topic Re: Single Area OSPF Netzwork in Switches, Hubs, and Modems

Single Area OSPF Netzwork

Tobias Schuhmacher — Wed, 02 Aug 2006 11:39:54 GMT

Hi there!

I am looking for someone helping me with my procurve configuration problem. Unfortunately the German procurve support was not able to help me what so ever and they suggested me to try it in this forum. So I did:

I have a 5406cl (Switch A) with a Premium Edge Licence and a little 3400cl (Switch B). They both support OSPF. What I want to configure is the following:

Switch A located in building X has the IP 10.0.6.1/8, Switch B located in building Y is configured with the IP 10.0.6.2/8. Both Switches are connected directly over Port 1 via a laser/fiber-to-100BT connection (meaning an almost normal LAN 100Mbit connection). As a backup (if the laser connection brakes) I connected both Switches with Port 2 on an ISDN-Router running an ISDN leased line.

Now I want to use the OSPF protocol to provide the following scenario:

All my clients in building Y are working on a terminal server located in building X over the fast 100MBit Ethernet connection. But when there is a problem with that line I want all the network traffic to get redirected (in max. 30 seconds) through the second connection Port 2.

Maybe there is someone out there able to help me, it would be so wonderful!

I give you a list of the configuration commands I used:

Switch A:

Switch_A# con
Switch_A(config)# vlan 10
Switch_A(vlan-10)# untag A1
Switch_A(vlan-10)# ip address 10.0.6.10/8
Switch_A(vlan-10)# vlan 20
Switch_A(vlan-20)# untag A2
Switch_A(vlan-20)# ip address 10.0.6.20/8
Switch_A(vlan-10)# exit
Switch_A(config)# ip routing
Switch_A(config)# router ospf
Switch_A(ospf)# area 0.0.0.0
Switch_A(ospf)# area 0.0.0.1
Switch_A(ospf)# redistribute connected
Switch_A(config)# vlan 10
Switch_A(vlan-10)# ip ospf area 0.0.0.0
Switch_A(vlan-10)# vlan 20
Switch_A(vlan-20)# ip ospf area 0.0.0.1
Switch_A(vlan-20)# exit
Switch_A(config)# write run
Switch_A(config)# boot

Switch B:

Switch_A# con
Switch_A(config)# vlan 10
Switch_A(vlan-10)# untag 1
Switch_A(vlan-10)# ip address 10.0.6.30/8
Switch_A(vlan-10)# vlan 20
Switch_A(vlan-20)# untag 2
Switch_A(vlan-20)# ip address 10.0.6.40/8
Switch_A(vlan-10)# exit
Switch_A(config)# ip routing
Switch_A(config)# router ospf
Switch_A(ospf)# area 0.0.0.0
Switch_A(ospf)# area 0.0.0.1
Switch_A(ospf)# redistribute connected
Switch_A(config)# vlan 10
Switch_A(vlan-10)# ip ospf area 0.0.0.0
Switch_A(vlan-10)# vlan 20
Switch_A(vlan-20)# ip ospf area 0.0.0.1
Switch_A(vlan-20)# exit
Switch_A(config)# write run
Switch_A(config)# boot

Waiting and hoping for an answer...

Toby

Re: Single Area OSPF Netzwork

Mohieddin Kharnoub — Wed, 02 Aug 2006 12:30:03 GMT

Hi

1- You have configured 2 areas in your configuration, Area 0 and Area 1 on both Switches , and NOW your OSPF processing is CONFUSED ... Where is Area 1, is it in Building X or in Building Y. :)

2- You have configured basically 3 Networks, one is WAN, and 2 LAN on both sides, and all these Networks have the Same IP address Range ??? Is it possible ???? if yes, then no need for routing .....

3- If you fixed the IP addressing, i can break out the configuration for you, its simple:
Since you added Redistribut Connected, then this command will Distribute Vlans on both sides to other OSPF router ONLY After you fix the IP addressing.

