Hello,
Currently we have a 50mb pipe with our carrier SONIC. We have signed another contract with another provider here in town (Charter) to multihome our Internet connections in an active/active configuration. We have leased our /24 space through our carrier SONIC. ARIN has already approved our org-ID for an ASN and they will be sending us that once the billing portion is finished.
There a few design considerations I was hoping I could get some insight from the community on.. Before I start, the ultimate goal for us to use BOTH Internet connections in an active/active configuration - utilizing both pipes..
Disclaimer: I have gathered this design from a lot of other posts that have somewhat of a similiar topology with ASA-->3750-->router pair-->CPE--internet.. Please keep an open mind if you think im on the wrong track..
Please see the attached design topology.
Questions related to design:
- What kind of routes should I get from each carrier? I have been told that partial/partial routes plus a default route form each carrier is the way to go. Also, I've heard mention that full routes from both carriers are preferred. My ASR1001's can support ~500k routes. I know the global table is approximately ~337k routes. My goal is to use both pipes and use the best outbound path per carrier.
- We will be leasing our /24 space from SONIC. I plan on running OSPF on the DC-Edge-SW1 in conjunction with iBGP - so I can default originate two equal cost routes back to my ASA. My confusion is when the traffic hits DC-Edge-SW1, there will be default equal-cost iBGP routes to both ASR1001's (DC-Edge-RT1 & DC-Edge-RT2). If the switch does not have the BGP table, it will just load-share across both ASR's. When the traffic hits the ASR's, will they know which carrier has the best path and route accordingly?
- Should the iBGP connection between both routers be directly connected ? Or will it suffice through the L3 3750 connection? Also, with the limitations on the routes for the ASR1001 at ~500k. If we end up getting full routes from carriers and create a iBGP neighborship between both routers, will this exceed the route limitations on this platform?
- On both routes, I will have the network statement 'network 12.231.69.0 mask 255.255.255.0.' This is a leased network from SONIC, and we NAT everything on our ASA to 12.231.69.10. My question is, will this be a problem broadcasting this network from our AS to both carriers AS?
- Refer to bgp-design.jpg - is it a requirement that I use our leased public subnet 12.231.69.0/24 for the interfaces from ASA5510 -> 3750 -> ASR1001?
Thank's in advance for any assistance/insight you can provide as this is the most advanced topology I have worked with.
