Carrier Supporting Carrier

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.

For full details on how CsC works check out this document.

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