Abstract: In general, techniques are described for load-balancing responsibility for forwarding of multicast traffic into an active-active Ethernet segment between two or more multi-homed provider edge (PE) routers in an Ethernet Virtual Private Network (EVPN). In one example, a PE router may receive an Internet Group Management Protocol (IGMP) join report for a multicast group. The PE router may send join synch routes used to synchronize the join report for the multicast group across the Ethernet segment. The PE router may deterministically determine whether the PE router is configured to be an elected multicast forwarder for one of a plurality of multicast groups. If the PE router is elected a multicast forwarder, the PE router may configure a forwarding state of the PE router to ignore a designated forwarder calculation and to forward the multicast traffic into the Ethernet segment regardless of whether the PE router is a designated forwarder.

Abstract: In some examples, a customer edge device (CE) is configured to receive configuration data for multi-homed connectivity for a local layer 2 (L2) network with a L2 virtual private network (L2VPN) for a layer 3 (L3) network for switching L2 packet data units (PDUs) among two or more L2 networks connected to the L3 network including the local L2 network, wherein the configuration data for multi-homed connectivity configures the CE with a primary attachment circuit to a primary neighbor provider edge device (PE) for the L2VPN and with a backup attachment circuit to a backup neighbor PE for the L2VPN; and generate and send, in response to snooping a multicast join message indicating a multicast group, a control plane message via the backup attachment circuit to the backup neighbor PE for the L2VPN, wherein the control plane message is destined for the backup neighbor PE for the L2VPN.

Abstract: Techniques are described for grouping related flows using a flow attribute value indicated by a modified protocol independent multicast (PIM) join request. According to techniques of this disclosure, a network device is configured to receive, from a downstream network device, two or more first PIM join requests indicating two or more multicast groups. In response to determining that each first PIM join request of the two or more first PIM join requests indicates a common first flow attribute value, the network device is configured to select a common path. The network device is further configured to send two or more second PIM join requests indicating the two or more multicast groups to an upstream network device along the selected common path and toward the source. Each second PIM join request of the two or more second PIM join requests includes a common second flow attribute value.

Abstract: In some examples, a method includes receiving, by a first ingress network device for a network, a source tree join route message from an egress network device for the network, specifying a multicast source and a multicast group, and in response to receiving the source tree join route message, determining, by the ingress network device, whether the multicast source is multi-homed to the network via the first ingress network device and a second ingress network device for the network. The method includes, in response to determining that the multicast source is not multi-homed, forwarding traffic for the multicast source on an inclusive provider tunnel without initiating setup of a selective provider tunnel to the egress network device, and in response to determining that the multicast source is multi-homed, initiating setup of a selective provider tunnel to the egress network device and terminating forwarding multicast traffic on the inclusive provider tunnel.

Abstract: In general, techniques are described for load-balancing responsibility for forwarding of multicast traffic into an active-active Ethernet segment between two or more multi-homed provider edge (PE) routers in an Ethernet Virtual Private Network (EVPN). In one example, a PE router may receive an Internet Group Management Protocol (IGMP) join report for a multicast group. The PE router may send join synch routes used to synchronize the join report for the multicast group across the Ethernet segment. The PE router may deterministically determine whether the PE router is configured to be an elected multicast forwarder for one of a plurality of multicast groups. If the PE router is elected a multicast forwarder, the PE router may configure a forwarding state of the PE router to ignore a designated forwarder calculation and to forward the multicast traffic into the Ethernet segment regardless of whether the PE router is a designated forwarder.

Abstract: Techniques are described for multicast flow prioritization in protocol independent multicast (PIM) networks with multicast flow limits. According to the disclosed techniques, once a router has reached its multicast flow limit, the router may preempt an installed lower priority multicast flow with a newly requested higher priority multicast flow. For example, if a maximum number of multicast flows are installed on the router, then, upon receiving a PIM join for a higher priority flow as compared to the installed flows, the router replaces one of the installed lower priority flows with the received higher priority flow. Furthermore, according to the disclosed techniques, priority values for multicast flows are consistent across a PIM domain and each of the routers within the PIM domain is configured to use the priority values to select a higher priority flow over a lower priority flow.

