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Improper Networking Makes It Impossible for the NE40E to Send Source Registration Packets, Thus Causing the IPTV Failure

Publication Date:  2012-07-27 Views:  87 Downloads:  0
Issue Description
1. The networking is shown in the appendix: Three NE40Es and two 7750 routers reside in the same AS that runs IS-IS and PIM-SM. NE40E-2 interconnects with the third-party router, R1, through a GE port. A multicast source server is attached to R1, which pushes the multicast source directly to NE40E-2 through PIM-DM. The static RP is set to the address of loopback1 of 7750-2.
2. Users cannot watch any program on any channel. 
Alarm Information
Handling Process
1. Check the port of NE40E-2 connecting to R1. It is found that the port receives nearly 400 Mbit/s multicast traffic.
2. Check the (S, G) entries of NE40E-2. The entries of all channels are found existing.
3. Check the (S, G) entries of 7750-2. No entries are found existing.
4. Check the routing table of 7750-2. The inbound port is believed to work normally.
5. Trace source registration packets by running the debugging command on 7750-2. No source registration packets are traced.
6. Set the static RP to the address of loopback1 of NE40E-2. In this case, users can watch programs of all channels. 
Root Cause
1. The Rendezvous Point Tree (RPT) is not established.
2. The source tree is not established.
3. The program source fails to reach NE40E-2.
4. The RPF check fails. 
1. After R1 directs multicast traffic to NE40E-2 through PIM-DM, NE40E-2 establishes (S, G) entries. Because NE40E-2 is not the SDR, it does not send source registration packets to RP.
2. R1, as the SDR, is configured with PIM-DM. Unlike SM, R1 does not register (S, G) entries with RP through the register mechanism. Therefore, RP cannot direct the traffic to the receiver.
3. When receiving multicast traffic, NE40E-2 checks the source IP addresses. Because the source IP addresses do not fall within the directly connected network segment, NE40E-2 does not take itself as the SDR.
4. When configured with RP, NE40E-2 directs multicast traffic through the PIM-SM RPT or SPT after receiving (*, G) entries from the receiver.