Multi Area OSPF

[Bunny12375]

I have build the topology for this and for some reason the router ospf1on the left leg is not doing anythingI just need help on the left leg here is what I've done so far

Build the following network. (multi area OSPF, VLANs)

5 Routers with serial ports (router 0 connects to R1 and R2.  R1 connects to R3.  R2 connects to R4)

1 switch connects to R4 and 1 switch connects to R3. 

2 Switches (switch is attached to last router in the network)

1 end device attached to each switch

Subnet the addresses for the device requirement

Configure all routers with Loopback0 and router-ID

Configure sub interfaces on router connected to switches. 

Routers at the top of the network are Area 0

Network Leg A:  Area 1

  192.168.100.0/24; network host requirement is 100 devices

  VLAN 100

Network Leg B: Area 2

172.16.20.0/22; network host requirement is 50 devices

VLAN 200

Configure mulit area OSPF and ping successfully from Leg A to Leg B.

[Giuseppe Larosa]

Hello @Bunny12375,

an OSPF multiarea design requires that:

area 0 or 0.0.0.0 to be in the center of the network

all other areas need to be connected to area 0 via an ABR Area Border Router : a device that has an active link in area 0 and at least one link in the other area.

Check using

show ip ospf neighbors

show ip ospf database

what can be your issue.

Likely you have an ABR node with no link to area 0 . If this happens even if the device has links in two different areas it will not act as an ABR.

Or you have an area with no direct connection to area 0.

Hope to help

Giuseppe

[Georg Pauwen]

Hello,

your network needed a lot of changes/adjustments. You were:

- missing all loopbacks

- missing all WAN (serial interface) IP addressing

- OSPF was misconfigured (or not configured at all) on all routers

Review the attached PT file (saved in version 8), with the changes implemented, and full end to end connectivity.

[Bunny12375]

I tried configuring it at first but it wasn't doing anything maybe i just messed my subnetting and was able to get it working but also thanks for the help!

[paul driver · Accepted solution]

Hello

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@Bunny12375 wrote:

Configure mulit area OSPF and ping successfully from Leg A to Leg B.

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PT is quite restrictive in what feature you can use, however attached is a working PT file with multiple ospf areas along with the a txt file with the configuration applied.

[Bunny12375]

Thanks for this I actually used it as a guide trying to do the homework on my own I appreciate the notes that came along with it!