Good Morning,
I have been given the recent task of rebuilding a multinational enterprise network. The previous architect created a lot of problems by doing mutual two route redistribution between several protocol in several areas causing a lot of instability. We resolved instability with a lot of complex routing policies I am not comfortable with. The decision has been made to re-architect the whole network.
This network has five "major sites" each one of these sites have a pair of ASRs. The ASRs are connected in a ring and form a MPLSL3VPN backbone supported in house. One VRF will be configured to two links to a downstream "core" at each site. So like this:
R1-PE-Site-A---mpls-----R2-PE-Site-A---mpls---R1-PE-Site-B----R2-PE-Site-B-----...and so on
Each site is like this:
R1-PE-Site-A---MPLS----R2-PE-Site-A
| |
site A core R1-----------site a core R2
Fortunately the MPLS backbone was done well and is stable, and for now will stay in place. The task has been given to rebuild the major sites with one protocol and remove all the redistribution within the sites causing the problem. Long story short I am trying to figure out the "best " PE-CE routing protocol to use. The sites will all run OSPF as an IGP due to multivendor. Right now, I like the idea of running OSPF as PE-CE because of the downward bit preventing loops automatically. But I also like the idea of running straight BGP since it is native and I can control path selection way easier. AS path loop prevention is nice as well. Myself and the team supporting is comfortable with both protocols.
Also I would like to point out that each one of the major sites has a provider managed dual connected MPLS hub. We control the CEs at the hub that connect the provider MPLS via BGP CE-PE. And I am worried about the downward bit on OSPF coming into a major site and being blocked into the provider managed MPLS downstream in the network.
So like this
R1-PE-Site-A---MPLS----R2-PE-Site-A <-subnet from major site arrives here
| | & DN bit set
site A core R1-----------site a core R2 <-ospf route propagated to R1
| | & R2 DN bit set
AR1 AR2
| |
Provider 1 MPLS Provider 2 MPLS <-ospf route blocked due to dn bit
| |
smaller remote sites--------smaller remote sites
Log story short what is the best PE-CE peering at the major sites to the ASR company managed MPLS backbone?
Thanks in advance!
