unable to get pings across a network using ospf

Associate
Joined
1 Feb 2009
Posts
2,124
So here is a diagram of my network



I am unable to get PC1 to ping 192.168.100.1. it can ping the same PC's in its same vlan, which is what is required
The router NCL can ping PC1.
Both routers can ping each other
LON can ping 192.168.100.1
Im completly stumped and ive been stck now for 2 days, so im asking for help here,

NCL sh run as follows:

NCL#sh run
Building configuration...

Current configuration : 1170 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname NCL
!

enable secret 5 $1$mERr$hx5rVt7rPNoS4wqbXKX7m0
enable password class
!

no ip domain-lookup
ip name-server 0.0.0.0
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.1
encapsulation dot1Q 1 native
ip address 170.10.1.0 255.255.252.0
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 170.10.10.0 255.255.248.0
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 170.10.20.0 255.255.240.0
!
interface FastEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface Serial0/0
ip address 170.10.100.1 255.255.255.252
ip ospf cost 1563
!
interface Serial0/1
no ip address
shutdown
!
router ospf 1
router-id 10.10.10.2
log-adjacency-changes
network 170.10.100.0 0.0.0.3 area 0
network 170.10.1.0 0.0.0.255 area 0
network 170.10.10.0 0.0.0.255 area 0
network 170.10.20.0 0.0.0.255 area 0
!
ip classless
!
line con 0
password cisco
login
line vty 0 4
password cisco
login
!
end

so is anyone able help me here figure this out? i can provide extra info if needed on the Sw's config
 
has the neighbour relationship formed ?? theres a mismatched subnet on the point-to-point serial link, that would be my first stop. you've used a /30 on one side and a /24 on the other (according to the diagram)

run

show ip ospf neighbors (and if there aren't any neighbours listed)

run

debug ip ospf adj (to watch the debug messages whilst the relationship is being formed)

and post the output :)
 
Last edited:
ah sorry, the subnet is the same on the config
interface Serial0/0
ip address 170.10.100.1 255.255.255.252
ip ospf cost 1563

edit: relationship is formed as a sh ip route confirms this:

NCL#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is not set

170.10.0.0/16 is variably subnetted, 4 subnets, 4 masks
C 170.10.0.0/22 is directly connected, FastEthernet0/0.1
C 170.10.8.0/21 is directly connected, FastEthernet0/0.10
C 170.10.16.0/20 is directly connected, FastEthernet0/0.20
C 170.10.100.0/30 is directly connected, Serial0/0
O 192.168.100.0/24 [110/1564] via 170.10.100.2, 00:04:44, Serial0/0

to get an update i had to unplug fa0/0 on NCL and plug it back in a few seconds later

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.1, changed state to down
01:28:36: OSPF: DR/BDR election on FastEthernet0/0.1
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: DR: none BDR: none
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x80000007
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x80000008
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.10, changed state to down
01:28:36: OSPF: DR/BDR election on FastEthernet0/0.10
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: DR: none BDR: none
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x80000008
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x80000009
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.20, changed state to down
01:28:36: OSPF: DR/BDR election on FastEthernet0/0.20
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: OSPF: Elect BDR 0.0.0.0
01:28:36: OSPF: Elect DR 0.0.0.0
01:28:36: DR: none BDR: none
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x80000009
01:28:36: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x8000000a
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.1, changed state to up
01:28:49: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x8000000a
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.10, changed state to up
01:28:49: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x8000000b
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.20, changed state to up
01:28:49: OSPF: Build router LSA for area 0, router ID 10.10.10.2, seq 0x8000000c
 
Last edited:
can the NCL router ping 192.168.100.1 interface on the LON router across the p2p link? if so i'd work backwards from there...

have you set the correct default-gateway on the PC1 (i assume it should be, 170.10.1.0) can you ping the default gateway?

does the LON have a valid route back to the pc's on the vlan1 subnet?
 
p2p pings correctly :)

and sucess, the default gateway on the Pc's wasnt entered, i guess it was becuase i thought that as the switches would just do this for me in the inter vlan routing

cheers for the help
 
It looks like you are using packet tracer, if that is true then although you have fixed your current issue, one good idea to use in the future is to set it to simulation mode and then do the ping. Follow the process step by step and you can follow the ping and at what point the error is.

Not as usefull in a real world environment unless you can monitor traffic at all points, but in packet tracer the simulation mode is a great diagnostic and learning tool.
 
in PT the packet used to just hang at the PC in sim mode, but yeah, PT is awsome

assumming that you actully went to the next step of the simulation, or set it to auto (because when you first start simulation mode, it pauses time) then if the packet doesn't move past the PC that would indicate an error with the PC.
 
I've used GNS3 for Rtr labs in the past - you will need some images for the Rtr's and a powerfull-ish machine to run it but its much better then Packet Tracer. I found Packet Tracer can often miss some IOS commands that can come in handy.
 
I've used GNS3 for Rtr labs in the past - you will need some images for the Rtr's and a powerfull-ish machine to run it but its much better then Packet Tracer. I found Packet Tracer can often miss some IOS commands that can come in handy.

Something that uses the actual OS that real routers uses will always be better, but even GNS3 has its limitations. If I remember right there is no switches for it (or it could just be layer 3 switches that don't work, I cant remember), getting the router IOS is not always possible for people with no access to real cisco equipment, and as you mentioned requires a powerfull machine if you want to have lots of stuff running.

Personaly I used packet tracer during my course because it did everything I needed it to for CCNA level work, and you can easily connect multiple packet tracer networks together, even over the internet.
 
Back
Top Bottom