ISP Failover with Default Routes. Whats my best options?

[pcovell74]

The company that I work for has grown dramatically. We either buy or build new offices every other month it seems like. Just recently we have added a remote Colo facility to our network infrastructure with its own Cisco ASA firewall and DIA circuit. The plan is to move the majority of the critical servers over to the Colo facility and have it as the default route out.

Both the Colo and Houston office consist of a Cisco ASA 5545-X, HP Aruba Core Switches, Cisco 3900 series Routers, File servers, Web servers, Exchange servers,Content Filters, Etc. Our Houston Office also consist of about 400 employees

The remote offices consist of Cisco 1941 Routers, HP Procurve Switches, File Servers, and about 20 -30 employees each. Currently all offices route to each other via BGP over Level3's MPLS Network and the default route going our through the Houston office

We need to advertise a default route to all of our remote offices to the Colo first with failover to the Houston office just in case. My thought was to setup IP SLA Tracking at all the remote offices. Have 2 default routes, primary being the Colo Route and the Houston Router being gateway of last resort.

Then I was going to setup IP SLA tracking on both the Colo and Houston routers. Both finding the best path out the DIA circuits and each having a local default route. That way if say internet goes out at the Colo, traffic is still routed to the Houston firewall. If the remote users need to access Houston servers and the Houston MPLS circuit goes down, they can still route through the future 10G wave fiber.

I guess my question is this, is there a better way to do this than what I currently have planned?

[Julio E. Moisa]

Hi

If they are different locations, You could redistribute/advertise a default route from the edge routers with different metrics. If you are using OSPF, Colo's router could be advertise the default route to other peers like:

Colo

router ospf X
default-information originate (always optional) metric 10

Houston

router ospf X
default-information originate (always optional) metric 20

The lowest metric will be always preferred, if you are using BGP you could use a similar scheme like OSPF.

Hope it is useful

:-)

[Collin Clark]

I would not use IPSLA, too many things to go wrong cause routes to move when not necessary. Keep it simple and let the routing protocol do it's job. Julio is spot on.

[paul driver]

Hello

Your diagram is showing that San Antonio and Austin are trransit sites for Dallas.
You say your also using BGP.

Given the above topology - Are all 3 sites IBGP peers to each other and is SA and Austin Ebgp peers to the main offices?

If this is the case then utilizing local preference bgp path attribute for any advertised routes to the spoke sites would be applicable in this case.

If you are also using IGP such as what Julio stated (ospf) you have quite a few options to advertise a preference path depending on the opsf area or metric types etc..

1) metric value ( if using the same metric type)
2) ospf cost ( interlace or area)
3) metric-type ( type 1 is preferred over type 2)
4) max-metric router-lsa on the less preferred ospf rtr at main office ( this will increase cost values from that rtr so that its less preferred

res
Paul

[pcovell74]

I have updated the topology so there is no confusion.