[Cisco Packet Tracer] OSPF hello messages not received

[Jeff_T1985]

Hi everyone,

As part of my CCNA study, I'm trying to build a pet LAN network which consists mainly two subnets: R1, R2 on subnet 192.168.0.0/24 and R4, R5 on subnet 192.168.1.0/24. Layer 3 switch 1 is used for interconnection between the two subnets. Everything up to this point is okay.

However, things went wrong when I tried to build OSPF adjacency: there is no hello packets exchange between L3 switch (SW1) and R1, R2. I looked up into the "debug ip ospf adj" log on both SW1, R1 and R2, it turned out that the packets sent by SW1 are not received by R1 and R2 at all (and vice versa)  even though layer 3 connection between them is up and running (ping command works).

I've already spent hours on this, tried all the possible ways that I can think of without success. Anybody out there happens to have the same problem?

Here is the topology:

This is the result of running "Show ip ospf interface" on SW1, as you can see, it has no neighbor on Vlan1 which R1 and R2 also sit on:

Loopback0 is up, line protocol is up
  Internet address is 1.1.1.1/32, Area 2
  Process ID 1, Router ID 1.1.1.1, Network Type LOOPBACK, Cost: 1
  Loopback interface is treated as a stub Host
Vlan2 is up, line protocol is up
  Internet address is 192.168.1.101/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DROTHER, Priority 1
  Designated Router (ID) 192.168.2.6, Interface address 192.168.1.6
  Backup Designated Router (ID) 192.168.1.5, Interface address 192.168.1.5
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:04
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 192.168.2.6  (Designated Router)
    Adjacent with neighbor 192.168.1.5  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
Vlan1 is up, line protocol is up
  Internet address is 192.168.0.101/24, Area 1
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 1.1.1.1, Interface address 192.168.0.101
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:05
  Index 3/3, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0
  Suppress hello for 0 neighbor(s)

This is what I got from "show run" on SW1:

router ospf 1
 log-adjacency-changes
 network 1.1.1.1 0.0.0.0 area 2
 network 192.168.1.0 0.0.0.255 area 0
 network 192.168.0.0 0.0.0.255 area 1

The result of running "Show ip ospf interface" on R1:

FastEthernet0/0 is up, line protocol is up
  Internet address is 192.168.0.2/24, Area 1
  Process ID 1, Router ID 192.168.0.2, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 192.168.0.3, Interface address 192.168.0.3
  Backup Designated Router (ID) 192.168.0.2, Interface address 192.168.0.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:09
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.3  (Designated Router)
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 1

From "show run" on R1:

router ospf 1
 log-adjacency-changes
 network 192.168.0.0 0.0.0.255 area 1
 

From "show ip ospf neighbor" on R1 (192.168.0.3 is the address of R2):

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.0.3       1   FULL/DR         00:00:33    192.168.0.3     FastEthernet0/0

[Jon Marshall]

Jeff

Can't read your attached file.

Can you post the configuration of the devices and a topology diagram as attachments as not all of use have PT and then we can have a look.

Your description is also confusing ie. you have two routers R1/R2 on one subnet which doesn't make a lot of sense unless you mean you are running HSRP between the routers for the same subnet and then using a different subnet to connect to the L3 switch.

Like I say, if you can post the configurations and also a quick diagram or PT layout we should be able to help.

Jon

[Jeff_T1985]

I just gave some more details, hope it helps.

[carlosacosta234 · Accepted solution]

Hi Jeff

Router1 and router 2 do not exchange hello packets with Switch1 and the other routers because you have OSPF authentication on Router1 and Router2, You should configure authentication on every device you want to exchange OSPF hello packets, or completly remove the authentication. Also you have to add the 192.168.2.0/24 network on Router5's Ospf process if you want the computer to communicate.

Regards.

[Jeff_T1985]

Thanks Carlos!  That's really helpful!

Just another question:  I considered authentication as the possible cause of the problem. However, running "show ip ospf" command on R1 gave the following result:

    Area 1
        Number of interfaces in this area is 1
        Area has no authentication
        SPF algorithm executed 5 times
        Area ranges are
        Number of LSA 3. Checksum Sum 0x0267df
        Number of opaque link LSA 0. Checksum Sum 0x000000
        Number of DCbitless LSA 0
        Number of indication LSA 0
        Number of DoNotAge LSA 0
        Flood list length 0

It clearly states that the area has no authentication. That's why I moved on.

Would you please explain a little on why it says no authentication when there actually is one?

[carlosacosta234]

The authentication you configured was for the interface fa0/0 on Router1.

FastEthernet0/0 is up, line protocol is up
  Internet address is 192.168.0.2/24, Area 1
  Process ID 1, Router ID 192.168.0.2, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 192.168.0.3, Interface address 192.168.0.3
  Backup Designated Router (ID) 192.168.0.2, Interface address 192.168.0.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:09
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.3  (Designated Router)
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 1

The output for "show ip ospf"  states that the area has no authentication as you said, but it's the authentication for the area 1 not the interface. you can enable area authentication in the router configuration mode with the command "area 1 authentication [message-digest]".

"area authentication

To enable authentication for an OSPF area, use the area authentication command in router configuration mode. To remove an authentication specification of an area or a specified area from the configuration, use the no form of this command.

area area-id authentication [message-digest]

no area area-id authentication [message-digest]

"

http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfospf.html