(no subject)

I think I got your problem can you see the routing table of Router connected
to ISP B, I think it is not able to install default route pointing towards
Router connected to ISP A pls check the ospf external LSA on Router
connected to ISP B for further analysis.

Regards
Nadeem

On Wed, Apr 1, 2009 at 1:23 PM, Zeeshan Sanaullah <
zeeshan_dreamcatcher_at_hotmail.com> wrote:

> hello !
>
> Im stuck in this BGP multihoming Issue , need your help
>
> I have attached the diagram ...
>
> The Organization has been alloted a pool lets say 192.168.128.0/22 from
> the
> RIR like APNIC
> and also it has a public AS.
>
> It peers with two ISPs . ISP A and ISP B.
>
> The Traffic flow must be such as ... all incoming traffic must be preferred
> through ISP A
> except the two pools 192.168.130.0/24 and 192.168.131.0/24 which must be
> preferred
> through ISP B.
>
> For
> this I have advertised 192.168.128.0 /22 to ISP A and the two /24 pools
> to ISP B along with the /22 pool with AS Path Prepended to it.
>
> The Incoming Traffic flow is according to the requirements ..
>
> The problem is with the outgoing traffic.
>
> All outgoing traffic must exit through ISP A except the /24 pools which
> must
> use ISP B.
> This prevents Asymmetric routing.
>
> Both providers send the default route. I have configured ospf between the
> Routers and the
> switch,
> and used the default-information originate command on the routers.
> Router connected to ISP A Advertises the default with metric 20 and
> Router connected to ISP B
> advertises the default with metric of 30 to the L3 Switch
>
> As
> the traffic from / 24 pools must exit ISP B , i configured a Routing
> policy on switch to send traffic sourcing from these pools to ISP B
> which works ..
>
> But the Problem comes when BGP connection to ISP
> B fails. The switch through policy routing sends traffic from /24 pools
> to Router connected to ISP B which now doesnot have the BGP Default
> Route but it has a default route from router connected to ISP A through
> OSPF. The switch and routers are in the same broadcast network.
>
> What
> I see is the problem is that the Router connected to ISP B is not
> sending the same traffic back to same interface because the default
> from OSPF is on the same interface where the traffic is coming from the
> / 24 pools ... is it the right behaviour ?
>
> Do you have any solution to the outgoing traffic requirement using other
> techniques ?
>
> Please Help
>
> Regards
> Zeeshan
>
> _________________________________________________________________
> Quick access to your favorite MSN content and Windows Live with Internet
> Explorer 8.
>
> http://ie8.msn.com/microsoft/internet-explorer-8/en-us/ie8.aspx?ocid=B037MSN5
> 5C0701A
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Wed Apr 01 2009 - 13:31:36 ART