Re: OSPF_SL0 from FULL to DOWN, Neighbor Down: Interface down

Hey there,

I think the issue here is that you are messing with vpn tag for external
ospf routes by setting a tag in the redistribute.
because vpn tags are different each PE learns a route to PE's loopback via
backdoor and makes the BGP learned route RIB.
Try to remove the tags so each PE uses the BGP route instead of OSPF route
to reach the sham link end point. I will fix your flapping issue.

R5

interface Loopback200
 ip vrf forwarding VPN_A
 ip address 1.1.1.1 255.255.255.255

router ospf 10 vrf VPN_A
 log-adjacency-changes
 redistribute bgp 100 subnets
 network 155.1.58.5 0.0.0.0 area 1
 area 1 sham-link 1.1.1.1 2.2.2.2 cost 1

R6

interface Loopback200
 ip vrf forwarding VPN_A
 ip address 2.2.2.2 255.255.255.255

router ospf 10 vrf VPN_A
 log-adjacency-changes
 summary-address 172.16.0.0 255.255.0.0
 redistribute bgp 100 subnets
 network 155.1.67.6 0.0.0.0 area 1
area 1 sham-link 2.2.2.2 1.1.1.1 cost 1

On 1 July 2011 12:32, Abdullah Al-Malki <a.almalki1402_at_gmail.com> wrote:

> I think you do not need the "redistribute connected under bgp IP address
> family of vrf A"
>
> On Fri, Jul 1, 2011 at 6:28 PM, Marko Milivojevic <markom_at_ipexpert.com
> >wrote:
>
> > 2a. Make sure newly created Loopbacks are reachable through MPLS
> > backbone and not through OSPF.
> >
> > --
> > Marko Milivojevic - CCIE #18427
> > Senior Technical Instructor - IPexpert
> >
> > FREE CCIE training: http://bit.ly/vLecture
> >
> > Mailto: markom_at_ipexpert.com
> > Telephone: +1.810.326.1444
> > Web: http://www.ipexpert.com/
> >
> > On Fri, Jul 1, 2011 at 04:53, Bilal Hansrod <bilal.hansrod_at_gmail.com>
> > wrote:
> > > Hi All,
> > >
> > > I am labbing up a sham-link to prefer MPLS path over backdoor OSPF
> route.
> > > The lab set-up is simple as below:
> > >
> > > R5 -> R4 (RR) -> R6
> > >
> > > I am creating a sham-link from R5 to R6, so I followed the below steps:
> > >
> > > 1. Create loopback 200 on both routers and assign to vrf
> > >
> > > B B R5
> > >
> > > B B interface Loopback200
> > > B B ip vrf forwarding VPN_A
> > > B B ip address 1.1.1.1 255.255.255.255
> > >
> > > B B R6
> > >
> > > B B interface Loopback200
> > > B B ip vrf forwarding VPN_A
> > > B B ip address 2.2.2.2 255.255.255.255
> > >
> > >
> > > 2. Advertise /32 loopback other than OSPF, so advertised via BGP
> > >
> > > B B R5
> > >
> > > B B router bgp 100
> > > B B address-family ipv4 vrf VPN_A
> > > B B network 1.1.1.1 mask 255.255.255.255
> > >
> > >
> > > B B R6
> > >
> > > B B router bgp 100
> > > B B address-family ipv4 vrf VPN_A
> > > B B network 2.2.2.2 mask 255.255.255.255
> > >
> > >
> > > 3. create sham-link
> > >
> > > B B R5
> > >
> > > B B router ospf 10 vrf VPN_A
> > > B B area 1 sham-link 1.1.1.1 2.2.2.2 cost 1
> > >
> > > B B R6
> > >
> > > B B router ospf 10 vrf VPN_A
> > > B B area 1 sham-link 2.2.2.2 1.1.1.1 cost 1
> > >
> > >
> > > Once I enabled sham-link command, the link starts to flaps. The OSPF_SL
> > > interface comes up and than within seconds it shows Interface down or
> > > detached. Please see full configuration as below with error messages
> > >
> > >
> > >
> > > R5
> > >
> > > interface Loopback200
> > > B ip vrf forwarding VPN_A
> > > B ip address 1.1.1.1 255.255.255.255
> > >
> > > router ospf 10 vrf VPN_A
> > > B log-adjacency-changes
> > > B redistribute bgp 100 subnets tag 667
> > > B network 155.1.58.5 0.0.0.0 area 1
> > > B area 1 sham-link 1.1.1.1 2.2.2.2 cost 1
> > >
> > > router ospf 1
> > > B log-adjacency-changes
> > > B network 0.0.0.0 255.255.255.255 area 0
> > >
> > >
> > > router bgp 100
> > > B no bgp default ipv4-unicast
> > > B bgp log-neighbor-changes
> > > B neighbor 150.1.4.4 remote-as 100
> > > B neighbor 150.1.4.4 update-source Loopback0
> > > B !
> > > B address-family vpnv4
> > > B neighbor 150.1.4.4 activate
> > > B neighbor 150.1.4.4 send-community extended
> > > B exit-address-family
> > >
> > > B address-family ipv4 vrf VPN_A
> > > B redistribute connected
> > > B redistribute static
> > > B redistribute ospf 10 vrf VPN_A
> > > B no synchronization
> > > B network 1.1.1.1 mask 255.255.255.255
> > > B exit-address-family
> > >
> > >
> > > R6
> > >
> > > interface Loopback200
> > > B ip vrf forwarding VPN_A
> > > B ip address 2.2.2.2 255.255.255.255
> > >
> > > router ospf 10 vrf VPN_A
> > > B log-adjacency-changes
> > > B summary-address 172.16.0.0 255.255.0.0
> > > B redistribute bgp 100 subnets tag 666
> > > B network 155.1.67.6 0.0.0.0 area 1
> > > area 1 sham-link 2.2.2.2 1.1.1.1 cost 1
> > >
> > > router ospf 1
> > > B log-adjacency-changes
> > > B network 0.0.0.0 255.255.255.255 area 0
> > >
> > > router bgp 100
> > > B no bgp default ipv4-unicast
> > > B bgp log-neighbor-changes
> > > B neighbor 150.1.4.4 remote-as 100
> > > B neighbor 150.1.4.4 update-source Loopback0
> > > B !
> > > B address-family vpnv4
> > > B neighbor 150.1.4.4 activate
> > > B neighbor 150.1.4.4 send-community extended
> > > B exit-address-family
> > >
> > >
> > > B address-family ipv4 vrf VPN_A
> > > B redistribute connected
> > > B redistribute static
> > > B redistribute ospf 10 vrf VPN_A
> > > B no synchronization
> > > B network 2.2.2.2 mask 255.255.255.255
> > > B exit-address-family
> > >
> > > Mar B 1 00:56:20.951: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from LOADING to FULL, Loading Done
> > > *Mar B 1 00:56:22.103: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from FULL to DOWN, Neighbor Down: Interface down or detached
> > > *Mar B 1 00:56:40.835: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from LOADING to FULL, Loading Done
> > > *Mar B 1 00:56:42.099: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from FULL to DOWN, Neighbor Down: Interface down or detached
> > > *Mar B 1 00:57:01.427: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from LOADING to FULL, Loading Done
> > > *Mar B 1 00:57:02.103: %OSPF-5-ADJCHG: Process 10, Nbr 172.16.5.5 on
> > OSPF_SL0
> > > from FULL to DOWN, Neighbor Down: Interface down or detached
> > >
> > >
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-- 
*Alberto*
Blogs and organic groups at http://www.ccie.net