The network layout is simple (details in Drawing1 file attached):
Stream server--access-->([eth2/0/2, vlan902] NE40 [gig1/0/2,vlan902])---trunk-->backbone node.
Multicast traffic initiated at the stream server enters NE40 through Fast Ethernet port 2/0/2 in 902 vlan. Then the multicast stream is expected to go out the Gigabit Ethernet 1/0/2 port towards backbone node for spreading within another AS. Both interface Ethernet 2/0/2 and Gigabit-Ethernet 1/0/2 are configured with vlan 902 so the task for NE40 is just to transmit multicast from one port to another at level 2 without any analyzing and modification. None of any igmp or multicast data is configured. But in this circumstances the appearance was as follows:
Traffic statistic at Ethernet 2/0/2:
Last 5 minutes input rate 7917837 bytes/sec, 5814 packets/sec
Last 5 minutes output rate 7 bytes/sec, 0 packets/sec
Traffic statistic at Gigabit-Ethernet 1/0/2:
Last 5 minutes input rate 72 bytes/sec, 0 packets/sec
Last 5 minutes output rate 1340389 bytes/sec, 983 packets/sec
One can see that the rate of outgoing multicast traffic amounts only about 17% of the incoming traffic rate. So considerable part of the multicast is lost.
1. it was cleared up that NE40 router treats unknown multicast traffic the same way as as it do a broadcast one. Meanwhile broadcast traffic can occupy only 10% of the total bandwidth of any port by default. Command broadcast-suppression is used to change the permitted rate for broadcast traffic at the port.
2. So after setting broadcast suppression ratio as 90% for Ethernet 2/0/2 (ingress port for multicasting traffic) the problem has been solved. Amount of incoming multicast has became equal to that of outgoing multicast.
1. Part of multicast trafic is discarded so it's reasonably to suppose that some kind of traffic suppression is configured
2. Trying to find traffic suppression configuration commands for multicast - no any appropriate configuration is performed at NE40.
Please, be aware that NE40 router treats unknown multicast traffic as broadcast traffic! And if you don’t use any multicast routing and apply transparent transmission of multicast flows through NE40 be informed about need to expand permitted bandwidth if necessary because in such networking any multicast traffic will be treated by NE40 as unknown multicast and consequently rules for broadcast suppression will be applied to it.