VXLAN Part IV: The Underlay Network – Multidestination Traffic: PIM BiDir

My Last post, VXLAN Part III, introduces VXLAN Fabric L2VNI service with Anycast-RP PIM (RFC4610 and RFC 7761). In this chapter, I will show how the PIM BiDir (RFC5015) with Phantom-RP can be used for the same purpose. I will use configurations, show commands and Wireshark captures to explain the theory part.

Figure 1: Example VIRL topology

VXLAN Part III: The Underlay Network – Multidestination Traffic: Anycast-RP with PIM

The role of the Underlay Network, related to BUM traffic in the VXLAN fabric, is to transport ARP, ND, DHCP and other Layer 2 BUM (Broadcast, Unknown Unicast, and Multicast) traffic between the hosts connected to different VTEPs. For the Layer 3 Multicast traffic between hosts, there should be an overlay Multicast routing design. This chapter shows how an Anycast-RP with PIM can be used in a VXLAN fabric. In figure 1, we can see our example topology used in this chapter. There are two Spine switches, which shares the same Anycast-RP IP address and belongs to the same “Anycast-RP set” group (Loopback 238). In addition to that, there is an another loopback interface, which must be unique in each Spine (Loopback 511 and 512). These addresses are used as an Anycast-RP group member Id. Both addresses, shared and unique, needs to be reachable for all switches. Complete configuration can be found from the Appendix 1 at the end of the document.

Note! I am using Cisco VIRL with nxos.7.0.3.I7.1

Figure 1: Example topology with Anycast-RP - IP addresses.