Solved: OSPF Multiarea and GRE

luisca12_ · ‎02-09-2020

Hello community,

I'm doing a troubleshooting and the following message appears in Router BR

%ADJ-5-PARENT: Midchain parent maintenance for IP midchain out of 0 65E900C0 - looped chain attempting to stack

%TUN-5-RECURDOWN: 0 temporarily disabled due to recursive routing

%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to down

01:00:11: %OSPF-5-ADJCHG: Process 110, Nbr 2.2.2.2 on Tunnel0 from FULL to DOWN, Neighbor Down: Interface down or detached

And in Router BR-2 is the following

01:00:46: %OSPF-5-ADJCHG: Process 110, Nbr 1.1.1.1 on Tunnel0 from FULL to DOWN, Neighbor Down: Dead timer expired

01:00:46: %OSPF-5-ADJCHG: Process 110, Nbr 1.1.1.1 on Tunnel0 from FULL to DOWN, Neighbor Down: Interface down or detached

I've seen other posts and they say you have to remove the default-information originate, but if you see in AREA 2, it's better not to. And in green part, and didn't even put this command.

And also, other comments say that you should remove the network 192.168.100.0/32. If I do that, the Tunnel 0 is UP, but no other networks are discovered automatically.

My question is, is there a way to let protocols complete each other routing table automatically or do I have to create static routes to get to the next hop?

NOTE: This exercise is in Packet Tracer so I cannot add priority, hello and dead intervals to the Tunnel 0 (in IPv4). But my idea was that Router BR be the DR.

Router BR

int lo 0

des Loopback Int

ip add 1.1.1.1 255.255.255.255

interface GigabitEthernet0/0/0

des FO-Link to ISP CT (186.15.236.88/30)

ip add 186.15.236.90 255.255.255.252

ip nat out

no shut

interface Tunnel 0

des Gre Tunnel to BR-2 (192.168.100.0/32)

ip add 192.168.100.1 255.255.255.252

tunnel mode gre ip

tunnel source gigabitEthernet 0/0/0

tunnel destination 186.15.236.94

router ospf 110

router-id 1.1.1.1

auto-cost reference-bandwidth 1024

network 1.1.1.1 0.0.0.0 area 0

network 172.16.10.0 0.0.63.255 area 0

network 192.168.100.0 0.0.0.3 area 0

passive-interface default

no passive-interface g0/2/0.60

no passive-interface tunnel 0

Router BR-2

int lo 0

des Loopback Int

ip add 2.2.2.2 255.255.255.255

int g0/0/0

des FO-Link to ISP (186.15.236.92/30)

ip add 186.15.236.94 255.255.255.252

ip nat out

no shut

int tunnel 0

des Gre Tunnel to BR (192.168.100.0/32)

ip add 192.168.100.2 255.255.255.252

tunnel mode gre ip

tunnel source GigabitEthernet 0/0/0

tunnel destination 186.15.236.90

router ospf 110

router-id 2.2.2.2

auto-cost reference-bandwidth 1024

passive-interface default

no passive-interface tunnel 0

no passive-interface s0/2/0

network 2.2.2.2 0.0.0.0 area 2

network 172.17.10.0 0.0.0.255 area 2

network 172.17.15.0 0.0.0.255 area 2

network 172.17.20.0 0.0.0.255 area 2

network 172.17.30.0 0.0.0.3 area 2

network 192.168.100.0 0.0.0.3 area 0

area 2 range 172.17.0.0 255.255.224.0

default-information originate

paul driver · ‎02-09-2020

Hello

@luisca12_ wrote:

My question is, is there a way to let protocols complete each other routing table automatically or do I have to create static routes to get to the next hop?

NOTE: This exercise is in Packet Tracer so I cannot add priority, hello and dead intervals to the Tunnel 0 (in IPv4). But my idea was that Router BR be the DR.

First of all the recursion is happening because of that advertised default-originate is installing a default route into both areas as such the tunnel destinations are being learned through the tunnel itself, so that default needs to be removed from being learned over the tunnel and ospf area 0 and this can be accomplished by appending a more specific default route just for area 2 rtrs so those rtrs in that area have a egress point for external routes and area2 networks will be advertised into area 0

rtr-BR2 <- ABR of area 2
router ospf 110
no default-information originate
area 2 stub no-summary

rtr ( area 2 rtrs)
router ospf 110
area 2 stub

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

View solution in original post

paul driver · ‎02-09-2020

Hello

@luisca12_ wrote:

My question is, is there a way to let protocols complete each other routing table automatically or do I have to create static routes to get to the next hop?

NOTE: This exercise is in Packet Tracer so I cannot add priority, hello and dead intervals to the Tunnel 0 (in IPv4). But my idea was that Router BR be the DR.

First of all the recursion is happening because of that advertised default-originate is installing a default route into both areas as such the tunnel destinations are being learned through the tunnel itself, so that default needs to be removed from being learned over the tunnel and ospf area 0 and this can be accomplished by appending a more specific default route just for area 2 rtrs so those rtrs in that area have a egress point for external routes and area2 networks will be advertised into area 0

rtr-BR2 <- ABR of area 2
router ospf 110
no default-information originate
area 2 stub no-summary

rtr ( area 2 rtrs)
router ospf 110
area 2 stub

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

luisca12_ · ‎02-12-2020

Dear Paul,

Thank you so much for your advice. I already test it and it worked successfully!! Now I'll do a research about the are 2 stub command.

Have a nice day.

Best regards,
Luis Solera A.

luisca12_ · ‎02-12-2020

Dear Paul,

One more question, in my topology I'm redistributing EIGRP into OSPF and vice versa. And I searched more about this Stub area and also found NSSA, so in this case area 2 stills a Stub area or a NSSA?

The roles of each router right now are:

BR-2: ASBR - Area 2 - Totally Stub Area

R-1: IR - Area 2 - Stub Area

R-2: IR - Area 2 - Stub Area

Best Regard,

Luis Solera A.