BGP, Full Mesh and Route Reflector setup

Hello Experts,

We are small wisp, and have an ospf network, as attached, and now we want to do full mesh bgp and route reflection, i ahve tried to read on internet but cannot understand how full mesh is implemented and works, on the map R1 and R2 are main routers, and R3 to R9, are routers but have clients connected to them, part of our main ospf network. This is just an example but we have like 30 routers, with clients on them and connected by various links, wireless and fiber so multiple link to each router.

If i do full mesh bgp, how do i link all these up ?

Any pointers ?

Many thanks for the time.
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Jan SpringerCommented:
That's a lot of overhead.

Typically, I configure eBGP on each router to its external peer and all routers with eBGP peering sessions have an iBGP session between each other.

Everything else is OSPF.

You have 9 eBGP peering sessions?
skywalker7Author Commented:
At the moment all is osfp, I just want to start to configure ibgp on these routers as full mesh, but have no idea on which routers to configure and how to peer to each other.

Jan SpringerCommented:
You configure BGP with our upstream providers.

You configure BGP between all of your routers that have eBGP peers.

Send default routes downstream to all other routers.
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

skywalker7Author Commented:
Thank you for the response, at the moment I am not doing bgp with upstream, and i only want to do full bgp mesh where later i can do route reflect, after that i can do bgp with my clients who are connected to me with more then one link.

But am stuck on how to do full mesh bgp, how do i go about it, like R3 - R4, and R4-R5 and R5 - R6 or how do i go about it.

Full-mesh would require that each router is configured as a neighbor to every other router.  So, in your diagram, on R1, you'll configure a neighbor to R2, R3, R4, ... , R9.  Same then for R2 (neighbors to R1, R3, ... , R9), and so on.  This can become tiresome on 30 routers, which is where route-reflectors start to become handy.

Remember that BGP runs on TCP sessions between BGP speakers, so a) neighbors does not need to be directly connected, and b) you will still need an IGP for internal reachability.
skywalker7Author Commented:
Thank you for the response.

To make it simple, can i make R1 and R2 to be route reflectors and R3 to R7 to peer with R1 and R2 ? Would that work ? and do i do iBGP ? and if a client connects to R5 and R9, how can i do BGP with client, Ibgp or eBGP ?  thanks.

I have ospf for internal reachability.
Yes, you can make R1 and R2 route reflectors, but why don't you want to add R8 and R9 as route-reflector clients?  If you do not add R8 & R9 as route reflector clients, you have to set-up a full mesh between R1, R2, R8 and R9.

You can also have multiple RR clusters: For example use R1 as RR for R3 & R4, R7 as RR for R9, and R2/R6 as RRs for R1, R5, R7 & R8.  This can get tricky, though - A router can only be RR for a single cluster, but can be a RR client in another cluster.  Also, if a RR is not a client in another cluster, it must be fully meshed to other BGP speakers that is not RR clients.  Best practice would indicate that you set down clear design rules for which routers are/can be route reflectors, if multiple route-reflector clusters will be allowed, and design rules regarding these.  The simpler these rules, the less chance there will be of mistakes creeping in.

Route-reflectors are specific for iBGP (devices within the same AS), and I assumed R1 - R9 will run on the same BGP AS number.  If a client connects to you, best practice dictates eBGP (to connect a client via iBGP will require inclusion in your OSPF process, and being configured either as a route-reflector client, or full mesh to RR's and other non-clients - not reccommended!)

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
skywalker7Author Commented:
Thank you for the detailed explanation, this will help me plan my network. I am going set a design on paper and then implement it.

Thanks again.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.