iBGP (lrc,lr1,lr2)

Here we should have some explanation in order to understand the whole config.

Please check here for routing topology

LR1 and LR2 configuration is very straightforward, we added them to AS65501 iBGP with bgp group and exported loopback networks via prefix-list and policy-statemen.

LRC is our „hero“ and some important configurations are happen here .. let see them

LRC will be our ibgp route reflector, the simplest config is to adding „cluster cluster_id“ , the rest of the ibgp group configuration is same/similar as LR1 and LR2.

prefix-list ibgp-export: In real world we will want IGP protocol like ospf between ibgp neighbors, however here we do not want to mix ibgp with ospf, with this approach we will keep AS 65501 pure iBGP.

This prefix list will export all connected networks betwen all other logical systems to iBGP LR1 and LR2. Since we do not use IGP we want those network in iBGP in order LR1 and LR2 to know how to find the next-hop for loopback networks which they recevie via iBGP (policy-statement ibgp-export term export-lo) plus LRC loopback network.

With policy-statement ibgp-export and policy-statement ospf-export we exchange routes between ospf and ibgp, so acx1100 will receive LR1 and LR2 loopback networks and vice versa.

Finaly we export filtered direct connect networks from LRC to ospf with policy-statement ospf-export, so acx1100 will know the networks for the next-hop and how to reach LR1 and LR2 loopback networks .. protocol direct is similar to prefix-list export but with direct connected networtk filtering with the help of route-filter

If everything is configured correctly:

  • acx1100 will have all networks from AS65501 and will know how to reach them.
  • LR1 and LR2 will have all networks from AS65501, will know how to reach them, also will know acx1100 networks from ospf between LRC and acx1100
  • All logical systems nodes will have access to internet ! (nat)

LR1

LR2

LRC (iBGP Route Reflector)

Validation

acx1100

LRC

LR1

LR2

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