Cisco 4510 does not establish ospf in vlan interface (ospf net point-to-point)

[Erico Verissimo]

Hello,

I have a connection between two routers provided by metro ethernet. The connection is as below:

R1<------metro ethernet (ISP)-------->R2

R1 Cisco 2911 - Physical interface G0/2

R2 Cisco 4510 - Trunk vlns G2/24 and L3 on interface vlan 1322

When a set up the interfaces with "ip ospf network point-to-point" the neighbor doesn't connect but without point-to-point it goes to up "full". I need to use the point-to-point configuration because the DR election.

I really thanks any help.

Cheers.

[paul driver]

Hello

When the adjacency isnt establishing did you verify the ospf network type, for both of the L3 interfaces for any network type or mtu mismatch?

As you are aware Dr/Bdr election takes place only on Broadcast/non broadcast network types,

Can you apply a debug to see what is negating the adjacency forming - debug ip ospf adj


FYI - negating mtu mismatch - ip ospf mtu-ignore - Interface specific

res
Paul

[Erico Verissimo]

Fellows,

Thank you so much for the prompt response and I am sorry for I am late response. I am testing with ISP and the issue it is the among of broadcast that the Lan-to-Lan is sending to my end router. The ISP set up storm-control level (5%) and the ospf p2p goes full, weird is not.

Now, we are finding the source of broadcasts, but, for the moment we are using the storm-control feature.

Follow debug ip ospf adj - config ospf p2p without storm-control on ISP Link.

Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: EXCHANGE - OPTIONS/INIT do not match
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Bad seq received from 192.168.149.229
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Nbr 10.206.0.10: Prepare dbase exchange
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACE opt 0x52 flag 0x7 len 32
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACE opt 0x52 flag 0x7 len 32 mtu 1500 st ate EXSTART
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: NBR Negotiation Done. We are the SLAVE
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Nbr 10.206.0.10: Summary list built, size 1370
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACE opt 0x52 flag 0x2 len 1452
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACE opt 0x52 flag 0x7 len 32 mtu 1500 st ate EXCHANGE
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACE opt 0x52 flag 0x2 len 1452
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACE opt 0x52 flag 0x7 len 32 mtu 1500 st ate EXCHANGE
Aug 5 12:38:46.553: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACE opt 0x52 flag 0x2 len 1452
Aug 5 12:38:47.329: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACF opt 0x52 flag 0x3 len 1452 mtu 1500 state EXCHANGE
Aug 5 12:38:47.329: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACF opt 0x52 flag 0x2 len 1452
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACF opt 0x52 flag 0x3 len 1452 mtu 1500 state EXCHANGE
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACF opt 0x52 flag 0x2 len 1452
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACF opt 0x52 flag 0x3 len 1452 mtu 1500 state EXCHANGE
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACF opt 0x52 flag 0x2 len 1452
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACF opt 0x52 flag 0x3 len 1452 mtu 1500 state EXCHANGE
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFACF opt 0x52 flag 0x2 len 1452
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFACD opt 0x52 flag 0x3 len 1452 mtu 1500 state EXCHANGE
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Bad seq received from 192.168.149.229
Aug 5 12:38:47.337: OSPF-40 ADJ Gi0/2.1322: Nbr 10.206.0.10: Prepare dbase exchange
Aug 5 12:38:47.341: OSPF-40 ADJ Gi0/2.1322: Send DBD to 10.206.0.10 seq 0xFAD0 opt 0x52 flag 0x7 len 32
Aug 5 12:38:47.341: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFAD0 opt 0x52 flag 0x3 len 1452 mtu 1500 state EXSTART
Aug 5 12:38:47.341: OSPF-40 ADJ Gi0/2.1322: Unrecognized DBD for EXSTART
Aug 5 12:38:47.341: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFAD0 opt 0x52 flag 0x3 len 1452 mtu 1500 state EXSTART

-----------------------------------------------------------------------------------------------------------------

