[c-nsp] BGP Backdoor Links Problem

Manu Chao linux.yahoo at gmail.com
Wed Oct 14 06:50:05 EDT 2009

You needn't BGP Backdoor option

Prefer BGP Communities, easier, better
On Mon, Oct 12, 2009 at 4:08 AM, Fossett, Jeff S
<Fossett.Jeff at con-way.com>wrote:

> Hi Team - figured most of you could provide a fix for the following
> scenario in your sleep, so I thought I'd reach out.
> We have a Primary DataCenter and a DR Facility, attached via MPLS privately
> (using EIGRP across that link to peer the two DataCenters)... both also have
> an eBGP Peering Relationship with a Service Provider that is providing a
> private Cellular APN.   Though both connections are "Active" to the Service
> Provider Cellular PN, we want an "Active/Standby" type of routing scenario.
>  Our DR Center is not built up in a manner that adequately supports
> Active/Active from an Application/Middle Tier/Mainframe standpoint.
> Scenario:  In our BGP peering relationship with the ISP (giving Cell
> Services) we are running eBGP.  Whenever routes are learned with eBGP they
> have a local cost of 20.  Since our "DataCenter Gateway" is getting the
> routes to the cell private networks from eBGP via "DR Gateway" they are
> always preferred over the Portland learned EIGRP external routes with a 170
> cost.  When peering to the cell carriers is active in both the DataCenter
> and DR, the data sourced or destined for DR from the cell carrier networks
> will fail.
> Problem:  We used the BGP Backdoor option on the DataCenter gateway to
> change the distance on the Cellular Cloud networks from 20 to 200 in order
> to allow our DataCenter gateway to prefer EIGRP routes within the DataCenter
> environment, and then redistribute into BGP.
> But once we put this in, BGP no longer advertises any networks that are
> associated with the backdoor command.  Should we pursue some sort of
> Conditional Advertisement, or Synchronization/Redistribution scenario???
> Any advice?  Thanks so much in advance for the help . . .
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