Abstract: Techniques are described for enhancements to multicast Label Distribution Protocol (mLDP) to support multicast only fast re-route (MoFRR) over a remote loop free alternate (RLFA) backup path. An egress router is configured to generate a modified mLDP control message to signal the RLFA backup path in which an address of a RLFA node is included in an LSPRoot field and an address of an ingress router is included in an opaque data field. In addition, the RLFA node of the RLFA backup path is configured to recognize that it is identified in the LSPRoot field of the modified mLDP control message, and, in response, look up the ingress router identified in the opaque data field of the modified mLDP control message. The RLFA node is further configured to send an mLDP control message that includes the address of the ingress router in the LSPRoot field towards the ingress router.

Abstract: An example method includes exchanging targeted hello messages to establish a targeted neighbor connection between a first routing device and a second routing device, wherein one of the routing devices comprises a central routing device, and wherein another one of the routing devices comprises an ingress routing device. The example method further includes processing a source-active register message that specifies a source address and an identifier that are collectively associated with a multicast stream, and wherein the source-active register message further indicates whether the multicast stream is active or withdrawn.

Abstract: In general, the disclosure describes techniques for communicating multicast group leave requests between two or more load-balanced, multi-homed PE routers included in an Ethernet Virtual Private Network (EVPN). The techniques of the disclosure enable the two or more PE routers to synchronize IGMP state and routing information amongst one another to ensure that the one of the multi-homed PE routers elected as the designated forwarder (DF) ceases forwarding the multicast group traffic to the CE router, even if it is not the PE router that receives the IGMP leave request.

Abstract: An example method includes exchanging targeted hello messages to establish a targeted neighbor connection between a first routing device and a second routing device, wherein one of the routing devices comprises a central routing device, and wherein another one of the routing devices comprises an ingress routing device. The example method further includes processing a source-active register message that specifies a source address and an identifier that are collectively associated with a multicast stream, and wherein the source-active register message further indicates whether the multicast stream is active or withdrawn.

Abstract: Techniques are described for enhancements to Protocol Independent Multicast (PIM) to enable a last hop router (LHR) to perform source discovery and directly build or join a source tree. According to the techniques of this disclosure, the LHR builds a communication channel with a rendezvous point (RP) router and requests source information for at least one multicast group for which the LHR has interested receivers. The RP responds to the request by looking into a register database maintained by the RP and sending source information indicating at least one source that is actively providing traffic for the at least one multicast group. Based on the response, the LHR initiates a (S,G) PIM Join message toward the at least one source for the at least one multicast group to directly build or join at least one source tree.

Abstract: Techniques are described for providing robust control plane asserts in a network using Protocol Independent Multicast (PIM) or other routing protocols for controlling delivery of multicast traffic. In one example, a router includes a control unit having a hardware-based processor executing a Protocol Independent Multicast (PIM) protocol. The control unit, when executing the PIM protocol, initiates an election process for selecting, from a plurality of routers, a forwarding router to forward multicast traffic to a shared media computer network. In addition, the control unit determines whether the multicast traffic has been received by the router and outputs, in association with the election process, a PIM assert message that includes an indication as to whether the router has successfully received the multicast traffic.

Abstract: In some examples, a method includes receiving, by a first ingress network device for a network, a source tree join route message from an egress network device for the network, specifying a multicast source and a multicast group, and in response to receiving the source tree join route message, determining, by the ingress network device, whether the multicast source is multi-homed to the network via the first ingress network device and a second ingress network device for the network. The method includes, in response to determining that the multicast source is not multi-homed, forwarding traffic for the multicast source on an inclusive provider tunnel without initiating setup of a selective provider tunnel to the egress network device, and in response to determining that the multicast source is multi-homed, initiating setup of a selective provider tunnel to the egress network device and terminating forwarding multicast traffic on the inclusive provider tunnel.