Config of my routers:

hub and spoke connection

hub router:

interface GigabitEthernet2/24

switchport trunk allowed vlan 1322
switchport autostate exclude
switchport mode trunk
load-interval 30
speed 1000
duplex full
storm-control broadcast level 5.00

interface Vlan1322
description LINK L2L TIM - 20M - REPUBLICA DO LIBANO II
bandwidth 20000
ip address 192.168.149.229 255.255.255.252
no ip redirects
no ip proxy-arp
ip ospf authentication
ip ospf authentication-key 7 135542022D2A55793E
ip ospf network point-to-point
ip ospf flood-reduction

router ospf 1
router-id 10.206.0.10

network 192.168.149.228 0.0.0.3 area 0

---------------------------------------------------------------------

campus router spoke:

interface GigabitEthernet0/2.1322
description LINK TIM - TRK - 20M
bandwidth 20000
encapsulation dot1Q 1322
ip address 192.168.149.230 255.255.255.252
no ip redirects
no ip proxy-arp
ip flow ingress
ip flow egress
ip ospf authentication
ip ospf authentication-key 7 135542022D2A55793E
ip ospf network point-to-point
ip ospf flood-reduction

router ospf 40
router-id 10.129.45.1

 network 192.168.149.228 0.0.0.3 area 0

fmd-rt-RepLibano561#sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
10.206.0.10 0 FULL/ - 00:00:34 192.168.149.229 GigabitEthernet0/2.1322

Thank you so much.

Cheers.

[paul driver · Accepted solution]

Hello

hub router:

interface Vlan1322
ip ospf mtu-ignore
exit

vlan 1322
exit

campus router spoke:

interface GigabitEthernet0/2.1322
ip ospf mtu-ignore
exit

sh ip ospf interface

 res

Paul

[Erico Verissimo]

Hello Paul,

 I put the command on the interfaces and I got the reason to this:

Aug 5 12:38:47.341: OSPF-40 ADJ Gi0/2.1322: Rcv DBD from 10.206.0.10 seq 0xFAD0 opt 0x52 flag 0x3 len 1452 mtu 1500 state EXSTART

Really thank you.

Cheers.

[ahmedshoaib]

Hi,

Can you post the configuration which you apply on both side (R1 - g0/2 & R2 - vlan 1322). It's seems that 1 of the parameters is mismatched when u configure point-to-point.

Normally a small mistake commonly done is that point-to-point configure on 1 side and 2ND side forget to configure p-t-p.

Thanks and Best regards

[Richard Burts]

I do not understand why it is important to have this neighbor relationship be point to point. The original poster says something about the DR election but I do not understand what the issue is supposed to be about DR election. It seems to me that if the neighbor relationship is established with the default network type why is that not good enough? Perhaps the original poster can clarify this?

HTH

Rick

[Joseph W. Doherty · Accepted solution]

Cannot speak for OP, but my company's standards also include setting OSPF to p2p when using a physical p2p Ethernet connection.  OSPF will establish adjacency w/o being set to p2p, in fact, often it will establish adjacency if one side is set to p2p and the other is not.

As to why we use it - in theory OSPF comes up a tiny bit faster as no need to use DR protocol on p2p link.  Also in theory, a tiny bit less overhead maintaining the adjacency.

The other advantage, OSPF shows the adjacency as p2p when the link is physically and logically p2p.

[ahmedshoaib]

Hi Joseph;

Technically you are right the OSPF adjacency will be up even 1 side as Point-to-Point and other side Broadcast (by default) due to hello and dead-interval is same. But both will not exchange the routes due to interface type are different.

Thanks & Best regards;

[Erico Verissimo]

Hello Richard,

We don't want the CPE router attended of the election between the routers on Data Center. In the DC we have routers on a multi access environment, i.e. there are election DR/BDR and our CPE are ospf p2p. Likely this scenario doesn't have any problem but if we have a CPE DR and the link among DC and CPE flapping or goes down it can occasion a routing problem.

Cheers.

[Richard Burts]

Thanks for the response. I do understand that a link going down or flapping can cause problems. I do not understand how the presence of absence of a DR makes it worse. But it is your network and your question in the forum and if you want to have the link as OSPF point to point then you certainly can do so.

HTH

Rick

[Erico Verissimo]

Hello Richard,

All of the information in this post are so important to lead to resolve problems and your post also is important for me. Thank you so much I really like this forum and I resolved a lot of problems with your help.

Best regards.

[Richard Burts]

You are welcome. I agree that these forums are excellent places to learn more about networking and to find solutions for problems that we may face.

HTH

Rick