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Beginner

Nexus OSPF Clarification

Hi Guys,

 

We have a scenario where we have 2 x Nexus 3548 Switches that are peered together and are working fine.

 

Recently we had the need to start running OSPF between them and the firewalls, but i am not qutie sure if i had it setup correctly. Each Firewall is connected to 1 of the Nexus Switches.

 

Adjentcy is forming fine, but the problem is that on each OSPF instance, the nexus switches are forming adjentcy between them as well.


My question is this normal, or is there a spesific way to configure Nexus Switches for OSPF?

 

For an example:

 

 

 

N3K-SW1
interface Vlan2
  no shutdown
  ip address 10.10.2.101/24
  ip router ospf 254 area 0.0.0.254
  hsrp version 2
  hsrp 2
    preempt
    priority 120
    ip 10.10.2.1

 

router ospf 254
  router-id 10.10.2.101 

 

 OSPF Process ID 254 VRF default
 Total number of neighbors: 2
 Neighbor ID     Pri State            Up Time  Address         Interface
 10.10.2.2         1 FULL/DR          00:20:00 10.10.2.2       Vlan2
 10.10.2.102       1 FULL/BDR         00:20:04 10.10.2.102     Vlan2

 

N3K-SW2

interface Vlan2
  no shutdown
  ip address 10.10.2.102/24
  ip router ospf 254 area 0.0.0.254
  hsrp version 2
  hsrp 2
    preempt
    priority 90
    ip 10.10.2.1

 

 router ospf 254
  router-id 10.10.2.102

 

 OSPF Process ID 254 VRF default
 Total number of neighbors: 2
 Neighbor ID     Pri State            Up Time  Address         Interface
 10.10.2.2         1 FULL/DR          00:19:34 10.10.2.2       Vlan2
 10.10.2.101       1 FULL/DROTHER     00:19:31 10.10.2.101     Vlan2

 

The same scenario is happening with EIGRP if i try to set up adjaceny with a 6880X VSS;

 

N3K-SW1

 

interface Vlan999
  no shutdown
  ip address 172.16.99.31/24
  ip router eigrp 172
  hsrp version 2
  hsrp 99
    preempt
    priority 120
    ip 172.16.99.33

 

IP-EIGRP neighbors for process 172 VRF default
H   Address                 Interface       Hold  Uptime  SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
1   172.16.99.1             Vlan999         13   6w5d      6    200   0   1881
0   172.16.99.32            Vlan999         11   19w0d     1    200   0   12632339

 

N3K-SW2

interface Vlan999
  no shutdown
  ip address 172.16.99.32/24
  ip router eigrp 172
  hsrp version 2
  hsrp 99
    preempt
    priority 80
    ip 172.16.99.33

 

IP-EIGRP neighbors for process 172 VRF default
H   Address                 Interface       Hold  Uptime  SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
1   172.16.99.1             Vlan999         10   2w5d      6    200   0   1881
0   172.16.99.31            Vlan999         13   19w0d     1    200   0   12722311

 

Thank you in advance,

Niko

3 REPLIES
Rising star

Re: Nexus OSPF Clarification

What is the output of "sh ospf neigh" on the FW ?

Try using OSPF Point-to-Point network between N3k1-N3k2, FW1-N3k1, FW2-N3k2
Highlighted
VIP Advisor

Re: Nexus OSPF Clarification

Hello

Just like to add you maybe be applicable to use Point-to-multipoint non-broadcast network type depending if the layer 3 interface is a SVI



kind regards
Paul

Please don't forget to rate any posts that have been helpful.
Hall of Fame Master

Re: Nexus OSPF Clarification

Perhaps we can get some clarification from the original poster. I am not sure that there is a problem that needs to be fixed. In reading the original post it seems to me that the key question is this

My question is this normal

If I am understanding the original post correctly there are 2 switches that are connected in at least 1 vlan and operating independently. These switches are connected to 2 firewalls. And when a routing protocol is configured on the vlan/subnet connecting the switches to the firewalls then the switches become neighbors. From my perspective that is a normal behavior and not something that needs to be fixed. If there is something I am not understanding correctly then I hope that the original poster will provide clarification.

 

HTH

 

Rick

 

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