4- Consider now we have a perfect Network with WAN link and OSPF working fine, you just need to enable Spanning Tree - MSTP because you have a loop between Ports 1 - Laser Link, and 2 - he ISDN , and Then :
Adjust the Port Priority or Path Cost for port 2 so it will be Blocked by MSTP.
And in case of Failover on the Laser Link ( Port1), then MSTP will enable the ISDN port2 in less than 2 Seconds.

And now you have a redundant Network.

Check this similar case :
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1042134

OSPF Configuration Example:
http://www.hp.com/rnd/support/config_examples/5300xl_ospf_singlearea.pdf

Last thing, if you need help in the Configuration after all, let us know.

Don;t forget to assign points :)

Good Luck !!!

Re: Single Area OSPF Netzwork

Mohieddin Kharnoub — Wed, 02 Aug 2006 13:44:15 GMT

Hi

The attached file has your configuration, i have changed the IP addressing to complete the configuration , Vlan 10 will be 10.0.1.x/24 , and Vlan20 is 10.0.2.x/24 and Vlan30 is 10.0.3.x/24.

You change then it to the Range you want , AND please check the Configuration because NO One Perfect :)

Good Luck !!!

Re: Single Area OSPF Netzwork

Tobias Schuhmacher — Thu, 03 Aug 2006 05:18:13 GMT

Hi Mohieddin,
Thank you for your help, I really appreciate it!

1- I see what my problem was. I changed it to only one area 0.0.0.0 (Backbone)

2- Because of the routing problem I have changed my network address in building B to a class C network (10.0.10.0/24).

I attached my network topology as a PDF file. Please tell me whether Iâ m on the right way or not and if possible provide a configuration for both switches.

I am really indebted to you! (max points ;)

Toby

Re: Single Area OSPF Netzwork

Mohieddin Kharnoub — Thu, 03 Aug 2006 08:15:24 GMT

Hi

The map was helpful, anyway i made the necessary configuration for you to run OSPF + RSTP with redundancy.
I changed the Laser link IP address to 192.168.1.0/24 range, anyway it won't affect you , and i enabled Spanning tree, so it will Restart your switches, so the configuration is:

--------------------------------------------
Switch A:

5406# con
5406(config)# vlan 10
5406(vlan-10)# untag A1
5406(vlan-10)# ip address 192.168.1.1/24

5406(config)# ip routing
5406(config)# router ospf
5406(ospf)# area 0.0.0.0
5406(ospf)# redistribute connected

5406(config)# vlan 10
5406(vlan-10)# ip ospf area 0.0.0.0

5406(config)# span -- enable spanning tree
5406(config)# span priority 0 -- force ROOT bridge
5406(config)# wri mem
--------------------------------------------
Switch B:

3400# con
3400(config)# vlan 10
3400(vlan-10)# untag 1
3400(vlan-10)# ip address 192.168.1.2/24

3400(config)# ip routing
3400(config)# router ospf
3400(ospf)# area 0.0.0.0
3400(ospf)# redistribute connected

3400(config)# vlan 10
3400(vlan-10)# ip ospf area 0.0.0.0

3400(config)# span

3400(config)# wri mem
--------------------------------------------

Note:
I removed unecessary config to run this setup, and later you add any vlans you want. :)

Please check after me, no one is perfect.

Good Luck !!!

Re: Single Area OSPF Netzwork

Tobias Schuhmacher — Fri, 04 Aug 2006 04:05:40 GMT

Thank you again my helpful friend. Finally it worked for me! The only thing that I changed is that I added up the second ports (5406zl Port A2 and 3400cl Port 2) to the vlan 10 and everything was working fine. Now when I unplug the cable from the first port the switch starts to route all the traffic over the second port. After I plug in again the switch toggles back to the first port in less then one second. Perfect! Thank you so much!

Just another thing which I where considering: What happens if I let my two routers running the backup ISDN leased line as being bridges - meaning both switches would be in the same ip subnet - is a failover from port 1 to 2 and back possible as well? Do I need OSPF to set this up or will be RSTP alone just fine for me? But how would I tell the switch that port 1 has lower costs then port 2?

