huawei arg3 router how to - troubleshooting ospf: area mismatch

HUAWEI ROUTER ARG3 - HOW TO

Troubleshooting OSPF - Lesson 1: Area mismatch

HUAWEI ARG3 ROUTER HOW TO



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



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.



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


10.1.2.0/24 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


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.



3. Check RouterA routing table

Checking RouterA routing table

<RouterA> display ip routing-table


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










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.



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.



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.



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.



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



Checking the routing table on RouterC [RouterC] disp ip routing-table


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










[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.



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huawei arg3 router how to - troubleshooting ospf: area mismatch

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