Default routing in a MPLS cloud

[miwitte]

I am new to MPLS so I don't have a complete understanding on how things work in the cloud. We have a connection to another company using a MPLS cloud. Our initial connection is a BGP peer to the MCI cloud and we advertise our networks and the other side advertises their networks. The one thing we do not advertise is the 0/0 route because we don't control the other router and we are afraid that if something is not configured properly, their default will be through us. We are bringing up another company through this cloud and all their traffic will need to come through us, so they need a default (0/0) to us. Of course the easy way would be to advertise 0/0 into BGP and propagate to them. Since we have the restriction about sending 0/0 to the other company, I wanted to use a static default pointing to one of our advertised routes. My concern is that the MPLS network won't know anything about the default and drop it. Or is that not a issue since the path is defined using labels? My understanding is that only my edge router that connects to the edge LSR needs to know how to get to the default. Once it gets to the edge LSR, it will use tagging to transport the packet to the far side LSR. Is this correct?

[romccallum]

you shall have to get your SP to configure default-information originate on your bgp connections.

[miwitte]

If I am using a default on the spoke site to one of the networks on the hub we are advertising , wouldn't that work? My understanding is that once the packet gets into the MPLS cloud it uses tagging to route the packet back to our hub site. If not we will just advertise 0/0 using default originate.

[romccallum]

nope the SP will drop the default route unless specifically asked to transport it. I know Im a SP ;-)

[miwitte]

so do they need to accept the default route from us on the hub side and also on the spoke side? Also would just using a static default route on the spoke site to one of our routes on the hub site work? We redistribute our internal networks to BGP so they will get advertised to our other sites.We will be doing this at a remote site in a couple weeks and I don't want any suprises. Thanks for the info so far.

[romccallum]

yes that is the case. I have a customer for instance who attaches to 10 PE routers. On three of those PE routers I am receiving a default route from 3 CE routers. When they first tried this the default would get to the PE router but would never be transported across the MPLS network....until that is I allowed BGP to transport it.

[miwitte]

So I only need this for the default 0/0 route inserted into BGP right? The other routes will be propagated to all of my PE routers? The next question I need is will a static default on my spoke router pointing to a route on my hub work or will I need to insert the 0/0 into BGP? Thanks!

[romccallum]

if you want the static default route to be propogated to your spoke sites then yes you will still need what I described above.