Looking forward to your answer. Rating as usual ;)

Toby

Re: Single Area OSPF Netzwork

Matt Hobbs — Fri, 04 Aug 2006 09:50:48 GMT

If you did configure the ISDN Routers to bridge only, then you would need to either assign a lower spanning-tree port priority or cost on the A1 links to ensure they take that path.

e.g.
span a1 pri 1

With your current configuration I don't think that STP is actually doing anything since the ISDN Routers are not bridging. If you do a 'show span' on both ProCurves, you will probably see that A1 and A2 are both forwarding.

Right now with OSPF it is preferring the laser link as it has the lowest OSPF cost since it has a direct connection with the other ProCurve and does not have go via the ISDN Routers which increases the past cost.

In a real life scenario, it is more likely for the link between the lasers to fail. With OSPF this means that the failover will be more like 40 seconds, compared to only 1-2 when you pull the cable from the port. This because it now relies on the Hello packets to determine that link is not available. When you pull the cable from the port the switch knows immediately that the link is down so can quickly failover.

You should be able to improve this by lowering the OSPF timers.

On the other hand, with spanning-tree on default settings it should be closer to 2 seconds for a failover of any type.

I don't think either method is really better than the other, each have their advantages. Right now if it is working and you are happy with it, I would leave it that way.

Re: Single Area OSPF Netzwork

Mohieddin Kharnoub — Fri, 04 Aug 2006 11:10:29 GMT

Hi

Matt, for port priority, Lower port number has always Higer Priority and thats why i didn't guide him to change port A1 priority on the 3400 and A2 will be blocked by STP.

For the ISDN router, he said "As a backup (if the laser connection brakes) I connected both Switches with Port 2 on an ISDN-Router running an ISDN leased line"

So with the 5400 and 3400, how we can configure an ISDN backup connection ?

1- as you suggeted by using the ISDN routers as bridging, so the ISDN line always active, and blocked by the STP on 3400 port A2, and in this solution decreasing the hello time will get us faster convergence, but call cost arise here.

2- Use Static routes with different administrative distance, so when the Laser link fails, the ISDN routers will be triggered to initiate a call and provide failover.

So do you think Matt creating another OSPF area to include the ISDN wan link, and add 2 static routes on the 5400, first one with AD=1 and points to A1 subnet on the 3400, and the other Static route with AD > 1 points to A2 subnet on the 3400, so if Laser link failed, the 5400 will use the second static route to get to 3400 ??????

Is that a good suggestion ?

Re: Single Area OSPF Netzwork

Matt Hobbs — Fri, 04 Aug 2006 19:08:45 GMT

If the ISDN routers are also running OSPF in Area 0 it should be working already. My assumption is that the leased ISDN line is permanently up.

The 3400 I don't believe you can set the administrative distance for a static route. I also think for a static route like that to work, the physical link between the laser and the 3400 would have to go down and that port could only be on the one VLAN. Otherwise it will still assume that network is up and will keep trying. What you really need in this type of setup is Uni-directional Link Detection.

In this setup, I would try and avoid using static routes. Either rely on OSPF, or set the ISDN routers to bridge and use spanning-tree only.

If the leased line must dial a connection each time when the backup is to be made, use OSPF.

Re: Single Area OSPF Netzwork

Mohieddin Kharnoub — Sat, 05 Aug 2006 00:39:03 GMT

In fact, its true that ISDN leased lines are always active, so ISDN routers should be in bridging mode, hence for Faster solution its better to use Spanning Tree if ISDN routers in bridging Mode.

It means the best Scenario is :

- Enable Spanning Tree on both switches, and change priority of 5400 to be the Root.
- 3400 port A1 will be in forwarding using laser link.
- 3400 port A2 will be blocked, but ISDN routers are ready and isdn line is active.
- If the laser link failed, MSTP will enable port A2 on 3400 and the network will be back on.
- For internal routing on both sides, continue to use OSPF, but in this case, the WAN links (Laser and ISDN) should be in the same Network or subnet.

What do you think ????

Re: Single Area OSPF Netzwork

Matt Hobbs — Sat, 05 Aug 2006 03:50:07 GMT

I agree, it probably is the best solution to use spanning-tree and set the ISDN routers to bridge. It should be faster to failover and it's easier to setup and troubleshoot.

One other advantage is that if you're using protocols other than IP, it will carry them as well.