This lab showcases a Carrier Supporting Carrier setup. It shows a Customer with two sites connected to ISP1 who in turn, has two disparate areas connected via a Backbone Provider implementing CsC. Customer A has two sites connected to ISP1 in a VRF called CUST_1.
The following are the primary features of this CsC design:
IS-IS and LDP is used throughout ISP1.
ISP1 has one route reflector in each area running VPNv4 to the PE routers, and between each other.
The connection between ASBR1 and BB-PE1 is running OSPF and LDP.
The loopbacks of RR1 and PE1 are redistributed from IS-IS into OSPF and sent to BB-PE1.
ASBR1 also redistributes from OSPF into IS-IS (this is expected to be loopbacks for RR2 and PE2).
The connection between ASBR2 and BB-PE2 is running BGP-LU.
The loopbacks for RR2 and PE2 are advertised to BB-PE2.
Instead of redistributing into the local IGP, ASRB1 runs BGP-LU to RR2 who in turn runs BGP-LU to PE2 into order to communicate the label for PE1.
The customer subnets are represented by loopbacks on the CE routers.