OSPF Routing Problem

[wasiimcisco]

I am facing problem in Routing in between head office and DR (disaster recovery) Side.

I have two links to my DR Side. I have GRE Tunnel with Primary and Secondary Router located in head office.

I want DR to use the Primary Router (tunnel 550) as primary link and Secondary IPVPN Router (Tunnel 540) as backup.

But I am not able to achieve this. I have even shut down the GRE tunnel (540) on Secondary IPVPN Router but still the traffic is going through this link. I am not able to track which path the traffic is taking. My bandwidth graph is high on on Secondary IPVPN link and Hardly few kbps is being used on the primary IPVPN link.

This means that something is wrong with the routing. Please go through the configuration and let me know what i am missing and which link cost I need to modify in order to use exact require link.

[wasiimcisco]

Hi,

Please see the ouput from DR router.

         
ENOC_DR_R01#show ip ospf database external 192.168.200.0

            OSPF Router with ID (172.27.1.10) (Process ID 1)

                Type-5 AS External Link States

  Routing Bit Set on this LSA
  LS age: 1775
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 192.168.200.0 (External Network Number )
  Advertising Router: 192.168.0.162
  LS Seq Number: 80000440
  Checksum: 0x38D2
  Length: 36
  Network Mask: /24
        Metric Type: 1 (Comparable directly to link state metric)
        TOS: 0
        Metric: 20
        Forward Address: 192.168.0.43
        External Route Tag: 0

=========================================================================================

ENOCDC_R04#show ip route 192.168.200.0
Routing entry for 192.168.200.0/24
  Known via "static", distance 1, metric 0
  Redistributing via ospf 1
  Advertised by ospf 1 metric-type 1 subnets
  Routing Descriptor Blocks:
  * 192.168.0.43
      Route metric is 0, traffic share count is 1

===============================================================================================

Further to clarify myself in this case ENOCDC_R04 is ASBR ??????. External cost in DR router showing 20 and Tunnel 550 cost on DR Router is 10.

DR point of view  , Go to 192.168.200.0/24

External Cost 20 + Cost to ASBR ( which will be tunnel 550 cost 10 on DR Router) + ASBR LAN Cost (R04 gig 0/1 cost is 30)

That is why it is showing 60 Cost. Correct me if I am wrong.

======================================================================================================

In case of DR is using Tunnel 540 for sending traffic then the cost will be like this

DR point of view  , Go to 192.168.200.0/24

External Cost 20 + Cost to ASBR ( which will be tunnel 540 cost 20 on DR Router) + ASBR LAN Cost (R03 LAN interface gig 0/1 cost is 30)

20+20+30=70

Correct me If I am wrong.

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hi,

   I forgot that Gig0/1 is running OSPF as well. We need to add LAN cost for O*E1 routes. If you didn't set the metric when doing redistribution you should see metric 20 from "show ip ospf database external".  You can check ASBR by using "show ip ospf border-router" on DR router.

  So you're correct 5-point. Good Job!

Toshi

[wasiimcisco]

Hi,

Thanks for the continous support and follow up. Things are working fine now. If i will face issue i will get back to you.