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New Member

Two E3 in two diffrent site without Opening OSPF

I have two E3 access links terminated on two Cisco 2811 routers (Main & Backup)

I am using the OSPf as a routing protocol.

I need one branch to talk to both links (Active PVP and Standby PVP), the problem is that I can not open the OSPf on the ATM interface of the two routers because of the security, it is connected to a third party network (external network).

How I can do that, is there any way around

Many thank.

8 REPLIES
Silver

Re: Two E3 in two diffrent site without Opening OSPF

If you cannot enable OSPF (or dynamic routing protocol), you can use static route and redistute it into OSPF at main and backup routers. During the redistribution, you may consider to control the route between main/backup and remote that the main is the preferred path to the branch.

However, you have to ensure the external network provider can carry the correct routing and the connectivity for you.

Hope this helps.

Hall of Fame Super Silver

Re: Two E3 in two diffrent site without Opening OSPF

Majed

I am not sure that I understand your problem or maybe I just do not understand your topology? Perhaps you can help me understand it better?

If you have two routers that are connected by a direct E3 link (are on a common subnet) and could run OSPF, then I find the concern about a provider in the middle hard to understand.

Perhaps one alternative would be to configure a GRE tunnel between the two sites and run OSPF over the GRE tunnel. And if security is a real concern then perhaps an alternative could be an IPSec with GRE tunnel to encrypt and protect traffic going over the link.

HTH

Rick

New Member

Re: Two E3 in two diffrent site without Opening OSPF

Dear Rick,

Attached is the exact topology I have, I hope this will demonstrate my network better.

I have tried to use the redistribute static but it didn't work properly for some reason

Silver

Re: Two E3 in two diffrent site without Opening OSPF

According to the diagram, do you mean the standby site is cold standby ? If not, why is it using same IP of main site ?

I expect you will have two PVCs, one from branch to main, and one from branch to standby.

Please advise will the main and backup to communicate to each other ? If yes, it will require one more PVC between main and backup.

Please clarify and seems there is an issue.

Please also advertise which redistribute static problem you got.

Hope this helps.

New Member

Re: Two E3 in two diffrent site without Opening OSPF

yes it is cold standby, it is not active unless the first E3 link goes down, it is fasilty from our ISP.

The two sites A & B already connected to each other and having another E3 PVP 7MB link

New Member

Re: Two E3 in two diffrent site without Opening OSPF

This diagram clear the two sites link

Hall of Fame Super Silver

Re: Two E3 in two diffrent site without Opening OSPF

Majed

I have looked at your diagram and I have re-read your original post and I am still somewhat confused.

I do now understand that you have a primary site and a backup site. Given that the backup site appears to have different IP addressing than the primary site, I am confused why the E3 connection has the same IP address at both sites and I believe that this causes difficulty in what you are attempting to achieve. Can you explain the reason for configuring this? And whether it would be possible to change this part of the implementation?

Since both destination routers over the E3s have the same IP address it might be helpful if you could post the configuration of the router that connects to both of the E3s (the remote router3).

HTH

Rick

Silver

Re: Two E3 in two diffrent site without Opening OSPF

If site B is cold standby site for the WAN connection but inter-connection to site A is active. Do you mean if the site A WAN down, the traffic from remote will flow to site B then site A server ?

It is working in principle, but why site B is cold standby ? How do you redirect the link from site A to site B if site A WAN down ?

Will the remote site have dual PVCs, one to site A & one to site B ? If yes, it is better to make site B as warm standby and different WAN IP to site A.

If both sites are up then you can setup two static routes for site A/B server and two floating static routes for site B/A to backup each other at remote site. At site A/B, just setup one static route to point to remote site and redistribute it to the OSPF to tell other routers how to reach remote.

Could you please clarify the traffic flow in normal case and site A/B WAN down case ?

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