IPv4 Address Ranges

  • 224/4 = →

  • 224/8 = link local only

  • 232/8 = SSM

  • 233/8 = GLOP


  • Host to default gateway router.

  • IGMP Snooping on LAN switch: reduces LAN traffic.

  • IGMP v3: adds explicit leave.


  • Router to router.

  • PIM-SM:

    • explicitly builds unidirectional shared tree (rooted at the RP).

  • PIM-DM:

    • implicitly builds shortest path trees by flooding multicast traffic domain-wide and then pruning back where not needed (i.e. no receivers).

  • PIM-SSM:

    • build tree rooted at one source.


  • Extension to OSPF that allows routers to share info about group memberships.


  • Extension to BGP.

  • Allows multicast topology info to be exchanged separately from normal unicast info.

  • Still relies on underlying PIM.


  • Allows PIM-SM to have RP redundancy.

  • Allows inter-domain multicast.

  • Each multicast tree has an RP, and all RPs are peers.

Useful Articles

  • Multicast in an EVPN world. [NANOG 72 YouTube]

  • Create IP multicast tree graphs from operational data. [ipSpace]

  • DMVPN or firewall-based VPNs? [ipSpace]

  • Using FQDN for DMVPN hubs. [Fragmentation Needed]

  • Where do you want to move the complexity? [ipSpace]

  • Regional internet exits in large DMVPN deployment. [ipSpace]

  • Inter-VRF NAT in DMVPN deployments. [ipSpace, ipSpace]

  • Label switched multicast - Ethernet header. [Packet Mischief]

  • The future of multicast and QoS. [ipSpace]

  • Label Switched Multicast (LSM) -- an introduction. [Packet Mischief]

  • OSPF vs EIGRP for DMVPN. [Packet Mischief]

  • DMVPN split default routing. [ipSpace]

    • DMVPN split default routing and internet access. [ipSpace]

  • PMTUD doesn't work with IP multicast. [ipSpace]

  • More PIM-BiDir considerations. [Lost In Transit]

  • IPv6 multicast. [Lost In Transit]

  • Next-generation multicast: NG-MVPN. [Lost in Transit]

  • HSRP-aware PIM. [Lost In Transit]

  • Scaling overlay virtual networking videos. [ipSpace]

  • Unreliable multicast means unreliable VMware VSAN. [EtherealMind]

  • Using EEM to speed up multicast convergence when receiver is dually connected. [Lost in Transit]

  • Lessons learned from deploying multicast. [Lost in Transit]

  • How to configure IP multicast PIM on ECMP (on Mellanox). [EtherealMind] [Mellanox]

  • Interdomain multicast. [Reddit]

  • Scaling BGP-based DMVPN networks. [ipSpace]

  • The fundamental difference between phase 2 and phase 3 DMVPN. [ipSpace]

  • Easy to follow resource for multicast. [Reddit]

  • IGMP and PIM in multicast VXLAN transport networks. [ipSpace]

  • BGP routing in DMVPN networks. [ipSpace]

  • IGMP snooping in IPTV. [StackExchange]

  • Combining DMVPN with existing MPLS/VPN network. [ipSpace]

    • Integrating DMVPN-based Internet VPN with MPLS/VPN WAN. [ipSpace]

  • RSVP over DMVPN. [ipSpace]

  • More private AS numbers. [ipSpace]

  • The impact of changed NHRP behaviour in DMVPN networks. [ipSpace]

  • VM-level IP multicast over VXLAN. [ipSpace]

  • NHRP rate limiting can hurt your DMVPN network. [ipSpace]

  • Migrating from a phase 1 DMVPN to a phase 2/3 network. [ipSpace]

  • Redundant DMVPN designs. [ipSpace: part 1, part 2]

  • Multiple DMVPNs on a single hub. [PacketLife]

  • NVGRE -- because one standard just wouldn't be enough. [IOS Hints]

  • OSPF-over-DMVPN using two hub routers. [IOS Hints]

  • DMVPN as a backup for MPLS/VPN. [IOS Hints]

  • Video: Auto-RP over NBMA design issues. [CCIE Blog]

  • More OSPF-over-DMVPN questions. [IOS Hints]

  • Understanding static multicast routes. [CCIE Blog]

  • QoS in large-scale DMVPN networks. [IOS Hints]

  • Spoke-to-spoke IP multicast over DMVPN? [IOS Hints]

  • Understanding advanced PIM shared tree designs. [CCIE Blog]

  • Troubleshooting multicast routing. [CCIE Blog]

  • PIM-SSM. [PacketLife]

  • IP multicast is like Banyan Vines. [IOS Hints]

  • RFC 5790 - lightweight IGMPv3 and MLDv2 protocols - another shot at multicast - but why? [Etherealmind]

  • RFC 5771: IANA guidelines for for IPv4 multicast address assignments. [IETF]

© Robert Larsen. All rights reserved.