384
(*,FF1E::101)
Protocol: pim-dm, Flag: WC
UpTime: 00:04:25
Upstream interface: NULL
Upstream neighbor: NULL
RPF prime neighbor: NULL
Downstream interface(s) information:
Total number of downstreams: 1
1: Ethernet1/1
Protocol: igmp, UpTime: 00:04:25, Expires: never
(1001::100, FF1E::101)
Protocol: pim-dm, Flag: ACT
UpTime: 00:06:14
Upstream interface: Tunnel0
Upstream neighbor: 5001::1
RPF prime neighbor: 5001::1
Downstream interface(s) information:
Total number of downstreams: 1
1: Ethernet1/1
Protocol: pim-dm, UpTime: 00:04:25, Expires: never
The output shows that Router A is the RPF neighbor of Router C and the IPv6 multicast data from Router
A is delivered over a GRE tunnel to Router C.
Troubleshooting abnormal termination of IPv6 multicast data
Symptom
•
A host sends an MLD report announcing its joining an IPv6 multicast group (G). However, no
member information about the IPv6 multicast group (G) exists on the intermediate router. The
intermediate router can receive IPv6 multicast packets successfully, but the packets cannot reach the
stub network.
•
The interface of the intermediate router receives the IPv6 multicast packets, but no corresponding (S,
G) entry exists in the IPv6 PIM routing table.
Analysis
•
Before forwarding an IPv6 multicast packet, the router decreases the hop limit value in the IPv6
packet header by 1 and recalculates the checksum. Then, the router forwards the IPv6 multicast
packet to all outgoing interfaces. If the
multicast ipv6 minimum-hoplimit
command is configured on
the outgoing interfaces, the hop limit value in the IPv6 packet header must be no less than the
configured minimum hop limit value. Otherwise, the packet is discarded.
•
The
multicast ipv6 boundary
command filters IPv6 multicast packets received on an interface. If an
IPv6 multicast packet fails to match the IPv6 ACL rule of this command, IPv6 PIM creates no routing
entry.
•
In addition, the
source-policy
command in IPv6 PIM filters received IPv6 multicast packets. If an IPv6
multicast packet fails to match the IPv6 ACL rule of this command, IPv6 PIM does not create a
routing entry.