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HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
HUAWEI ARG3 ROUTER HOW TO
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
OSPF is a routing protocol with
some useful means of troubleshooting. Using the simple network scenario shown in the
picture, we will describe how it is possible to detect and solve some
common OSPF configuration error. This first lesson about OSPF troubleshooting will be focused on
“Area mismatch”. We will isolate the problem and we will correct
the configuration.
General infos and application environment
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
1. Ping RouterD from RouterC
Checking IP connectivity between RouterC
and RouterD <RouterC> ping 10.1.3.2
PING 10.1.3.2: 56 data bytes, press CTRL_C to break
Request time out
Request time out
Request time out
Request time out
Request time out
--- 10.1.3.2 ping statistics ---
5 packet(s) transmitted
0 packet(s) received
100.00% packet loss
Ping RouterD
RouterD is unreachable from RouterC, so
we have to chek RouterC routing table.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
2. Check RouterC routing table
Checking RouterC routing table
<RouterC> display ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 5 Routes : 5
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.1.0/24 Direct 0 0 D 10.1.1.2 GigabitEthernet0/0/0
10.1.1.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/0
10.1.2.0/24 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/0/0
27.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
Display the routing table
There is something
strange in the routing
table: only tne network
10.1.2.0/24 in Area 0 is
known via OSPF, there is
no information about
network 10.1.3.0/24 in
Area 2. Anayway the
OSPF neighborship with
RouterA seems to be
OK, otherwise also
network 10.1.2.0/24
would be not known to
RouterC. So we can go
on checking RouterA.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
3. Check RouterA routing table
Checking RouterA routing table
<RouterA> display ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.1.0/24 Direct 0 0 D 10.1.1.1 GigabitEthernet0/0/0
10.1.1.1/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/0
10.1.2.0/24 Direct 0 0 D 10.1.2.1 GigabitEthernet0/0/1
10.1.2.1/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
Display the routing table
There is something
strange in the routing
table: no networks are
known to RouterA via
OSPF. There is no
information about
network 10.1.3.0/24 in
Area 2. So next step will
be to check the
neighborship status of
RouterA with RouterB.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
4. Check OSPF neighborship on RouterA
Checking OSPF neighborship on RouterA
<RouterA> display ospf peer
OSPF Process 1 with Router ID 1.1.1.1
Neighbors
Area 0.0.0.1 interface 10.1.1.1(GigabitEthernet0/0/0)'s neighbors
Router ID: 3.3.3.3 Address: 10.1.1.2
State: Full Mode:Nbr is Master Priority: 1
DR: 10.1.1.2 BDR: 10.1.1.1 MTU: 0
Dead timer due in 33 sec
Retrans timer interval: 5
Neighbor is up for 00:17:58
Authentication Sequence: [ 0 ]
Display OSPF neighbors
RouteA has only one
peer OSPF that is
RouterC (Router ID:
3.3.3.3) in Area 1; there
is no information about
RouterB in Area 0. So
we have to check if
there is some
configuration error in
OSPF on RouterA.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
5. Check OSPF errors
Checking OSPF configuration errors on
RouterA (1) <RouterA> display ospf error
OSPF Process 1 with Router ID 1.1.1.1
OSPF error statistics
General packet errors:
0 : IP: received my own packet 0 : Bad packet
0 : Bad version 0 : Bad checksum
1697 : Bad area id 0 : Drop on unnumbered interface
0 : Bad virtual link 0 : Bad authentication type
0 : Bad authentication key 0 : Packet too small
0 : Packet size > ip length 0 : Transmit error
0 : Interface down 0 : Unknown neighbor
0 : Bad net segment 0 : Extern option mismatch
0 : Router id confusion
Display errors in OSPF
There are 1697 Bad
area id errors: it seems
an OSPF area
misconfiguration; so let’s
check the RouterA
configuration.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
6. Check RouterA configuration
Checking OSPF configuration errors on
RouterA (2)
<RouterA> display current-configuration
…………………………
#
ospf 1
area 0.0.0.1
network 10.1.2.0 0.0.0.255
network 10.1.1.0 0.0.0.255
#
..............................................
Display RouterA
configuration
So now we can
understand that the
problem is with network
10.1.2.0/24. This
network must be
advertised in Area 0
and not in Area 1. So
let’s correct the
configuration.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
Correcting OSPF configuration on RouterA
[RouterA] ospf
[RouterA-ospf-1] area 1
[RouterA-ospf-1-area-0.0.0.1] undo network 10.1.2.0 0.0.0.255
[RouterA-ospf-1-area-0.0.0.1] quit
[RouterA-ospf-1] area 0
[RouterA-ospf-1-area-0.0.0.0] network 10.1.2.0 0.0.0.255
[RouterA-ospf-1-area-0.0.0.0] quit
[RouterA-ospf-1] quit
7. Correct RouterA configuration
Enter OSPF process
Enter area 1 view
Exit area 1 view
Delete network 10.1.2.0/24 in the area 1
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
Checking the routing table on RouterC [RouterC] disp ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.1.0/24 Direct 0 0 D 10.1.1.2 GigabitEthernet0/0/0
10.1.1.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/0
10.1.2.0/24 OSPF 10 2 D 10.1.1.1 GigabitEthernet0/0/0
10.1.3.0/24 OSPF 10 3 D 10.1.1.1 GigabitEthernet0/0/0
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
[RouterC]
Check the routing table on RouterC to verify the OSPF routes
Now we can see that
RouterC has learned the
route to network
10.1.2.0/24 via OSPF.
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
More needs?
See hints on www.ipmax.it
Or email us your questions to [email protected]
HUAWEI ROUTER ARG3 - HOW TO
Troubleshooting OSPF - Lesson 1: Area mismatch
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