Version: NE40E&80E V300R002C05B020, V300R002C06B325
When IPTV service goes throught NE40E VPLS it works fine for a sort period of time (4 minuts), after that period of time the image become in a black screen, for IPTV service to continue working it has to be changed the channel and it works for other short period of time (4 minuts).
IPTV Server --------------Router--------------------Router-------------IPTV client.
1): Use an LPUG to directly connect to the IPTV server device, which avoids problems caused by using LPUBs on the upstream and downstream.
2) Intall patch: V300R002C06B325HP0014 to can use LPUB and solve problem.
After re-creating the fault in the lab and analyzing the symptoms, It was find that if the upstream and downstream boards of the Router accessing of VPLS are both LPUBs, the TTL field in the IP header of the reserved multicast packets (the destination IP address is 224.0.0.X) is minus 1 and then is copied into the MPLS label when tunnel encapsulation is conducted.
For IGMP packets, the Query packets sent by routers and Leave packets sent by hosts have the same IP header as that of the reserved multicast packet and the TTL field in the IP header is 1, therefore the TTL field in the encapsulated MPLS label changes to 0 after an IGMP packet is processed on the LPUB.
As TTL field change to 0 this packet is droped and doesn't reach final users.