Protocol independent multicast sparse mode (pim-sm) support for data center interconnect

Abstract

Techniques are described for utilizing Protocol Independent Multicast Sparse Mode (PIM-SM) to transport BUM (broadcast, unknown unicast, and multicast) traffic in a Virtual Extensible LAN (VXLAN) underlay of a data center, where the BUM traffic is received on active-active, multi-homed Ethernet virtual private network (EVPN) interconnects between multiple physical data centers. For example, the techniques may readily be applied to support usage of PIM-SM where provider edge (PE) routers of the EVPN operate as gateways between the EVPN and the VXLAN spanning the data center interconnect.

1 : A method comprising:
 receiving, by a rendezvous point (RP) for a multicast group and from a first PE router, a first PIM register message for broadcast, unknown unicast, and multicast (BUM) traffic with a multicast flow identified using a combination of a common anycast address and the multicast group;   receiving, by the RP and from a second PE router, a second PIM register message for the BUM traffic with the multicast flow identified using the combination of the common anycast address and the multicast group;   in response to receiving the first PIM register message and the second PIM register message, selecting, by the RP, the first PE router; and   in response to selecting the first PE router:
 outputting, by the RP and to the first PE router, a join message for the common anycast address and the multicast group; 
 forwarding, by the RP, the BUM traffic for the multicast group from the first PE router; and 
 outputting, by the RP and to the second PE router, a register-stop message for the common anycast address and the multicast group. 
   
     
     
         2 : The method of  claim 1 , further comprising:
 establishing an Ethernet virtual private network (EVPN) data center interconnect (DCI) between a first data center running a virtual extensible local area network (VXLAN) and a second data center, wherein the VXLAN of the first data center is active-active multi-homed to two or more PE routers of the EVPN and includes VXLAN tunnels established using protocol independent multicast-sparse mode (PIM-SM), wherein the two or more PE routers comprise the first PE router and the second PE router.   
     
     
         3 : The method of  claim 2 , further comprising receiving, from the two or more PE routers or any one of a plurality of VXLAN tunnel end points (VTEPs), initial join messages to initiate multicast traffic for the multicast group. 
     
     
         4 : The method of  claim 1 , wherein the second PE router is a designated forwarder (DF) and wherein the first PE router is not a DF. 
     
     
         5 : The method of  claim 1 , wherein forwarding the BUM traffic comprises:
 constructing a multicast distribution tree; and   forwarding the BUM traffic into the multicast distribution tree.   
     
     
         6 : The method of  claim 1 , wherein the first PIM register message indicates a unique source address of a sending interface of the first PE router, the method further comprising:
 associating, by the RP, the first PIM register message with the first PE router based on the unique source address of the sending interface of the first PE router.   
     
     
         7 : The method of  claim 1 , wherein selecting the first PE router is in response to determining the first PE router is a closest one of two or more PE routers to the RP for the multicast group, wherein the two or more PE routers comprise the first PE router and the second PE router. 
     
     
         8 : The method of  claim 1 , wherein forwarding the BUM traffic comprises:
 natively receiving, by the RP, the BUM traffic from the first PE router without encapsulation; and   forwarding, by the RP, the natively received BUM traffic.   
     
     
         9 : The method of  claim 1 , wherein the first PIM register message for the BUM traffic encapsulates a packet of the BUM traffic, the method further comprising:
 extracting, by the RP, the packet of the BUM traffic from the first PIM register message; and   forwarding, by the RP, the packet of the BUM traffic.   
     
     
         10 : The method of  claim 1 , wherein the first PIM register message for the BUM traffic comprises a null register message that does not encapsulate a packet of the BUM traffic. 
     
     
         11 : A router comprising:
 a memory; and   one or more processors coupled to the memory, the one or more processors being configured to:
 receive, from a first PE router, a first PIM register message for broadcast, unknown unicast, and multicast (BUM) traffic with a multicast flow identified using a combination of a common anycast address and a multicast group; 
 receive, from a second PE router, a second PIM register message for the BUM traffic with the multicast flow identified using the combination of the common anycast address and the multicast group; 
 in response to receiving the first PIM register message and the second PIM register message, select the first PE router; and 
 in response to selecting the first PE router:
 output, to the first PE router, a join message for the common anycast address and the multicast group; 
 forward the BUM traffic for the multicast group from the first PE router; and 
 output, to the second PE router, a register-stop message for the common anycast address and the multicast group. 
 
   
     
     
         12 : The router of  claim 11 , wherein the one or more processors are configured to:
 establish an Ethernet virtual private network (EVPN) data center interconnect (DCI) between a first data center running a virtual extensible local area network (VXLAN) and a second data center, wherein the VXLAN of the first data center is active-active multi-homed to two or more PE routers of the EVPN and includes VXLAN tunnels established using protocol independent multicast-sparse mode (PIM-SM), wherein the two or more PE routers comprise the first PE router and the second PE router.   
     
     
         13 : The router of  claim 12 , wherein the one or more processors are configured to receive, from the two or more PE routers or any one of a plurality of VXLAN tunnel end points (VTEPs), initial join messages to initiate multicast traffic for the multicast group. 
     
     
         14 : The router of  claim 11 , wherein the second PE router is a designated forwarder (DF) and wherein the first PE router is not a DF. 
     
     
         15 : The router of  claim 11 , wherein, to forward the BUM traffic, the one or more processors are configured to:
 construct a multicast distribution tree; and   forward the BUM traffic into the multicast distribution tree.   
     
     
         16 : The router of  claim 11 , wherein the first PIM register message indicates a unique source address of a sending interface of the first PE router, the one or more processors being configured to:
 associate the first PIM register message with the first PE router based on the unique source address of the sending interface of the first PE router.   
     
     
         17 : The router of  claim 11 , wherein, to select the first PE router, the one or more processors are configured to select the first PE router in response to determining the first PE router is a closest one of two or more PE routers to the RP for the multicast group, wherein the two or more PE routers comprise the first PE router and the second PE router. 
     
     
         18 : The router of  claim 11 , wherein, to forward the BUM traffic, the one or more processors are configured to:
 natively receive the BUM traffic from the first PE router without encapsulation; and   forward, by the RP, the natively received BUM traffic.   
     
     
         19 : The router of  claim 11 , wherein the first PIM register message for the BUM traffic encapsulates a packet of the BUM traffic, the one or more processors being configured to:
 extract the packet of the BUM traffic from the first PIM register message; and   forward the packet of the BUM traffic.   
     
     
         20 : A computer-readable medium comprising instruction that cause a processor of a rendezvous point (RP) for a multicast group to:
 receive, from a first PE router, a first PIM register message for broadcast, unknown unicast, and multicast (BUM) traffic with a multicast flow identified using a combination of a common anycast address and the multicast group;   receive, from a second PE router, a second PIM register message for the BUM traffic with the multicast flow identified using the combination of the common anycast address and the multicast group;   in response to receiving the first PIM register message and the second PIM register message, select the first PE router; and   in response to selecting the first PE router:
 output, to the first PE router, a join message for the common anycast address and the multicast group; 
 forward the BUM traffic for the multicast group from the first PE router; and 
 output, to the second PE router, a register-stop message for the common anycast address and the multicast group.