Hi,

First off lets clear up to things:

OSPF is an igp protocol, you would use it to share routes between your 
own routers not a transit providers.
iBGP is again an igp, this time BGP will automatically talk iBGP when 
talking to routers within the same AS. Your BGP sessions will 
automatically talk eBGP to your transits.

Ok so lets look at the way it will need to work, BGP works by 
propagating the routes you announce to your  up stream 'transit' peers, 
via eBGP. In turn these transit providers announce your routes to the 
larger internet. Remote AS's will choose a path back to you based on 
several factors inc. AS path length,  local preference, weighting etc.

You can control to some extent the provider your inbound traffic arrives 
on by padding your announcement to one provider over another, outbound 
traffic is much easier as you can use various methods of setting local 
preferences based on inbound communities etc.

Now this is all great in theory however to do this with two providers 
you will need your OWN AS, this is necessary as the transit will simply 
filter out any private AS's (65xxx).

You will also need your own reasonably large IP allocation. From your 
diagram I see you are using a /28 how did you come by this? If this was 
given to you by a provider e.g. ISP1 they will already be announcing 
this as part of a summarised route to their transits, as such they 
probably won't let you re announce their allocation to ISP2. Even if 
this IP space has been allocated to you e.g. by ripe many transit 
providers are now filtering out smaller routes such as /24 routes, let 
alone /28 in an effort to keep their routing tables to a minimum. See 
below we're now at about 260k routes! So in this case even if ISP1 & 2 
re transmit your routes their upstreams will filter you out so you won't 
get connectivity.

Now I'm no BGP expert by any means so please forgive me if any of this 
is wrong or misleading.

Out of pure 'play' factor I do maintain a BGP peering session with one 
of my ISP's from a OpenBSD 4.3 box, I usually use Cisco so wanted to 
play OpenBGP.

# bgpctl sh sum
Neighbor             AS       MsgRcvd    MsgSent    OutQ  Up/Down  
State/PrfRcvd
MT Peering           13122    183343     3245       0     2d06h03m 263451
#

I would suggest your best bet is to follow the good advice of others and 
look at the multi homed solutions suggested.

Hope that helps

Simon

 



BARDOU Pierre wrote:
quoted text
> Hello,
>  
> I am trying to set up a configuraion like this :
>  
>              +------- -+       +---------+ 
>              |  ISP1   |       |  ISP2   |     Cisco
>              | ROUTER  |       | ROUTER  |
>              | AS3215  |       | AS12670 |
>              +---------+       +---------+
>                   |                | 
>                   |                |
>              +---------+       +---------+ 
>              |   BGP   |       |   BGP   |
>              | ROUTER  |       | ROUTER  |     OpenBSD 4.3
>              | AS47818 |       | AS45818 |
>              +---------+       +---------+
>                   |                | 
>                   |                |
>              +-------------------------+
>              |    217.109.108.240/28   |
>              +-------------------------+
>                   |                |
>                   |                |
>              +--------+        +-------+
>              |   FW   |--------|  FW   |       OpenBSD 4.3
>              | MASTER | pfsync | SLAVE |
>              +--------+        +-------+
>                   |                |
>                   |                |
>              +-------------------------+
>              |     PRIVATE NETWORKS    |
>              +-------------------------+
>  
> I'd like to load balance outgoing connections to the internet,
> but I don't know how to configure openBGPd to do this.
> I searched a lot on the Internet and I found a lot of informations 
> on how to do this with cisco, but I have never found an openBGP solution.
> Some people speak about it but I have never seen it.
>
> I made a test conf where failover works like a charm (using iBGP on the 
> FW's with 'set nexhop self' on BGP routers), but when both connections 
> are active only one is used.
>
> Would it be possible to help me please ?
> Is setting up iBGP sessions between FW's and BGP routers a good idea ?
> Should I rather use OSPF for this ?
> And in tha case how to configure it to loadbalance/failover ?
>
> Many thanks
>
> PS : loadbalancing incoming connections too would be very nice, but I 
> understood it was much more difficult.
>
> --
> Cordialement,
> Pierre BARDOU