Abstract: Techniques are described for enhancements to Protocol Independent Multicast (PIM) in an Any Source Multicast (ASM) mode in order to effectively implement Multicast only Fast Re-Route (MoFRR). According to the PIM ASM mode, a router operating as a last hop router connected to a receiver may initiate establishment of both a shared tree and a shortest path tree over which to receive multicast traffic for a given multicast group. According to the disclosed techniques, the router may use the shortest path tree as a primary path on which to receive the multicast traffic, and may use the shared tree as a secondary or backup path for MoFRR in case a failure occurs on the primary path. The techniques enable the router to perform MoFRR for PIM ASM mode without pruning the multicast traffic from the shared tree, and without building additional trees as secondary paths for MoFRR.

Abstract: In one example, a method includes exchanging, by a first routing device and with a second routing device, targeted hello messages using a Protocol Independent Multicast (PIM) protocol to establish a targeted neighbor connection between the first routing device and the second routing device, wherein the first routing device exchanges the targeted hello messages with the second routing device via at least one intermediate routing device, and wherein at least one of the first or second routing device comprises a rendezvous point (RP). The example method further includes processing, by the first routing device using the targeted neighbor connection, a register message that includes multicast stream data elements, wherein each multicast stream data element identifies a source address and a group address that are collectively associated with a respective multicast stream, and wherein each multicast stream data element further indicates whether the respective multicast stream is active or withdrawn.

Abstract: Techniques are described for enhancements to multicast Label Distribution Protocol (mLDP) to support multicast only fast re-route (MoFRR) over a remote loop free alternate (RLFA) backup path. An egress router is configured to generate a modified mLDP control message to signal the RLFA backup path in which an address of a RLFA node is included in an LSPRoot field and an address of an ingress router is included in an opaque data field. In addition, the RLFA node of the RLFA backup path is configured to recognize that it is identified in the LSPRoot field of the modified mLDP control message, and, in response, look up the ingress router identified in the opaque data field of the modified mLDP control message. The RLFA node is further configured to send an mLDP control message that includes the address of the ingress router in the LSPRoot field towards the ingress router.

Abstract: Network devices can use maximally redundant trees (MRTs) for delivering traffic streams across a network, and for transitioning traffic to a new set of MRTs after a topology change, without dropping traffic. The disclosure describes distributed computation of a set of MRTs from one or more ingress devices to one or more egress devices of the network. In one example, network devices in a network compute a set of MRTs, and establish a set of LSPs along the paths of the set of MRTs. After a change to the network topology, convergence sequencing is managed by a central controller, which centrally orchestrates the sequence for moving traffic from being sent on the old MRT paths to being sent on newly computed MRT paths after the controller determines that all new MRT forwarding state has been installed on the network devices.

Abstract: Techniques are described for enhancements to Protocol Independent Multicast (PIM) to enable a last hop router (LHR) to perform source discovery and directly build or join a source tree. According to the techniques of this disclosure, the LHR builds a communication channel with a rendezvous point (RP) router and requests source information for at least one multicast group for which the LHR has interested receivers. The RP responds to the request by looking into a register database maintained by the RP and sending source information indicating at least one source that is actively providing traffic for the at least one multicast group. Based on the response, the LHR initiates a (S,G) PIM Join message toward the at least one source for the at least one multicast group to directly build or join at least one source tree.

Abstract: An example method includes exchanging targeted hello messages to establish a targeted neighbor connection between a first routing device and a second routing device, wherein one of the routing devices comprises a central routing device, and wherein another one of the routing devices comprises an ingress routing device. The example method further includes processing a source-active register message that specifies a source address and an identifier that are collectively associated with a multicast stream, and wherein the source-active register message further indicates whether the multicast stream is active or withdrawn.

Abstract: In one example, a method includes exchanging, by a first routing device and with a second routing device, targeted hello messages using a Protocol Independent Multicast (PIM) protocol to establish a targeted neighbor connection between the first routing device and the second routing device, wherein the first routing device exchanges the targeted hello messages with the second routing device via at least one intermediate routing device, and wherein at least one of the first or second routing device comprises a rendezvous point (RP). The example method further includes processing, by the first routing device using the targeted neighbor connection, a register message that includes multicast stream data elements, wherein each multicast stream data element identifies a source address and a group address that are collectively associated with a respective multicast stream, and wherein each multicast stream data element further indicates whether the respective multicast stream is active or withdrawn.