Connecting a cable modem to the MPLS core network

Regarding to the requirements of existing and prospective customers, the Linkom-PC team worked on Prof of Concept solution which would allow (in case that CMTS device does not support MPLS) to Cable Operator to connect cable modem to the MPLS core network.

Schematic diagram of Proof of Concept solution:

Casa C3200 MPLS proof of concept diagram


(click on picture to enlarge)

Brief explanations of developed solution:

  • for setup of the MPLS core, we have used routers Cisco 2801.
  • For basics (IGP) routing between routers R1-R4 we have used EIGRP protocol. Each router (R1-R4) run MPLS . On routers R1 and R4 we setup the multi protocol BGP.
  • On routers R1 and R4 we have defined some VRF ‘s. We set the traffic from one VRF  route through the MPLS network to the other VRF ‘s
  • Cisco 3560 switch (SW- 1) is connected to the DHCP/TFTP server, then this L3 switch (SW-1) is connected to router R1 where over routing protocol OSPF certain routes are connected to VRF that is defined on R1 router.
  • Cisco 3560 switch ( SW-2 ) in this deveopled solution, works as a L2 switch and we have used it to provide a connection between the Casa C3200 CMTS and router R4 .
  • CASA CMTS C3200 – on this CMTS device we have used protocols OSPF, IS -IS, and RIP. On the device we have defined two bundle interfaces. The first bundle interface (via the OSPF protocol) is attached to Router R4 in a particular VRF. This allows connection for modems, which are linked via a specified bundle interface to provisioning source. The second bundle interface is connected (via IS -IS protocol to the switch (SW- 1)) , which enables modems connections, using this bundle interface, to the provisioning source.
  • RIP protocol has been used on CASA CMTS C3200 to connect this device to our corporate network and then to allow modems to have the output to the internet

This developed solution and design, confirms that is possible to use CMTS platform which don’t have MPLS support and features (such as Casa Systems C3200), in connections with router, which is part of the MPLS core. This solution allow to specific cable modems (for example, cable modems for business subscribers), to be a part of specific VRF, and its traffic can be routed trough the MPLS core, based on specific needs and requirements of a Service Provider. Other cable modems can be registered and work, without any connection to the MPLS core.

This Proof of Concept solution is developed in our own demo lab.

Linkom-PC team

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