 09:14:49.187 UTC
Neighbor Spk AS Description Up/Down NBRState
2001:db8:36::6 0 64800 1d18h Established

Regards,

[lukassgg]

If you mean the eBGP session between PE (XR3) and CE then yes. 

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors brief
Fri Dec 2 14:38:19.869 UTC
Neighbor Spk AS Description Up/Down NBRState
10.36.0.2 0 64800 2d00h Established

Yes, we use the same interface for IPv4- and IPv6-BGP peering.
We wanted both IPv4 and IPv6 peering between PE and CE.

[MHM Cisco World]

you meaning G0/0/4 is dual stacking ?

[lukassgg]

Yes.

[Harold Ritter]

Hi @lukassgg ,

Can you post the output for the following commands:

sh bgp vpnv4 unicast vrf Customer1 10.2.0.0/24

sh bgp vrf Customer1 ipv4 uni 10.2.0.0/24

show route vrf Customer1 10.2.0.0/24

Regards,

[lukassgg]

RP/0/RP0/CPU0:XR3#show bgp vpnv4 unicast vrf Customer1 10.2.0.0/24
Fri Dec 2 14:48:39.245 UTC
BGP routing table entry for 10.2.0.0/24, Route Distinguisher: 1:1
Versions:
Process bRIB/RIB SendTblVer
Speaker 387345 387345
Last Modified: Dec 2 14:48:07.458 for 00:00:31
Paths: (1 available, best #1)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
64700
2015::1 (metric 10) from 2011::1 (5.5.5.5)
Received Label 24000
Origin IGP, localpref 100, valid, internal, best, group-best, import-candidate, imported
Received Path ID 0, Local Path ID 1, version 387345
Extended community: RT:1:1
Originator: 5.5.5.5, Cluster list: 1.1.1.1
Source AFI: VPNv4 Unicast, Source VRF: Customer1, Source Route Distinguisher: 1:1

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast
Fri Dec 2 14:49:53.833 UTC
BGP VRF Customer1, state: Active
BGP Route Distinguisher: 1:1
VRF ID: 0x60000003
BGP router identifier 3.3.3.3, local AS number 65000
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000003 RD version: 387345
BGP main routing table version 387345
BGP NSR Initial initsync version 2 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
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: 1:1 (default for vrf Customer1)
r>i10.2.0.0/24 2015::1 100 0 64700 i
*> 10.6.0.1/32 10.36.0.2 0 0 64800 i
Processed 2 prefixes, 2 paths

RP/0/RP0/CPU0:XR3#show route vrf Customer1 10.2.0.0/24
Fri Dec 2 14:50:56.965 UTC
% Network not in table

[Harold Ritter]

Hi @lukassgg ,

10.2.0.0/24 has a RIB failure condition, but this route is not present in the RIB. What IOS-XR version are you running and on what platform?

Can you do a

clear bgp vpnv4 uni * soft in

and see if it clears the RIB failure condition?

Regards,

[MHM Cisco World]

r>i10.2.0.0/24 2015::1 100 0 64700 i <<--

@Harold Ritter  mention the route is rib failure, and I see Not advertised to any peer

which can cause of rib failure route.

the interesting point here the next-hop, 
we talk about IPv4 but the next-hop is IPv6.

so I think the source of this issue is from the origin of this route. 

[Harold Ritter]

Hi @lukassgg ,

Can you check the originating PE (5.5.5.5) to make sure that it is not missing the SRv6 configuration statements like XR3 did?

Regards,

[lukassgg]

Hi @Harold Ritter 

You're so right, I totally forgot about that.
I added the missing SRv6 configuration on the other PE called XR5 and it seems to work.

The PE (XR3) now advertises the network 10.2.0.0/24 to the CE1

RP/0/RP0/CPU0:XR3#show bgp vrf Customer1 ipv4 unicast neighbors 10.36.0.2 advertised-routes
Fri Dec 2 18:01:38.960 UTC
Network Next Hop From AS Path
Route Distinguisher: 1:1 (default for vrf Customer1)
10.2.0.0/24 10.36.0.1 2011::1 65000 64700i
Processed 1 prefixes, 1 paths

No RIB-failure message anymore.

And the route 10.2.0.0/24 is even visible on the CE1.

CE1#show ip route
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, m - OMP
n - NAT, Ni - NAT inside, No - NAT outside, Nd - NAT DIA
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
H - NHRP, G - NHRP registered, g - NHRP registration summary
o - ODR, P - periodic downloaded static route, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is 192.168.123.1 to network 0.0.0.0

S* 0.0.0.0/0 [254/0] via 192.168.123.1
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
B 10.2.0.0/24 [20/0] via 10.36.0.1, 00:29:07
C 10.6.0.1/32 is directly connected, Loopback0
C 10.36.0.0/30 is directly connected, GigabitEthernet2
L 10.36.0.2/32 is directly connected, GigabitEthernet2
192.168.123.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.123.0/24 is directly connected, GigabitEthernet1
L 192.168.123.173/32 is directly connected, GigabitEthernet1

Likewise the route to the network on CE1 10.6.0.1/32 is now also being advertised from the other PE (XR5) to the other CE device.

RP/0/RP0/CPU0:XR5#show bgp vrf Customer1 ipv4 unicast neighbors 10.101.10.10 advertised-routes
Fri Dec 2 18:06:00.014 UTC
Network Next Hop From AS Path
Route Distinguisher: 1:1 (default for vrf Customer1)
10.6.0.1/32 10.101.10.5 2011::1 65000 64800i
Processed 1 prefixes, 1 paths

Thank you so much