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Community Member

Ospf enterprise to ISP using bgp

Hi all

We have 2 ISP routers from 2 providers, running bgp

I then have 2wan routers running Ospf , these connect to the ISP routers which also run Ospf to the LAN then bgp to the ISPs

What is the best way of pulling the internet traffic from the LAN to theses routers?

My thoughts are run default information originate on the ISP routers, as bgp will have a default route on each Ospf will then use this

Then redistribute Ospf into bgp

Is this the best way?

Would the traffic from the LAN get load balanced to each ISP router?

Am I right in saying without Ibgp between the ISP routers they wouldn't be intelligent enough to pick the closest route per ISP ?

8 REPLIES

Ospf enterprise to ISP using bgp

Well to answer this i have a few questions.

1. Do you have a public network address range that you use?

2. If so, are these Provider Independent (ie you own them and can take them to a different ISP), or are the Provider Assigned(The ISP owns this block)

Do you want to load balance or have an Active/Standby setup?

Ospf enterprise to ISP using bgp

Hello, Carl.

I agree with John - could you please share network diagram including IP-addresses per link (interface) and LAN?!

If you are using pribvate addresses somewhere, then what device[s] is doing NAT?

Community Member

Ospf enterprise to ISP using bgp

I would like to load balance

we have our own AS and PI block and are provider independant

firewall behind the devices are doing NAT and will point to a hsrp address of the wan routers

Ospf enterprise to ISP using bgp

Carl,

So just to be sure, your LAN routers (The ones you own), are your firewalls connected directly to these two routers, and what are the addresses that these are all connected to? Are they on the same broadcast network? Please feel free to put dummy IPs to hide your real ones

Community Member

Ospf enterprise to ISP using bgp

Hi

Yes the firewalls are on the same subnet as the routers' they are all using public addresses

On the firewalls we point the default gateway to the hsrp address of the routers

Look forward to your replies

Ospf enterprise to ISP using bgp

Car;,

The firewalls are on the same subnet as the routers?

So does your topology look like this?

ISP1 ISP2

|               |

R1         R2

|                |

  (Firewall)

        |

(Local Area Network)

Community Member

Ospf enterprise to ISP using bgp

Yes that is correct

Ospf enterprise to ISP using bgp

Carl,

Sorry for all the questions. This part just confused me a little bit.

What is the best way of pulling the internet traffic from the LAN to theses routers?

My thoughts are run default information originate on the ISP routers, as bgp will have a default route on each Ospf will then use this

Then redistribute Ospf into bgp

What is the best way of pulling the internet traffic from the LAN to theses routers?

You could run 'default information-originate' command with OSPF, and have OSPF on your firewall (depending on how well this works). If you receive a default route via your eBGP neighbor from your ISP, then if your eBGP peer to ISP2 were to go down, this will not have the default route anymore, since it won't be listed, and OSPF should remove this.

You could configure two static default routes on the firewall, but if one ISP goes down, I"m not sure how this will affect the firewall, this would depend on the make and model.

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