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tech:network:cisco:multicast:routing:pim:ipv6:ipv6-pim:ipv6-pim

IPv6 PIM Introduction

What is IPv6 PIM(PIMv6)?

  1. IPv6 PIM is multicast routing protocol between router.
  2. IPv6 PIM create distribution tree, and routing multicast packet.
  3. IPv6 PIM also called PIMv6.
  4. IPv6 PIM doesn't have Dense Mode.
  5. IPv6 PIM always works with Sparse Mode.
  6. So, IPv6 PIM uses RP(Rendezvous Point) centric distribution tree.
  7. IPv6 PIM behavior is almost same IPv4 PIMv2.
  8. Source Tree
    1. Sender → RP: PIM Register Message
    2. RP → Sender: PIM (S, G) Join Message
  9. Receiver → RP: MLD Membership Report → PIM (*, G) Join Message
  10. IPv6 PIM also has Switchover feature same as PIMv2.
  11. If between LHR(Last Hop Router) and Receiver use MLDv2, Join with Source address specification, can use SSM(Source Specific Multicast) routing by Sender to Receiver shortest path.
  12. RP definition methodology
    1. Static RP
    2. BSR(Boot Strap Router)

Shared Tree

  1. IPv6 PIM Shared Tree creation started when Receiver send MLD Message(Multicast Listener Report) to LHR(Last Hop Router).
  2. When LHR receive MLD Message, create the multicast group (*, G) entry. e.g. (*, FF05::3333)
  3. Next, LHR send PIM (*, G) Join Message to RPF neighbor. e.g. PIM (*, FF05::3333) Join
  4. The router receive the PIM (*, G) Join Message also create (*, G) entry.
  5. Repeat above step until reach RP, IPv6 PIM create Shared Tree.
  6. Shared Tree Example
    1. LHR(R3)
      1. (*, FF05::3333)
        1. Incoming Interface: Gi0/2
        2. Outgoing Interface: Gi0/0
    2. RP(R2)
      1. (*, FF05::3333)
        1. Incoming Interface: Gi0/2
        2. Outgoing Interface: Tunnel
  7. Shared Tree difference to IPv4 PIMv2
    1. PIMv2 RP (*, G) entry
      1. Incoming Interface: Null.
      2. RPF neighbor: 0.0.0.0
    2. IPv6 PIM RP (*, G) entry
      1. Incoming Interface: Tunnel interface for PIM encapsulation
      2. RPF neighbor: IPv6 address of RP itself

Source Tree

  1. IPv6 PIM Source Tree creation started when Sender send multicast packet to FHR(First Hop Router).
  2. When FHR receive multicast packet from Sender, create the multicast group (S, G) entry. e.g. (2001:1:1:3::1, FF05::3333)
  3. FHR initial state
    1. IPv6 PIM
      1. (S, G) entry
        1. Incoming Interface: Interface that received multicast packet.
        2. Outgoing Interface: Tunnel Interface that encapsulate PIM Register Message.
        3. RPF neighbor: Sender IPv6 address
    2. PIMv2
      1. (S, G) entry
        1. Incoming Interface: Interface that received multicast packet.
        2. Outgoing Interface List(OIL): Null
        3. RPF neighbor: 0.0.0.0
  4. FHR(R1) encapsulate received multicast packet with PIM Register Message, and send PIM Register Message to RP by unicast.
  5. When RP(R2) receive PIM Register Message, create (S, G) entry, decapsulate, and routing multicast packet.
  6. Currently, FHR to RP traffic is forwarded by unicast, now create the Source Tree to RP to FHR.
  7. RP send PIM (S, G) Join Message to FHR. e.g. PIM (2001:1:1:3::1, FF05::3333) Join Message
  8. When FHR receive PIM (S, G) Join Message create correspond (S, G) entry, and (S, G) entry Outgoing Interface update to Gi0/2.
  9. Now, ready to multicast routing!
  10. So, RP doesn't require PIM Register Message anymore, RP send PIM Register-stop Message to FHR(R1).
  11. As a result, FHR stop to send PIM Register Message to RP, finally forward multicast packet only.
  12. Source Tree Example
    1. Phase 1: PIM Register Message
      1. FHR(R1)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/0
          2. Outgoing Interface: Tunnel
      2. RP(R2)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/1
          2. Outgoing Interface: Gi0/2
        2. (*, FF05::3333)
          1. Incoming Interface: Tunnel
          2. Outgoing Interface: Gi0/2
    2. Phase 2: PIM (S, G) Join Message
      1. FHR(R1)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/0
          2. Outgoing Interface: Gi0/2
      2. RP(R2)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/1
          2. Outgoing Interface: Gi0/2
        2. (*, FF05::3333)
          1. Incoming Interface: Tunnel
          2. Outgoing Interface: Gi0/2
    3. Phase 3: PIM Register-stop Message(Shared Tree Creation Ommited)
    4. Phase 4: Final State(Shared Tree and Source Tree created)
      1. FHR(R1)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/0
          2. Outgoing Interface: Gi0/2
      2. RP(R2)
        1. (2001:1:1:3::1, FF05::3333)
          1. Incoming Interface: Gi0/1
          2. Outgoing Interface: Gi0/2
        2. (*, FF05::3333)
          1. Incoming Interface: Tunnel
          2. Outgoing Interface: Gi0/2
      3. LHR(R3)
        1. (*, FF05::3333)
          1. Incoming Interface: Gi0/2
          2. Outgoing Interface: Gi0/0

References

tech/network/cisco/multicast/routing/pim/ipv6/ipv6-pim/ipv6-pim.txt · Last modified: 2021/07/23 13:27 by wnoguchi