ospf nei down

[mahesh18]

hi ,

here is device logs

00318: Dec 12 06:31:55.468 EST: %MSDP-5-PEER_UPDOWN: Session to peer 10.225.205.12 going down
000319: Dec 12 06:32:07.076 EST: %MSDP-5-PEER_UPDOWN: Session to peer 10.226.203.11 going down
000320: Dec 12 06:32:07.508 EST: %OSPF-5-ADJCHG: Process 3738, Nbr 10.225.205.1 2on GigabitEthernet1/22 from FULL to DOWN, Neighbor Down: Dead timer expired
000321: Dec 12 06:32:41.876 EST: %MSDP-5-PEER_UPDOWN: Session to peer 10.225.205.12 going up
000322: Dec 12 06:32:43.656 EST: %MSDP-5-PEER_UPDOWN: Session to peer 10.226.203.11 going up
000323: Dec 12 06:33:09.612 EST: %PIM-5-NBRCHG: neighbor 10.27.12.21 DOWN on interface GigabitEthernet1/22 (vrf default) DR
000324: Dec 12 06:33:09.612 EST: %PIM-5-DRCHG: DR change from neighbor 10.27.12.21 to 10.27.12.21 on interface GigabitEthernet1/22 (vrf default)

can some tell me if ospf nei us up or down i check the int gi1/22 it is up up

GigabitEthernet1/22 is up, line protocol is up (connected)

also

sh ip ospf  int gi1/22
GigabitEthernet1/22 is up, line protocol is up (connected)
  Internet Address 10.27.12.21/30, Area 119
  Process ID 3738, Router ID 10.27.12.15, Network Type POINT_TO_POINT, Cost: 2
  Transmit Delay is 1 sec, State POINT_TO_POINT
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:02
  Supports Link-local Signaling (LLS)
  Index 10/10, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 40
  Last flood scan time is 0 msec, maximum is 12 msec
  Neighbor Count is 0, Adjacent neighbor count is 0
  Suppress hello for 0 neighbor(s)

thanks

mahesh

[Richard Burts · Accepted solution]

Mahesh

It may help to think about the extent of the layer 3 domain (what is the boundary of the layer 3 domain to which your switch is connected), the extent of the layer 2 domain (what is the boundary of the layer 2 domain to which your switch is connected) and the boundary of the layer 1 domain (what is the boundary of the layer 1 domain to which your switch is connected).

The layer 3 domain is the group of devices that are locally connected at layer 3. Since your switch and its OSPF neighbor are in the same subnet they are in the same layer 3 domain, and since you have indicated that this is functionaly a point to point connection they both function as boundary points for the layer 3 domain. The fact that you could not ping to the OSPF neighbor device is an indication that there was a problem within the layer 3 domain.

The layer 2 domain is the group of devices that are locally connected at layer 2. In early times of networking, for example 10Base2 or 10Base5, the boundary of layer 2 and of layer 3 would be the same. But as networking progressed from the use of bridges and hubs, to the use of switches they boundary of layer 2 became different from the boundary of layer 3. It is very likely that your switch has a layer 2 boundary at the provider device that gives you an Ethernet handoff to the MAN network. It is likely that there are layer 2 boundaries within the provider network, and that there is a layer 2 boundary between the provider device and the OSPF neighbor device. Given your post that the provider was doing maintenance we can assume that there was a problem within the layer 2 domain within the provider network, while your layer 2 domain of your device remained up (and without problem).

The layer 1 domain is the group of devices that are locally connected at layer 1. In you case there is almost certainly a layer 1 domain between you and the provider device that gives an Ethernet handoff. And there are other layer 1 domains between the provider devices, and another layer 1 domain between the OSPF neighbor device and its provider Ethernet handoff.

So yes we can say that layer 1 and 2 were down somewhere (within the provider network) but that layer 1 and 2 remained up at your site and at the site of the OSPF neighbor.

HTH

Rick

[mahesh18]

hi all,

Many thanks  to all of you.

Specially Richard burts  for answering my question in detail

regards

mahesh