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Re: Redundant Routes, BGP with MPLS provider
From: PC <paul4004 () gmail com>
Date: Fri, 31 Aug 2012 11:29:36 -0600


1) Ask the provider if they have any traffic engineering communities
available.  Many of the large ones offer some.
2) Use BGP MED to influence the output path (works in most cases).
3) If that fails, use as-path pre-pending to influence the output path from
the provider towards you.

GRE tunnels are not necessary for MPLS in most use cases.  Additionally,
many SPs support native multicast over their L3VPN services if you need
this -- shop around.

Finally, you mention the vendor can accept traffic on either router.
Consider just announcing the routes equally from both locations into MPLS
and letting the traffic more or less load balance as it sees fit on the way
to your vendor -- this is how the internet generally works.

On Fri, Aug 31, 2012 at 11:18 AM, Blake Dunlap <ikiris () gmail com> wrote:

I'd prefer to trust / get the provider to do the right thing over losing
the 40 mtu points.... and all the associated headache therein.


On Fri, Aug 31, 2012 at 11:33 AM, <Bill.Ingrum () t-systems com> wrote:

I work for an MPLS provider, so I guess I tend to trust them ;)


-----Original Message-----
From: Lee [mailto:ler762 () gmail com]
Sent: Friday, August 31, 2012 11:28 AM
To: Ingrum, Bill
Cc: WTribble () sterneagee com; nanog () nanog org
Subject: Re: Redundant Routes, BGP with MPLS provider

On 8/31/12, Bill.Ingrum () t-systems com <Bill.Ingrum () t-systems com> wrote:
I think having a GRE tunnel for the internal routing protocol is

It might be, but we have a requirement for multicast over the wan so the
GRE tunnels had to be there.

 Can you explain the reasoning behind this?  I understand the
technical issue whereby GRE will allow multicast for EIGRP, OSPF, etc,

but why not just redistribute into BGP?

I see no reason to trust the provider that much.

I work on a lot of MPLS CE routers, and in general you can accomplish
anything you need by redistributing your internal routing protocol
into BGP, and adjusting LP, MED and AS Prepend as needed.

Sure.. but how do you *know* you're not getting anything added/removed
by the provider?




-----Original Message-----
From: Lee [mailto:ler762 () gmail com]
Sent: Friday, August 31, 2012 11:15 AM
To: Tribble, Wesley
Cc: nanog () nanog org
Subject: Re: Redundant Routes, BGP with MPLS provider

On 8/30/12, Tribble, Wesley <WTribble () sterneagee com> wrote:
Hello all,

I am an Network Operator working in an Enterprise environment with
offices all over the country(mostly connected via MPLS).  We are
currently working towards building a Disaster Recovery Site that will

host some of our vendor routers and provide the capability to access
these vendors from both our primary and backup data center locations.

The routes(as advertised by the vendor's routers) will be the same at

both locations.  I would like to advertise the routes from multiple
locations at the same time, rather than suppress the routes and
advertise conditionally.

At work, we have our internal routing protocol running on GRE over
IPSec tunnels & keep the BGP sessions with the MPLS provider limited
to just the MPLS network.  And have an ACL on the MPLS network
interface that allows only what's expected in...   some providers are
better than others at not having anything hit the 'deny any any log'


What is the best method to Instruct the provider's network to prefer
the Primary Data Center routes over the DR site?  Keep in mind that I

am only peering with the provider over BGP and I have no visibility

the underlying MPLS architecture or configuration.  Although if you
have specific questions  about their architecture, I can work to get

Discussing in house, we have gone over a few different options:

-Advertise specific routes from primary site and summary routes from
the DR site.  Most specific will always be chosen.
-Prepend the routes from the DR site so that they will have a longer
AS-path than the Primary location -Use Community Strings to influence

local preference.(Still working to find out if Provider will pass our

community strings)

Just looking for some ideas and best practices.  Any thoughts or
insight would be much welcomed and appreciated.  This is my first
message on NANOG, so please be gentle.  I apologize in advance if I
have done something incorrectly.


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